Lately, I have been mostly occupied with a=20 seismometers for schools project. One of the sensor types that I have tried=20 uses piezo electric disks. They have a high voltage sensitivity.

The disks also seem to be quite good at detecti= ng=20 low frequency sound / air pressure changes; low flying helicopters in=20 particular! I have a twin flask arrangement which I have been doing som= e=20 initial experiments with. One flask acts as a stable air pressure reservoir=20= and=20 the other as a low pass acoustic filter. I prefer to remove ambient noise as= far=20 as possible, rather than detecting it and then filtering the signal. This al= so=20 stabilises the temperature of the detector disk reasonably well. Reducing=20 ambient wind and other noises is reported to be a major=20 consideration.

    One of the older types of infrasound array used= a=20 large circular pipe connected to a sensor at the centre by several hard radi= al=20 pipes, typically six to eight. You should be able to use porous hose fo= r=20 the circle and maybe PVC hose / water pipe for the radial arms? This might g= ive=20 better noise cancellation and a higher sensitivity than two folded pipes? A=20 circle of 25 ft radius has a perimeter of about 157 ft. This could give= you=20 a collection area of nearly 2,000 sq ft. Air pressure eddies less than this=20= size=20 will tend to cancel out. You might get a hf noise cut-off at about 20 H= z. I=20 note that some of the current CTBT arrays are using solid pipe at the centre= of=20 the spokes and porous pipe for remainder. Porous hose is reported to change=20= it's=20 acoustic characteristics with time and it is also sensitive to rain.

    Is your 1 Hz figure a high frequency cut-off? I= =20 have got some characteristics of Validyne sensors somewhere. The low range=20 sensors are from 0.1" water FS upwards, but I don't remember=20= any=20 frequency or noise specifications. I don't know how much they cost, but a Ba= ll=20 Glider Variometer might well offer both price and sensitivity advantages. Th= ey=20 use the same principle of pressure sensor, but with a mylar membrane. You ca= n=20 also get low pressure range silicon sensors.

    Regards,

    Chris Chapman
Subject: INFRASOUND From: AHrubetz@....... Date: Wed, 4 Jan 2006 23:24:59 EST Hi Chris, Thanks very much for the interesting information pertaining to the various detectors and Infrasound detector arrays. Unfortunately, I am restricted to a rather narrow outside rectangular area ( about 2' x 25') for my detector and porous hose layout, hence the linearity of the configuration. Yes, it would be ideal to use radial arms and/or a circular configuration to supress ambient noise but I have to work with this restriction, at least for now. I was advised to use a 1 Hz HP filter, and recorded in this mode for about a month before removing the filter. I believe it eliminated too much of the lower frequencies that enriched the Infrasound signal. I have had some good correlation with weather fronts and barograph changes. I also recorded what appeared to be Infrasound correlation with solar radiation storms several months ago, but have not had the time to make further attempts at this or other correlative studies. I will keep you advised if I come up with anything interesting, solar or terrestial! Best regards, Al
Hi Chris,

    Thanks very much for the interesting informa= tion pertaining to the various detectors and Infrasound detector arrays.&nbs= p; Unfortunately, I am restricted to a rather narrow outside rectangular&nbs= p;area ( about 2' x 25') for my detector and porous hose layout, hence=20= the linearity of the configuration. Yes, it would be ideal to use radi= al arms and/or a circular configuration to supress ambient noise but I have=20= to work with this restriction, at least for now. I was advised to use=20= a 1 Hz HP filter, and recorded in this mode for about a month before removin= g the filter. I believe it eliminated too much of the lower frequencie= s that enriched the Infrasound signal.

     I have had some good correla= tion with weather fronts and barograph changes.  I also recorded w= hat appeared to be Infrasound correlation with solar radiation storms s= everal months ago, but have not had the time to make further attem= pts at this or other correlative studies. I will keep you advised if I= come up with anything interesting, solar or terrestial!

    Best regards,

    Al
Subject: Range of 4,5Hz geophone From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 07 Jan 2006 12:37:59 +0000 Hi all What is the estimated range of 4,5Hz Geophone to detect earthquakes, three axis ? Then i am counting in kilometers. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone From: ian ian@........... Date: Sat, 07 Jan 2006 13:54:23 +0000 if it's any help, I picked up the 3.0 mag quake at Fort William, Scotland on the 10th of December. I'm probably about 150 Km away, see http://www.earthquakes.bgs.ac.uk/recent_events/20051210232129.9.html (I'm just to the right of Edinburgh, having fallen off the map!). I have a single, vertical 4.5 Hz geophone and got a very respectable trace from it. I would agree, though, that life is more "exciting" with a long period device, like a Lehman, unless you live "on top of a volcano", as I used to do. Cheers Ian http://www.iasmith.com/realtime.htm J�n Fr�mann wrote: >Hi all > >What is the estimated range of 4,5Hz Geophone to detect earthquakes, >three axis ? Then i am counting in kilometers. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone From: ian ian@........... Date: Sat, 07 Jan 2006 13:54:23 +0000 if it's any help, I picked up the 3.0 mag quake at Fort William, Scotland on the 10th of December. I'm probably about 150 Km away, see http://www.earthquakes.bgs.ac.uk/recent_events/20051210232129.9.html (I'm just to the right of Edinburgh, having fallen off the map!). I have a single, vertical 4.5 Hz geophone and got a very respectable trace from it. I would agree, though, that life is more "exciting" with a long period device, like a Lehman, unless you live "on top of a volcano", as I used to do. Cheers Ian http://www.iasmith.com/realtime.htm J�n Fr�mann wrote: >Hi all > >What is the estimated range of 4,5Hz Geophone to detect earthquakes, >three axis ? Then i am counting in kilometers. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 07 Jan 2006 14:11:29 +0000 Hi Ian and others. I did ask becose i didn't pickup a 3,5 mag earthquake that did happen yesterday about 100 - 180 Km nne of where i life. You can get more info on that earthquake here > http://hraun.vedur.is/ja/englishweb/eqlist.html the automatic system that i.m.o has marks it as a 3,8Ml in size, the quality was rather poor on the i.m.o system. But for some reasion i didn't pick it up, i might have setup the warning system in winsdr too hig or something in the ground did prevent me from picking it up, but i did change the setting after i did notice this. To prevent me from recording noise, i did set the sla/tla ratio to 8.0, but far as i understand it. That controls the warning levels pickups. The earthquake that where happening yesterday where on the 2 - 4Hz (problay higher) bands, as can be seen here > http://hraun.vedur.is/ja/oroi/hrn.gif there are more stations http://hraun.vedur.is/ja/englishweb/tremor.html here. The noise level in my evroment is not too hig, based on what i have seen the three weeks i have been running the geophone. But i am still learning proplery on this hardware. That is why i will ask questions. However, yesterday was rather windy day and the noise levels where above the usual level. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auction From: Bob Barns royb1@........... Date: Sat, 07 Jan 2006 09:58:11 -0500 Hi gang, Vintage Seismograph Seiscor Telephone Test Set - L@@k! Item number: 6595047948 ends 1/13 Can someone post what this thing is? It looks capable of almost anything?? Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone From: ian ian@........... Date: Sat, 07 Jan 2006 15:21:39 +0000 Hi, it can also depend on the depth and other factors, whether you pick it up or not. I record my data continuously. Disk space is cheap. I only learned of the Fort William quake about a week after it happened. I went back to the files (I record 30 minutes per file) for the time and date and there it was. Cheers Ian J�n Fr�mann wrote: >Hi Ian and others. > >I did ask becose i didn't pickup a 3,5 mag earthquake that did happen >yesterday about 100 - 180 Km nne of where i life. You can get more info >on that earthquake here > >http://hraun.vedur.is/ja/englishweb/eqlist.html the automatic system >that i.m.o has marks it as a 3,8Ml in size, the quality was rather poor >on the i.m.o system. But for some reasion i didn't pick it up, i might >have setup the warning system in winsdr too hig or something in the >ground did prevent me from picking it up, but i did change the setting >after i did notice this. To prevent me from recording noise, i did set >the sla/tla ratio to 8.0, but far as i understand it. That controls the >warning levels pickups. > >The earthquake that where happening yesterday where on the 2 - 4Hz >(problay higher) bands, as can be seen here > >http://hraun.vedur.is/ja/oroi/hrn.gif there are more stations >http://hraun.vedur.is/ja/englishweb/tremor.html here. > >The noise level in my evroment is not too hig, based on what i have seen >the three weeks i have been running the geophone. But i am still >learning proplery on this hardware. That is why i will ask questions. >However, yesterday was rather windy day and the noise levels where above >the usual level. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Range of 4,5Hz geophone From: "Steve Hammond" shammon1@............. Date: Sat, 7 Jan 2006 09:59:50 -0800 Jon, My station ID is ATx and I have a lot of geophone data on Larry's system under ATE, ATN and ATX that is from three HS-10 geophones with a gain of 2,100. As a rule, I don't look for event data if the event is less than a 3.0 and more than 200 km away, 4.0 and more than 300 km, 5.0 and more than 400 km. Smaller local events less than 2.0 can be lost in the local noise because I live near the Monterey Bay in Central California. Regards, Steve Hammond PSN San Jose, Aptos, California -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of J�n Fr�mann Sent: Saturday, January 07, 2006 4:38 AM To: PSN-Postlist Subject: Range of 4,5Hz geophone Hi all What is the estimated range of 4,5Hz Geophone to detect earthquakes, three axis ? Then i am counting in kilometers. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Range of 4,5Hz geophone From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 07 Jan 2006 21:02:20 +0000 Hi all I do think i found the source of the problem, i think that the ampling of the psnamp board was too low. I did change it, but i am not sure how much i did change it, it has the jumper on and the gain is from 175 - 1750. I did turn them clockwise and i think the settings now at maximum settings. I see bit more noise then i did before. If the range of a 4,5Hz geophone is up to 640 km max, then i problay will not have problems picking up most small quakes that happen near me, or at least up to 200km away from me. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone From: ian ian@........... Date: Sun, 08 Jan 2006 12:40:07 +0000 I'm getting an amazing trace on my Lehman of the Greek quake, still in progress. Interestingly, there is a small event on my geophone which seems to co-incide with the P wave. Is this likely? See http://www.iasmith.com/realtime.htm I'm just about to fit a permanent set of heaters in the box. The temporary desk lamp has been great since I put it in, cured the problem completely. I'll have to wait a bit now so as to not disturb the trace in progress.... Ian Smith J�n Fr�mann wrote: >Hi all > >I do think i found the source of the problem, i think that the ampling >of the psnamp board was too low. I did change it, but i am not sure how >much i did change it, it has the jumper on and the gain is from 175 - >1750. I did turn them clockwise and i think the settings now at maximum >settings. I see bit more noise then i did before. > >If the range of a 4,5Hz geophone is up to 640 km max, then i problay >will not have problems picking up most small quakes that happen near me, >or at least up to 200km away from me. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 08 Jan 2006 16:27:11 +0000 Hi Ian and others. I didn't recored or see this earthquake on my geophone, something probaly shatters the wave before it reaches me or trims it down below the local noise. I know it was detected by the i.m.o siesmonitors. I have alot bigger amplitude on my geophone then before, so i hope to pickup earthquakes when they happen. I now record alot of noise, for instance i see alot more wind being picked up by my geophone, even if it is inside and well isolated. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone From: John or Jan Lahr JohnJan@........ Date: Sun, 08 Jan 2006 08:32:57 -0800 Hi Ian, It's possible that the small event was triggered by the arriving seismic waves, although this usually occurs later when the surface waves are arriving. See, for example, this page by USGS seismologist Andy Michael: http://quake.wr.usgs.gov/~michael/surprises.html This has been observed in may volcanic and hydrothermal areas, where presumable there are some "spots" that are so close to failure that the added strain produced by the waves of a distant earthquake can set some of them off. Andy's main page is: http://quake.wr.usgs.gov/~michael/ This "event" is more likely just the high frequency component of the P wave. It's hard to tell from the seismograms, but if it starts at exactly the same time as P on the Lehman, then it's probably not a triggered event. Cheers, John At 04:40 AM 1/8/2006, you wrote: >I'm getting an amazing trace on my Lehman of the Greek quake, still >in progress. Interestingly, there is a small event on my geophone >which seems to co-incide with the P wave. Is this likely? See >http://www.iasmith.com/realtime.htm > >I'm just about to fit a permanent set of heaters in the box. The >temporary desk lamp has been great since I put it in, cured the >problem completely. I'll have to wait a bit now so as to not >disturb the trace in progress.... > >Ian Smith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone From: ian ian@........... Date: Sun, 08 Jan 2006 16:39:27 +0000 Hi, I wouldn't really expect to pick up a quake from Greece with a geophone at the distance you are at. You really have to have a longer period device to detect it. I'm not sure if the spike on my geophone was the P wave or just something local. Either way, the geophone spike was brief compared to the 90 minutes or so that the quake grumbled on for. Maybe you should have a go at making something like a Lehman. They're not too difficult and you probably have a spare channel on your amp and A/D. I've spent the afternoon replacing the desk lamp in the enclosure with 3 car lights. I'm starting off by feeding them 5 volts from an old PC power supply. If that isn't warm enough then I'll switch to 12 volts. Thanks to Chris Chapman for pointing this out, it's made a huge difference. Cheers Ian J�n Fr�mann wrote: >Hi Ian and others. > >I didn't recored or see this earthquake on my geophone, something >probaly shatters the wave before it reaches me or trims it down below >the local noise. I know it was detected by the i.m.o siesmonitors. I >have alot bigger amplitude on my geophone then before, so i hope to >pickup earthquakes when they happen. I now record alot of noise, for >instance i see alot more wind being picked up by my geophone, even if it >is inside and well isolated. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: The earthquake in Greece From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 08 Jan 2006 16:45:46 +0000 Hi all John, thanks for mension this. Becose there has been a increase in earthquakes in Silicy, Italy after the Greece earthquake. It did start about three hours after the main quake in Greece. You can get the earthquake data here. http://www.emsc-csem.org/cgi-bin/QDM_all.sh?1 Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone From: ian ian@........... Date: Sun, 08 Jan 2006 16:48:07 +0000 Hi, thanks for the links. Interesting thought. If the BGS was working I'd be able to check if it was real or local. BGS sensors have been off since the 24th of December, outrageous and embarrassing. Presumably Monday may bring some hope. I'm tempted to email a complaint to them (it's my taxes!). Thanks Ian John or Jan Lahr wrote: > Hi Ian, > > It's possible that the small event was triggered by the arriving > seismic waves, although this usually occurs later when the surface > waves are arriving. See, for example, this page by USGS seismologist > Andy Michael: > http://quake.wr.usgs.gov/~michael/surprises.html > This has been observed in may volcanic and hydrothermal areas, where > presumable there are some "spots" that are so close to failure that > the added strain produced by the waves of a distant earthquake can set > some of them off. > > Andy's main page is: > http://quake.wr.usgs.gov/~michael/ > > This "event" is more likely just the high frequency component of the P > wave. It's hard to tell from the seismograms, but if it starts at > exactly the same time as P on the Lehman, then it's probably not a > triggered event. > > Cheers, > John > > > At 04:40 AM 1/8/2006, you wrote: > >> I'm getting an amazing trace on my Lehman of the Greek quake, still >> in progress. Interestingly, there is a small event on my geophone >> which seems to co-incide with the P wave. Is this likely? See >> http://www.iasmith.com/realtime.htm >> >> I'm just about to fit a permanent set of heaters in the box. The >> temporary desk lamp has been great since I put it in, cured the >> problem completely. I'll have to wait a bit now so as to not disturb >> the trace in progress.... >> >> Ian Smith > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone,Greek quake From: "Thomas Dick" dickthomas01@............. Date: Sun, 8 Jan 2006 11:13:28 -0600 My vertical geophone detected this quake. I am 82 degrees away. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Range of 4,5Hz geophone From: ChrisAtUpw@....... Date: Sun, 8 Jan 2006 13:29:59 EST In a message dated 08/01/2006, ian@........... writes: I've spent the afternoon replacing the desk lamp in the enclosure with 3 car lights. I'm starting off by feeding them 5 volts from an old PC power supply. If that isn't warm enough then I'll switch to 12 volts. Hi Ian, There are two problems with using light bulbs. You need to run them at 3/4 the rated voltage to get a very long life from them and the glass envelopes need to be kept cool. If the glass gets too hot, oxygen may diffuse through it and shorten the filament life. The other problem is that insects, spiders and small animals are attracted to a warmed environment, particularly if it is also illuminated. Power resistors with an Al case which can be bolted onto an earthed Al top plate in the enclosure and provided with soldered connections are likely to give the most satisfactory permanent solution. Farnell and RS sell them. Regards, Chris Chapman

In a message dated 08/01/2006, ian@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I've=20 spent the afternoon replacing the desk lamp in the enclosure with 3
ca= r=20 lights. I'm starting off by feeding them 5 volts from an old PC
p= ower=20 supply. If that isn't warm enough then I'll switch to 12 volts. =20

Hi Ian,

    There are two problems with using light bulbs.=20= You=20 need to run them at 3/4 the rated voltage to get a very long life from them=20= and=20 the glass envelopes need to be kept cool. If the glass gets too hot, oxygen=20= may=20 diffuse through it and shorten the filament life. The other problem is that=20 insects, spiders and small animals are attracted to a warmed=20 environment, particularly if it is also=20 illuminated.

    Power resistors with an Al case which can be bo= lted=20 onto an earthed Al top plate in the enclosure and provided with soldered=20 connections are likely to give the most satisfactory permanent solution= ..=20 Farnell and RS sell them.

    Regards,

    Chris Chapman
Subject: Re: Range of 4,5Hz geophone From: ian ian@........... Date: Sun, 08 Jan 2006 18:58:50 +0000 Hi, thanks for the warnings. As always, I've taken a short cut (lack of time). I also had to get the desk lamp out by today as my family return tomorrow and will want the desk lamp back(!) and wouldn't want a mains lead stretching across the garden/back yard. It was nice and cosy inside the box when I opened it up, so the thermal insulation isn't too bad. It was around 0C outside at the time. I ripped out the flasher, stop and tail light string from our old Honda and attached that to the inside ceiling of the enclosure. I'm only sending 5 volts dc to them (down 30m of mains lead) so they don't get very hot at all, just a warming glow. Unfortunately I won't have much more time until the summer. So I'll have to wait until then before changing over to resistors. Unless of course it starts going bump in the night! Cheers Ian ChrisAtUpw@....... wrote: > In a message dated 08/01/2006, ian@........... writes: > > I've spent the afternoon replacing the desk lamp in the enclosure > with 3 > car lights. I'm starting off by feeding them 5 volts from an old PC > power supply. If that isn't warm enough then I'll switch to 12 > volts. > > Hi Ian, > > There are two problems with using light bulbs. You need to run > them at 3/4 the rated voltage to get a very long life from them and > the glass envelopes need to be kept cool. If the glass gets too hot, > oxygen may diffuse through it and shorten the filament life. The other > problem is that insects, spiders and small animals are attracted to a > warmed environment, particularly if it is also illuminated. > Power resistors with an Al case which can be bolted onto an > earthed Al top plate in the enclosure and provided with soldered > connections are likely to give the most satisfactory permanent > solution. Farnell and RS sell them. > > Regards, > > Chris Chapman Hi,

thanks for the warnings. As always, I've taken a short cut (lack of time). I also had to get the desk lamp out by today as my family return tomorrow and will want the desk lamp back(!) and wouldn't want a mains lead stretching across the garden/back yard. It was nice and cosy inside the box when I opened it up, so the thermal insulation isn't too bad. It was around 0C outside at the time.

I ripped out the flasher, stop and tail light string from our old Honda and attached that to the inside ceiling of the enclosure. I'm only sending 5 volts dc to them (down 30m of mains lead) so they don't get very hot at all, just a warming glow. Unfortunately I won't have much more time until the summer. So I'll have to wait until then before changing over to resistors. Unless of course it starts going bump in the night!

Cheers

Ian

ChrisAtUpw@....... wrote:

In a message dated 08/01/2006, ian@........... writes:

I've spent the afternoon replacing the desk lamp in the enclosure with 3
car lights. I'm starting off by feeding them 5 volts from an old PC
power supply. If that isn't warm enough then I'll switch to 12 volts.

Hi Ian,

    There are two problems with using light bulbs. You need to run them at 3/4 the rated voltage to get a very long life from them and the glass envelopes need to be kept cool. If the glass gets too hot, oxygen may diffuse through it and shorten the filament life. The other problem is that insects, spiders and small animals are attracted to a warmed environment, particularly if it is also illuminated.

    Power resistors with an Al case which can be bolted onto an earthed Al top plate in the enclosure and provided with soldered connections are likely to give the most satisfactory permanent solution. Farnell and RS sell them.

    Regards,

    Chris Chapman

Subject: Re: Range of 4,5Hz geophone From: "Geoff" gmvoeth@........... Date: Sun, 8 Jan 2006 13:05:42 -0700 I understand the physics of wave propagation through water or ground or anything allows for shadow areas where there is little or no energy. It seems reasonable to assume such shadow areas can affect small areas closer to the event and not just 103 or so degrees away. maybe you were just in one of these shadow zones ??? > I didn't recored or see this earthquake on my geophone, something > probaly shatters the wave before it reaches me or trims it down below > the local noise. I know it was detected by the i.m.o siesmonitors. I But then I am no geophysicist, the person most likely to know. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Online seismonitor graphs are offline From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 09 Jan 2006 01:11:38 +0000 Hi all. My online seismonitors graphs are currently offline due to technical problems. I hope to have them back online tomorrow, but i will have to move them to my own server at my home, so the address will change. I will setup a forward page also on the old place tomorrow (where my page is), so you will get redireced to the new location automaticlly. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Updated link From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 09 Jan 2006 13:08:21 +0000 Hi all I finally got my seismographs online agen (hopefully). There has been minor updated in the link. The current link is http://www.simnet.is/jonfr500/earthquake/ and that this is a backup link number two, the main backup link is this one http://earthquake.homeip.net/~jonfr/ , the main link is going to be http://www.jonfr.com/earthquake/ But at current time i am having problems peforming a update to that location. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Earthquake in the North Atlantic Ocen, 5,3mb From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 09 Jan 2006 17:11:53 +0000 Hi all Today (9th Jan, 2006) there was a earthquake of 5.3 mb in the North Atlantic Ocen, the depth was 2 km. There are more info at esmc-cmes.org and here http://www.emsc-csem.org/cgi-bin/QDM_link_content.sh?HB644&CSEM The link might stop working anytime. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: $200 microbarograph first light From: "David Saum" DSaum@............ Date: Mon, 9 Jan 2006 15:08:10 -0500 I finally got my $200 home-brew microbarograph running yesterday, and here are some pictures: Here is last night's data logged and plotted hourly with the seismic freeware AMASEIS. Time is GMT. Bandpass 0.01 Hz to 4.5 Hz. http://www.infiltec.com/Infrasound@................. The microbarograph was in a cooler, outside on the 4th floor deck of my condo, with no spatial wind averaging array. I am about 10 miles from Washington Reagan airport, and they reported 9-15mph winds, so the peaks are probably wind and not seismic events, nuclear tests, meteors, etc. :( Here is some fine structure of one of last night's events: http://www.infiltec.com/Infrasound@................. The adc pressure resolution is about 0.004 Pa, so a 200 adc count peak is about 0.8 Pa. AMASEIS allows you to block any time segment and examine it in detail, including fourier transform and bandpass filtering. Exterior of microbarograph with serial cable: http://www.infiltec.com/Infrasound@................. Interior of microbarograph: http://www.infiltec.com/Infrasound@................. PCB removed from box http://www.infiltec.com/Infrasound@................. PCB and high-pass pneumatic filter removed from box: http://www.infiltec.com/Infrasound@................. System specs: System Bandpass: 0.01 to 4 Hz. High-Pass filter: ~100 sec or 0.01 Hz using volume/capillary tube. Low pass filter: 4 Hz anti-alias, 8 pole Bessel filter (MAX4701) Differential pressure sensor: silicon, bridge type, 1"wc (DUXL01D) Pres Resolution: ~0.004 Pa - possibly lower depending offsets Range: +/- 120 Pa (32768 times pressure resolution) Amp: instrumentation,1000x,single supply,micropower,RTR out(INA122P) Power: ~2ma 5VDC, derived from PC serial port, no exernal power supply Regulator: 5VDC, low dropout micropower, precision (LP2950-5.0) Amplifer Reference Voltage: 2.5VDC fixed, precision reference (LT1004-2.5) Microprocessor: 4mhz, onboard 16 bit ADC and serial I/O (PIC14000) Firmware: ADC sampling at ~35 SPS, zero drift tracking ~5 min TC. Enclosure: diecast aluminum box for shielding (Hammond 1590P) Serial Out: RS232, 9600 baud, 8N1, ascii records, -32767 to +32767 Wind Spatial Averaging: array of micro-perforated garden tubing Data Log/Display: freeware PC AMASEIS seismic log/analysis software Improvements?: Offset voltages in the instrumentation amp and pressure sensor seem to limit the maximum gain. I may try a variable amp reference voltage to eliminate these offsets. I bought some pressure transmitters from eBay to see if their noise levels are lower: an MKS Baratron 223B and an Ashcroft XLDP. Unfortunately these transmitters use a lot more power and voltage than I can steal from the PC serial port. Kits: If there is some interest I will offer a kit for this microbarograph. It would be similar to my seismometer kit that is described below, including step-by-step building instructions : http://www.infiltec.com/seismo/infkqm10.htm The seismometer kit was recently built by an 8th grader for her science project. Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: $200 microbarograph first light From: "John D Nelson" jnelson@................. Date: Mon, 9 Jan 2006 14:19:19 -0600 I would certainly be interested in seeing a kit offered, or at least the circuit board. John Nelson -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of David Saum Sent: Monday, January 09, 2006 2:08 PM To: Undisclosed-Recipient:; Subject: $200 microbarograph first light I finally got my $200 home-brew microbarograph running yesterday, and here are some pictures: Here is last night's data logged and plotted hourly with the seismic freeware AMASEIS. Time is GMT. Bandpass 0.01 Hz to 4.5 Hz. http://www.infiltec.com/Infrasound@................. The microbarograph was in a cooler, outside on the 4th=20 floor deck of my condo, with no spatial wind averaging array.=20 I am about 10 miles from Washington Reagan airport, and they reported 9-15mph winds, so the peaks are probably wind and not seismic events, nuclear tests, meteors, etc. :( Here is some fine structure of one of last night's events: http://www.infiltec.com/Infrasound@................. The adc pressure resolution is about 0.004 Pa, so a 200 adc=20 count peak is about 0.8 Pa. AMASEIS allows you to block any time segment and examine it in detail, including fourier transform and bandpass filtering. Exterior of microbarograph with serial cable: http://www.infiltec.com/Infrasound@................. Interior of microbarograph: http://www.infiltec.com/Infrasound@................. PCB removed from box http://www.infiltec.com/Infrasound@................. PCB and high-pass pneumatic filter removed from box: http://www.infiltec.com/Infrasound@................. System specs:=20 System Bandpass: 0.01 to 4 Hz. High-Pass filter: ~100 sec or 0.01 Hz using volume/capillary tube. Low pass filter: 4 Hz anti-alias, 8 pole Bessel filter (MAX4701) Differential pressure sensor: silicon, bridge type, 1"wc (DUXL01D) Pres Resolution: ~0.004 Pa - possibly lower depending offsets Range: +/- 120 Pa (32768 times pressure resolution) Amp: instrumentation,1000x,single supply,micropower,RTR out(INA122P)=20 Power: ~2ma 5VDC, derived from PC serial port, no exernal power supply Regulator: 5VDC, low dropout micropower, precision (LP2950-5.0) =20 Amplifer Reference Voltage: 2.5VDC fixed, precision reference (LT1004-2.5) Microprocessor: 4mhz, onboard 16 bit ADC and serial I/O (PIC14000) Firmware: ADC sampling at ~35 SPS, zero drift tracking ~5 min TC. Enclosure: diecast aluminum box for shielding (Hammond 1590P) Serial Out: RS232, 9600 baud, 8N1, ascii records, -32767 to +32767 Wind Spatial Averaging: array of micro-perforated garden tubing=20 Data Log/Display: freeware PC AMASEIS seismic log/analysis software Improvements?: Offset voltages in the instrumentation amp and pressure sensor seem to limit the maximum gain. I may try a variable amp reference voltage to eliminate these offsets. I bought some pressure transmitters from eBay to see if their noise levels are lower: an MKS Baratron 223B and an Ashcroft XLDP. Unfortunately these transmitters use a lot more power and voltage than I can steal from the PC serial port. Kits: If there is some interest I will offer a kit for this microbarograph. It would be similar to my seismometer kit that is described below, including step-by-step building instructions : http://www.infiltec.com/seismo/infkqm10.htm The seismometer kit was recently built by an 8th grader for her science project. Dave=20 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: $200 microbarograph first light From: "James Hannon" jmhannon@......... Date: Mon, 9 Jan 106 14:26:33 CST Dave, Looks real nice. I was wondering about the high pass filter. The capillary tube seems large. Did you arrive at the volume/ tube dia/ length by calculation or experiment? Do you have any data on these parameters vs response? Jim Hannon -- Jim Hannon http://www.fmtcs.com/web/jmhannon/ 42,11.90N,91,39.26W WB0TXL -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Recorded two 3 ricther scale earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 10 Jan 2006 02:09:29 +0000 Hi all Thanks to comment on how to increase the amptiude i did finally record earthquakes. This earthquakes are two, with just a few seconds time between them. The size according to i.m.o is 3,0Ml and 3,4Ml. The range from my station is about ~220 km. Below are gif image of the earthquake and the psn file. http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn.gif http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: $200 microbarograph first light From: ChrisAtUpw@....... Date: Mon, 9 Jan 2006 22:56:18 EST In a message dated 09/01/2006, DSaum@............ writes: Improvements? Offset voltages in the instrumentation amp and pressure sensor seem to limit the maximum gain. If you use a low noise differential input amplifier, but keep the gain at a level at which it does not saturate, you can add a high pass filter and then additional amplification and filtering. It can be a bit difficult to zero the sensor without increasing it's noise. In the equipment shown, the reference pressure is a very small volume connected to atmosphere with a leak tube. The temperature of the reference volume usually needs to be stabilised, to reduce ambient drift, especially when using a fairly long time constant, like 100 sec. A half pint thermos flask filled with the lightest grade of polyurethane foam makes quite a good reference. This allows the pressure sensing to be ~isothermal rather than semi adiabatic and increases the sensitivity. The ambient thermal response time of an empty flask is usually over 30 mins. The 'thermal mass' can be increased by adding candle wax inside the flask. The sensor shown will pick up wide band ambient noise from the wind, passing aircraft, helicopters, vehicles..... Unless you want to observe these sorts of signal, you can use a single stage pneumatic low pass filter, with a leak tube and a reference volume, to reduce the input noise. This may be quite helpful in keeping the output 'on scale', particularly in very windy / noisy conditions. Wind noise can be reduced by using a large sensor array of porous irrigation hose. This may be protected from rain to keep the acoustic properties fairly constant. A large circle of hose connected to a sensor at the centre by four to eight hard wall connecting tubes has been used for infrasound arrays, with diameters up to several hundred feet. Radial spokes of porous hose are also used, usually connected to the sensor with lengths of solid tube. It is also possible to use a single sensor head with a multi hole entry in between horizontal disks. This can significantly reduce the wind noise. Buildings, isolated trees, water towers, pylons etc will all have downwind vortices associated with them which can greatly increase the input signal amplitude at a 'miss-placed' sensor, usually to over twice the crosswind dimension. The turbulence generated by a structure like a wall or a hedge may be detected at distances over 50x the height downwind. Regards, Chris Chapman

In a message dated 09/01/2006, DSaum@............ writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Improvements? Offset voltages in the instrumentation amp and=20 pressure
sensor seem to limit the maximum=20 gain.

    If you use a low noise differential input=20 amplifier, but keep the gain at a level at which it does not saturate, you c= an=20 add a high pass filter and then additional amplification and filtering. = ;It=20 can be a bit difficult to zero the sensor without increasing it's=20 noise.

    In the equipment shown, the reference pressure=20= is a=20 very small volume connected to atmosphere with a leak tube. The tempera= ture=20 of the reference volume usually needs to be stabilised, to reduce ambient dr= ift,=20 especially when using a fairly long time constant, like 100 sec. A half= =20 pint thermos flask filled with the lightest grade of polyurethane foam makes= =20 quite a good reference. This allows the pressure sensing to be ~isother= mal=20 rather than semi adiabatic and increases the sensitivity. The ambient therma= l=20 response time of an empty flask is usually over 30 mins. The 'thermal m= ass'=20 can be increased by adding candle wax inside the flask.

    The sensor shown will pick up wide band ambient= =20 noise from the wind, passing aircraft, helicopters, vehicles..... Unless you= =20 want to observe these sorts of signal, you can use a single stage pneumatic=20= low=20 pass filter, with a leak tube and a reference volume, to reduce the inp= ut=20 noise. This may be quite helpful in keeping the output 'on scale', particula= rly=20 in very windy / noisy conditions.

    Wind noise can be reduced by using a large sens= or=20 array of porous irrigation hose. This may be protected from rain to keep the= =20 acoustic properties fairly constant. A large circle of hose connected to a=20 sensor at the centre by four to eight hard wall connecting tubes has be= en=20 used for infrasound arrays, with diameters up to several hundred feet. Radia= l=20 spokes of porous hose are also used, usually connected to the sensor with=20 lengths of solid tube.

    It is also possible to use a single sensor head= =20 with a multi hole entry in between horizontal disks. This can significa= ntly=20 reduce the wind noise. Buildings, isolated trees, water towers, pylons=20= etc=20 will all have downwind vortices associated with them which can greatly incre= ase=20 the input signal amplitude at a 'miss-placed' sensor, usually to over twice=20= the=20 crosswind dimension. The turbulence generated by a structure like a wal= l or=20 a hedge may be detected at distances over 50x the height downwind.

    Regards,

    Chris Chapman
Subject: ebay auction From: Bob Barns royb1@........... Date: Tue, 10 Jan 2006 10:38:15 -0500 GeoSonics SSU Micro Seismograph Earthquake System Unit Item number: 7579963838 ends 1/16 Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Locating P and S wave, suggestions needed From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 10 Jan 2006 17:53:25 +0000 Hi all As I did say in my early post today, I did record a earthquake at 00:25 today. The earthquake mag was 3,0 on the ricther scale according to the icelandic met office. My problem is this that i don't think i have found the p and s wave properly, since this earthquake wave has two spikes, not one. I did think that i had correctly located the p and s waves, but based on the wave form I am not totally sure. Here is the gif file and the psn file of the recording. http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn.gif http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn (p and s markers are not set in this psn file) Here is a picture of the earthquake with the p and s markers as i did set them. http://alvaran.com/forum/index.php?act=Attach&type=post&id=11 If nothing else, I welcome suggestions on this matter. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: $200 microbarograph first light From: ChrisAtUpw@....... Date: Tue, 10 Jan 2006 21:49:34 EST In a message dated 09/01/2006, DSaum@............ writes: System Bandpass: 0.01 to 4 Hz. High-Pass filter: ~100 sec or 0.01 Hz using volume/capillary tube. Low pass filter: 4 Hz anti-alias, 8 pole Bessel filter (MAX4701) This gives a drop of 40 dB at 4 Hz, an average signal delay of 0.2 sec and 0.35 sec peak. Differential pressure sensor: silicon, bridge type, 1"wc (DUXL01D) Pres Resolution: ~0.004 Pa - possibly lower depending offsets Range: +/- 120 Pa (32768 times pressure resolution) For a 5 V supply, this sensor has an output of 6 mV per inch water and a span of 6 mV. You might do better with a DUXL05D. This has an output of 4.5 mV per inch water and a span of 22.5 mV. 1" water gauge corresponds to a pitot speed of about 45 mph. This does not leave much, if any, safety margin for storm conditions. Amp: instrumentation,1000x,single supply,micropower,RTR out(INA122P) While the INA122 has rail to rail output, it also has a 0.1 to 10 Hz noise of 2 micro V pp. This is poor in comparison with an INA118 which has a noise level of 0.28 micro V pp - roughly 1/7th. There are other low noise opamps available. Power: ~2ma 5VDC, derived from PC serial port, no exernal power supply Regulator: 5VDC, low dropout micropower, precision (LP2950-5.0) Firmware: ADC sampling at ~35 SPS, zero drift tracking ~5 min TC. Serial Out: RS232, 9600 baud, 8N1, ascii records, -32767 to +32767 Wind Spatial Averaging: array of micro-perforated garden tubing Data Log/Display: freeware PC AMASEIS seismic log/analysis software Improvements? Offset voltages in the instrumentation amp and pressure sensor seem to limit the maximum gain. I may try a variable amp reference voltage to eliminate these offsets. Use the average signal level as your zero? Regards, Chris Chapman
In a message dated 09/01/2006, DSaum@............ writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>System=20 Bandpass: 0.01 to 4 Hz.
High-Pass filter: ~100 sec or 0.01 Hz using=20 volume/capillary tube.
Low pass filter: 4 Hz anti-alias, 8 pole Bessel=20 filter (MAX4701)
    This gives a drop of 40 dB at 4 Hz, an average=20 signal delay of 0.2 sec and 0.35 sec peak.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Differential pressure sensor: silicon, bridge type, 1"wc=20 (DUXL01D)
Pres Resolution: ~0.004 Pa - possibly lower depending=20 offsets
Range: +/- 120 Pa (32768 times pressure=20 resolution)
    For a 5 V supply, this sensor has an output of=20= 6 mV=20 per inch water and a span of 6 mV. You might do better with a DUXL05D.=20= This=20 has an output of 4.5 mV per inch water and a span of 22.5 mV.

    1" water gauge corresponds to a pitot speed of=20 about 45 mph. This does not leave much, if any, safety margin for storm= =20 conditions.

Amp: instrumentation,1000x,single supply,micropower,RTR out(INA= 122P)=20

    While the INA122 has rail to rail output, it al= so=20 has a 0.1 to 10 Hz noise of 2 micro V pp. This is poor in comparison with an= =20 INA118 which has a noise level of 0.28 micro V pp - roughly 1/7th. There are= =20 other low noise opamps available.

Power: ~2ma 5VDC, derived from PC serial port, no exernal power=20 supply
Regulator: 5VDC, low dropout micropower, precision (LP2950-5.0)&nb= sp;=20
Firmware: ADC sampling at ~35 SPS, zero drift tracking ~5 min TC.
Ser= ial=20 Out: RS232, 9600 baud, 8N1, ascii records, -32767 to +32767
Wind Spatial=20 Averaging: array of micro-perforated garden tubing
Data Log/Display:=20 freeware PC AMASEIS seismic log/analysis software

Improvements? Offse= t=20 voltages in the instrumentation amp and pressure
sensor seem to limit the= =20 maximum gain. I may try a variable amp reference
voltage to elimina= te=20 these offsets.

    Use the average signal level as your=20 zero?

    Regards,

    Chris Chapman

Subject: Re: Locating P and S wave, suggestions needed From: Paul elegant_dice@......... Date: Wed, 11 Jan 2006 09:44:25 +0800 According to my friend, he reckons they look good. Your S looks good to him, but your P could be moved to coincide with the peak of the first pulse, it seems to be a few samples earlier than the peak. I'm new at this myself, so I'd like to hear some feedback too J�n Fr�mann wrote: > Hi all > > As I did say in my early post today, I did record a earthquake at 00:25 > today. The earthquake mag was 3,0 on the ricther scale according to the > icelandic met office. My problem is this that i don't think i have found > the p and s wave properly, since this earthquake wave has two spikes, > not one. I did think that i had correctly located the p and s waves, but > based on the wave form I am not totally sure. > > Here is the gif file and the psn file of the recording. > http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn.gif > http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn > (p and s markers are not set in this psn file) > > Here is a picture of the earthquake with the p and s markers as i did > set them. > http://alvaran.com/forum/index.php?act=Attach&type=post&id=11 > > If nothing else, I welcome suggestions on this matter. > > Regards. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Locating P and S wave, suggestions needed From: "Bob Hancock" carpediem1@......... Date: Tue, 10 Jan 2006 21:40:09 -0700 I downloaded the file and then looked at it with the FFT option in = WinQuake. I tried several different filtering options and then settled on = filtering out all data with a frequency longer than 1 hz. I was unable to see anything that looked like an earthquake in the longer frequencies. This appears to be two separate earthquakes such as a primary event and aftershock, rather than a P wave and S wave. In addition, based upon = the higher frequencies of both events, they are relatively close to the = station, although I would not want to hazard a guess at distance. I have noticed similar frequencies from nearby events both in New Jersey where I used = to live and now in Arizona. =20 The initial direction of what I perceived as the P wave is visible and = moves up on both events. As I see it, the first event occurred at 25:53.270 = and the amplitude on the P wave was 20.3. The second event occurred at 26:13.120, and the amplitude on the P wave was 34.6. This all becomes visible when you filter out the lower frequency data, = and expand the X axis to 10 seconds. However, if an expert has a better answer, I will bow to them. Bob Hancock Three Points, AZ -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of Paul Sent: Tuesday, January 10, 2006 18:44 To: psn-l@.............. Subject: Re: Locating P and S wave, suggestions needed According to my friend, he reckons they look good. Your S looks good to = him, but your P could be moved to coincide with the peak of the first=20 pulse, it seems to be a few samples earlier than the peak. I'm new at this myself, so I'd like to hear some feedback too J=F3n Fr=EDmann wrote: > Hi all >=20 > As I did say in my early post today, I did record a earthquake at = 00:25 > today. The earthquake mag was 3,0 on the ricther scale according to = the > icelandic met office. My problem is this that i don't think i have = found > the p and s wave properly, since this earthquake wave has two spikes, > not one. I did think that i had correctly located the p and s waves, = but > based on the wave form I am not totally sure. >=20 > Here is the gif file and the psn file of the recording. > http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn.g= if > = http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn > (p and s markers are not set in this psn file) >=20 > Here is a picture of the earthquake with the p and s markers as i did > set them. > http://alvaran.com/forum/index.php?act=3DAttach&type=3Dpost&id=3D11 >=20 > If nothing else, I welcome suggestions on this matter. >=20 > Regards. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Locating P and S wave, suggestions needed From: John or Jan Lahr JohnJan@........ Date: Tue, 10 Jan 2006 21:01:36 -0800 Hi J=F3n, To get better resolution in time, change the time=20 window (x scale) to 40 seconds. Then use the Display/Modify system to enter the=20 known location, origin time, and magnitude from=20 the Iceland network (http://hraun.vedur.is/ja/englishweb/eqlist.html). Click on the Loc button and the P and S markers=20 will be positioned automatically. When I did=20 this they were close to the start of the phases,=20 but a one or two seconds late. This could mean=20 that your clock is a few seconds fast, or that=20 the velocity model does not fit exactly for Iceland. When I position the P and S markers, the implied=20 distance is 162 km, whereas the computed distance=20 is 166 km. This is pretty close. I think you recorded the 3.4 event rather than=20 the 3.0 event, but it can be hard to untangle=20 events that are this close together in space and time. 20= 06-01-1000:25:26,563,964-21,8541,13,490,03=20 5,1 kmSof Helgafell 20= 06-01-1000:25:24,963,955-22,1133,23,090,05=20 7,9 kmNNWof Kr=EDsuv=EDk I posted my WinQuake windows showing the way I would pick this earthquake= here: http://jclahr.com/science/psn/misc/jon.html Cheers, John At 09:53 AM 1/10/2006, you wrote: >Hi all > >As I did say in my early post today, I did record a earthquake at 00:25 >today. The earthquake mag was 3,0 on the ricther scale according to the >icelandic met office. My problem is this that i don't think i have found >the p and s wave properly, since this earthquake wave has two spikes, >not one. I did think that i had correctly located the p and s waves, but >based on the wave form I am not totally sure. > >Here is the gif file and the psn file of the recording. >http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn.gif >http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn >(p and s markers are not set in this psn file) > >Here is a picture of the earthquake with the p and s markers as i did >set them. >http://alvaran.com/forum/index.php?act=3DAttach&type=3Dpost&id=3D11 > >If nothing else, I welcome suggestions on this matter. > >Regards. >-- >J=F3n Fr=EDmann J=F3nsson >http://www.jonfr.com > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. ##################################/ John C. Lahr #################################/ Emeritus Seismologist ################################/ U.S. Geological Survey =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D/ Geologic Hazards Team ##############################/ Golden, Colorado #############################//############################## ############################//############################### PO Box 548 /################################ Corvallis, Oregon 97339 /################################## Phone: (541) 758-2699 /=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Cell: (541) 740-4844 /################################### Fax: (928) 569-0113 /################################## jjpub@........ /#################################### http://jclahr.com/science/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Locating P and S wave, suggestions needed From: John or Jan Lahr JohnJan@........ Date: Tue, 10 Jan 2006 21:08:42 -0800 Bob may be right about this being two events. As soon as there is another 3.5 event within 175 km of Jon's station, it will be clear if he is able to see it clearly. If not, then that would argue for the two-event interpretation. The separation of the two phases is very close to what would be expected for the S-P interval from the distant events, so that argues for my interpretation. John At 08:40 PM 1/10/2006, you wrote: >This appears to be two separate earthquakes such as a primary event and >aftershock, rather than a P wave and S wave. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Locating P and S wave, suggestions needed From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 11 Jan 2006 06:14:37 +0000 Hi all Thanks for the comments and suggestions, i am sure that i will learn this with time. I did go over the final resaults of this earthquake on the Icelandic met Office homepage and according to that resaults they only register one earthquake at that exact time, the size of the evenent was 3.07 M. Here is the final resaults from I.M.O. I took also few smaller earthquakes that i didn't detect. Those earthquakes where few seconds before the earthquake that i did detect. Depth M Ml 9 20060110 002459.128 63.94168 -22.10622 5.094 0.76 0.16 10 20060110 002506.566 63.94402 -22.10538 4.168 0.46 -0.02 11 20060110 002525.044 63.94730 -22.11069 5.103 3.07 2.57 12 20060110 002641.410 63.93540 -22.11102 6.147 1.32 0.42 The page that has this info is in Icelandic, it is not on there engish web. Why this earthquake shows two spikes is something i don't understand. But that is problay the reasion why IMO automatic system shows two earthquakes. The p and s wave diffrance is 20.7 sec, when i did put in the final resaults from the Icelandic met Office. At this range i seems to be able to detect earthquakes down to 3 on the ricther scale. The area where this earthquake was, often has earthquakes that are from 3 - 5 on the ricther scale. So i might not have to wait so long for other earthquake to happen, in order to see the diffrance on earthquakes. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Locating P and S wave, suggestions needed From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 11 Jan 2006 08:43:53 +0000 Hi all I have all the psn files and gifs for those who don't have winquake. Just follow the urls. This is with the data from IMO and p and s markers set. http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424p.s.mark.ch1.gif http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424p.s.mark.ch2.gif http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424p.s.mark.ch3.gif http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch3.psn http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch2.psn http://www.simnet.is/jonfr500/earthquake/winquake/060110.002424.ch1.psn When looked at the N-S file (ch3) the wave appears just to have one earthquake the same applyes to E-W (ch2), boths channels pattern is alot diffrent then from Z (ch1). Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: $200 microbarograph first light From: "Arie Verveer" greensky@.............. Date: Wed, 11 Jan 2006 21:48:55 +0800 David, A few year ago I ran an infra-sound detector and found the air currents caused a great deal of problems. Basically most of the signal. Only having a limited space, I opted for a long length of thin wall silicon tube coiled in a spiral. This tube was purchased from a medical supplier. It acted a a large diaphragm reducing the air currents at the detectors input. I managed to detect the air pressure induced by the movement of a small local quake (100 km away) that shook the ground under the detector. A few observed meteors were detected plus some interesting yearly changes in the background noise (ocean). I do think the radial arm on porous tubes close to the ground would be the best way forward assuming you have the space. My detector operated 10 hz and lower. On the drawing board is mark three of the detector but before I attempted this I wrote a program that calculated the propagation of infra-sound in the earth's atmosphere. It's a working program but not polished enough for production. If you are interested I can send you some image plots on wave propagation. It explains why a local quakes infra-sound may bounce right over your location and why thunderstorms can only be heard a certain distance and so on. Question: can image files be posted to this site ? Its been a while since I last posted anything. It would be good to have a network of these sensors. Great work. Cheers Arie __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Can i use any of those programs ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 11 Jan 2006 13:56:22 +0000 Hi all Can is use any of those programs on this list with the psn board that i have or with winsdr. http://quake.wr.usgs.gov/research/software/ Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: $200 microbarograph first light From: John Popelish jpopelish@........ Date: Wed, 11 Jan 2006 15:14:14 -0500 Arie Verveer wrote: > David, > > A few year ago I ran an infra-sound detector and found > the air currents caused a great deal of problems. > Basically most of the signal. Only having a limited > space, I opted for a long length of thin wall silicon tube > coiled in a spiral. This tube was purchased from a medical > supplier. It acted a a large diaphragm reducing the air > currents at the detectors input. I managed to detect > the air pressure induced by the movement of a small local > quake (100 km away) that shook the ground under the detector. > A few observed meteors were detected plus some interesting > yearly changes in the background noise (ocean). I do think the > radial arm on porous tubes close to the ground would be > the best way forward assuming you have the space. My > detector operated 10 hz and lower. (snip) Do you have any idea what your pressure transducer's sensitivity to acceleration is? Unless it is a balanced design that specifically cancels the effects of acceleration, you may have seen a signal that was a combination of pressure and sensor movement. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: $200 microbarograph first light From: "Arie Verveer" greensky@.............. Date: Thu, 12 Jan 2006 20:05:16 +0800 Hi, The Pressure sensor is a MKS Bartatron Type 223B 0.2 mmHg Full scale range. It's taut metal diaphragm was placed parallel to the ground and I would guess it's response to acceleration is quickly dampened, far above the 10 Hz response. As my station was some 120km from our local seismic field direct (distant) measurement from a local quake was not possible. The infra-sound will propagate up-wards and then refracts back to the detector some 200 - 250 km away. I only detected events as the atmosphere was displaced above the sensor. Cheers Arie On Thu, 12 Jan 2006 04:14:14 +0800, John Popelish wrote: > Arie Verveer wrote: >> David, >> >> A few year ago I ran an infra-sound detector and found >> the air currents caused a great deal of problems. >> Basically most of the signal. Only having a limited >> space, I opted for a long length of thin wall silicon tube >> coiled in a spiral. This tube was purchased from a medical >> supplier. It acted a a large diaphragm reducing the air >> currents at the detectors input. I managed to detect >> the air pressure induced by the movement of a small local >> quake (100 km away) that shook the ground under the detector. >> A few observed meteors were detected plus some interesting >> yearly changes in the background noise (ocean). I do think the >> radial arm on porous tubes close to the ground would be >> the best way forward assuming you have the space. My >> detector operated 10 hz and lower. > (snip) > > Do you have any idea what your pressure transducer's sensitivity to > acceleration is? Unless it is a balanced design that specifically > cancels the effects of acceleration, you may have seen a signal that > was a combination of pressure and sensor movement. > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Finetuning L15B geophone From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 12 Jan 2006 14:29:01 +0000 Hi all The new guy in this earthquake stuff needs help agen. I want to finish setup my geophone settings in winsdr, but i don't know what values i need to insert in this settings box in winsdr. Azimuth, currently set to 0, Incident, set to 0, Output Voltage, set to 0, Amp gain, set to 0, A/D input, set to 0, Sensitivity, set to 0, WinQuake Mag Corr, set to 0, Filter delay, set to 0, DC offset, set to 0. I need to know how to fill those 0 with numbers that are useful to me. Or a good how-to on it. (I have read the help files, but i am still shorta lost on this) I also need to know what unit is on the mesurment, when earthquakes are detected. Since i was sending my recording to one geologist at the Icelandic met Office and she did want to know what the setting was on the detection when earthquake is detected. Then the units that are used, she did come with this numbers, "24, 48, 72 .....". I hate know almost nothing about this at this time, i hope pepole here can tolirate my endless questions. Becose i am learning this day by day. Greetings. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthquake monitoring in Iceland/Scotland/ and the US From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 12 Jan 2006 15:49:03 +0000 Hi all Sorry for bringin this old disccuion back up from the darkness of time. I have found out how far away from a solid rock my geophone is, it is not deeper then 2m at the most, we are speaking about 2m of sand below the concret floor then just solid rock. It problay is a lot less then that below my apartment (i am on ground floor), but it is hard to say for sure. Greetings. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthquake monitoring in Iceland/Scotland/ and the US From: "Thomas Dick" dickthomas01@............. Date: Thu, 12 Jan 2006 12:27:00 -0600 I wish I had only 2 meters to bed rock. I'd take a shovel and dig that far. It is at least 60 meters to bedrock here at my location. I have to worry more about liquifraction! __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthquake monitoring in Iceland/Scotland/ and the US From: "Geoff" gmvoeth@........... Date: Thu, 12 Jan 2006 17:44:23 -0700 You think you got troubles I am like 240 meters from beadrock and I have a major road only 30 or so meters away. I have heard you do not want roads any closer then the bedrock is deep. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: microbarograph sensor arrays From: ChrisAtUpw@....... Date: Thu, 12 Jan 2006 22:27:16 EST Hi, There is a very useful Jan 2005 Revue Article by A J Bedard on Infrasonic Signals of many sorts and their characteristics at _http://www.etl.noaa.gov/et1/infrasound/Monthly_Weather_Rev_Paper_Jan05.pdf_ (http://www.etl.noaa.gov/et1/infrasound/Monthly_Weather_Rev_Paper_Jan05.pdf) There are other useful links at _http://www.etl.noaa.gov/et1/infrasound/_ (http://www.etl.noaa.gov/et1/infrasound/) Apparatus is described at _http://www.tornadochaser.net/research/infasonicdetector.pdf_ (http://www.tornadochaser.net/research/infasonicdetector.pdf) The reduction of wind noise is the major problem when trying to receive infrasound signals. Large sensor arrays of 'leaky tube' of up to several hundred feet in diameter may be used. For a single sensor head see US Patent No 4,838,087 June 1989, Bedard and Nishiyama, 'Quad Disk Static Pressure Probe'. Regards, Chris Chapman
Hi,

    There is a very useful Jan 2005 Revue Article b= y A=20 J Bedard on Infrasonic Signals of many sorts and their characteristics at=20 http://www.etl.noaa.gov/et1/infrasound/Monthly_Weather_Rev_Paper_Jan= 05.pdf

    There are other useful links at http://www.etl.noaa.gov/et1= /infrasound/

    Apparatus is described at http://= www.tornadochaser.net/research/infasonicdetector.pdf

    The reduction of wind noise is the major proble= m=20 when trying to receive infrasound signals. Large sensor arrays of 'leaky tub= e'=20 of up to several hundred feet in diameter may be used. For a single sen= sor=20 head see US Patent No 4,838,087 June 1989, Bedard and Nishiyama, 'Quad=20= Disk=20 Static Pressure Probe'.

    Regards,

    Chris Chapman
Subject: I did record a 3,6Ml earthquake, 198 Km away from me. From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 13 Jan 2006 16:19:06 +0000 Hi all I did just record a 3,6Ml earthquake at 15:19 today. You can get the psn file here. http://www.simnet.is/jonfr500/earthquake/winquake/060113.151900.ch1.psn Here is the gif file. At the moment it does not have any p and s markers. http://www.simnet.is/jonfr500/earthquake/winquake/060113.151900.ch1.psn.gif I have inserted the early time data from IMO into the psn file. I have not done so with N-S, E-W files. But i will do so later tonight. It is intresting to compare this one with the mag 3,0 that did happen 10th of January that was south of me at distance of 171 km. This one was east of me and 198km away from me. It is also clearly visable on my raw seismographs. Greetings. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: I did record a 3,6Ml earthquake, 198 Km away from me. From: John or Jan Lahr JohnJan@........ Date: Fri, 13 Jan 2006 08:53:27 -0800 J=F3n, You're lucky to be in an active area (at least in=20 terms of recording lots of local activity). In your gif images, if you expand the time scale=20 by setting the time interval to something=20 shorter, such as 30 seconds, the event details=20 will be more easily seen and picks will be more accurate. Cheers, John At 08:19 AM 1/13/2006, you wrote: >Hi all > >I did just record a 3,6Ml earthquake at 15:19 today. You can get the psn >file here. > >http://www.simnet.is/jonfr500/earthquake/winquake/060113.151900.ch1.psn > >Here is the gif file. At the moment it does not have any p and s >markers. > >http://www.simnet.is/jonfr500/earthquake/winquake/060113.151900.ch1.psn.gif > >I have inserted the early time data from IMO into the psn file. I have >not done so with N-S, E-W files. But i will do so later tonight. It is >intresting to compare this one with the mag 3,0 that did happen 10th of >January that was south of me at distance of 171 km. This one was east of >me and 198km away from me. It is also clearly visable on my raw >seismographs. > >Greetings. >-- >J=F3n Fr=EDmann J=F3nsson >http://www.jonfr.com > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. ##################################/ John C. Lahr #################################/ Emeritus Seismologist ################################/ U.S. Geological Survey =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D/ Geologic Hazards Team ##############################/ Golden, Colorado #############################//############################## ############################//############################### PO Box 548 /################################ Corvallis, Oregon 97339 /################################## Phone: (541) 758-2699 /=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Cell: (541) 740-4844 /################################### Fax: (928) 569-0113 /################################## jjpub@........ /#################################### http://jclahr.com/science/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: I did record a 3,6Ml earthquake, 198 Km away from me. From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 13 Jan 2006 17:00:43 +0000 Hi John or Jan Lahr Updated gif image with p and s markers will be online in just a moments time (few min after i send this email). I have used early data from IMO to set the p and s markers. Greetings. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: I did record a 3,6Ml earthquake, 198 Km away from me. From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 13 Jan 2006 17:15:28 +0000 Hi all I have updated the files with final data from IMO webapge. I haven't posted E-W or N-S files. If you want them, just let me know. Bye. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: I did record a 3,6Ml earthquake, 198 Km away from me. From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 13 Jan 2006 22:52:25 +0000 Hi John There has not been a earthquake swarm in past three weeks since i got the geophone (not large anyway), but they are common here in Iceland. Most of them happen in the Tj�rnes Fracture Zone (TFZ), but they are also common on the Reykjanes ridge and the Reykjanes it self (where Reykjavik is located) and other locations in Iceland on the volcano ridge. Sometimes earthquakes that go to 5mb happen. But most common are earthquakes in the range of 3 - 4,9Ml. I am speaking of earthquake swarms with hundreds of earthquakes pr hour and sometimes thousunds of earthquakes pr hour and more then a dosent of earthquakes that rech 3 - 4Ml in size, sometims more. That has not happened, but when it happens my online graphs are going to look quite inresting. :-) Greetings. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: I did record a 3,6Ml earthquake, 198 Km away from me. From: "Bob Shannon" earth@........... Date: Fri, 13 Jan 2006 15:05:36 -0800 Just out of curiosity, were you able to pick this up?: 4.0 2006/01/13 04:10:18 18.685 -65.038 54.5 PUERTO RICO REGION -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of J=F3n Fr=EDmann Sent: Friday, January 13, 2006 2:52 PM To: psn-l@.............. Subject: Re: I did record a 3,6Ml earthquake, 198 Km away from me. Hi John There has not been a earthquake swarm in past three weeks since i got the geophone (not large anyway), but they are common here in Iceland. Most of them happen in the Tj=F6rnes Fracture Zone (TFZ=20 --=20 No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.371 / Virus Database: 267.14.16 - Release Date: 1/9/2006 =20 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: I did record a 3,6Ml earthquake, 198 Km away from me. From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 13 Jan 2006 23:14:02 +0000 Hi Bob Shannon No, i don't have a teleseismic sensor yet. I only have a short range geophone, that works on 4,5Hz and has a max distance of ~640km. My online seismographs are here, the earthquake today is clearly visable even there is a alot of noise that the geophone picks up. http://www.simnet.is/jonfr500/earthquake/ The earthquake was at 15:19 Greetings. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auction From: Bob Barns royb1@........... Date: Sat, 14 Jan 2006 09:40:17 -0500 Hi gang, Impact-O-Graph - Recording Accelerometer - Seismograph? Item number: 7581594696 ends 1/18 Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Earthquake in Beaufort Sea, 4.9mb From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 14 Jan 2006 14:59:02 +0000 Hi all I did notice that according to emsc-csem that today there was a earthquake in Beaufort Sea, the size of the earthquake was at least 4,9mb. I find the location of the earthquake intresting, since there is no active faultline there or other type of active area that know of. Here is the info on the earthquake from emsc-csem. http://www.emsc-csem.org/cgi-bin/QDM_link_content.sh?HC308&2006 Bye. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auction From: Bob Barns royb1@........... Date: Mon, 16 Jan 2006 10:05:21 -0500 Hi gang, SEISMOGRAPH MINI -MATE Item number: 6245357035 ends 1/22 Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auction From: Bob Barns royb1@........... Date: Tue, 17 Jan 2006 09:37:02 -0500 Hi gang, Vintage Seismograph Seiscor Telephone Test Set - L@@k! Item number: 6597839335 ends 1/23 I have no idea what this is. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: follow-up From: "Thomas Dick" dickthomas01@............. Date: Wed, 18 Jan 2006 16:55:40 -0600 I understand from witnesses of the Nov 6 tornado over here in Evansville = that as many as four from your office came to the area. Was a formal = report of their findings ever released?
I understand from witnesses of the Nov = 6 tornado=20 over here in Evansville that as many as four from your office came to = the area.=20 Was a formal report of their findings ever released?

Subject: Earthquake swarm From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 19 Jan 2006 16:21:28 +0000 Hi all At the current moment there appears to be earthquake swarm going on in North East of Iceland, north of Krafla volcano system. The biggest earthquake so far is 4,1Ml. But unfortunally i was moving my geophone outside when the earthquake did happen, so i did only got the tail of it. Also, becose i did move the geophone outside the dection is alot better and i can now see car traffic alot "better" then i did before. But it hopefully will not be alot of problem for me. Bye. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Stand Alone A/D converter From: "Geoff" gmvoeth@........... Date: Thu, 19 Jan 2006 19:15:19 -0700 Hello you eggheads; Not trying to offend anyone it is just an affectionate term I use for academically oriented person/persons. The results following this question might be of interest for newbie Amateurs just getting into this sport I would like to have known the answer to this question 10 years ago. I got this problem that can only be solved by someone with experience with the exact/precise thing of which I speak here. I am in need of a stand alone 16 bit A/D converter that can interface with an IBM style laptop via parallel/serial/USB ports. It must be totally controllable via the laptop for sample rates meaning the trigger for each sample to be read is to be ordered by the laptop running a custom built program. It needs to acquire data at the rate of 100 samples per second or slower. It needs to be quiet down to the last LSb so the entire 16 bit word can be used. It needs to provide -120dbv or so isolation between (the computer and/or the power supply) and the input to the converter. I have tried only one A/D converter a model 40-12 by a company called Prairie Digital out of Du Sac, WI this device seems to lack the isolation I need and also radiates terribly its color burst clock frequency. It is relatively noisy forcing me to use only the top 9 bits of its 12 bit capability. This device is pretty much what I am looking for in a converter but just too darn noisy. If any of you kind folks out there will please take mercy on my soul and tell me where I can find a device like this Prairie Digital but designed for serious (quiet) data collection I sure would like to know. Please feel free to answer me direct via gmvoethhotmail.com . I have looked around and found a mess of internal cards to plug into a computer but What I am looking for is a stand alone device which one of you seismic gurus have used before with excellent results. One which can be outfitted with battery backup. Thanx Ahead Of Time; gmv p.s. this question is not designed to cause any troubles I was just wondering if any of you out there know this off the top of your head. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Stand Alone A/D converter From: John or Jan Lahr JohnJan@........ Date: Thu, 19 Jan 2006 20:06:00 -0800 At 06:15 PM 1/19/2006, you wrote: >I am in need of a stand alone 16 bit >A/D converter Geoff, One option worth considering is the 24-bit A/D made by Symetric Technology. The owner is Kip Wyss and he's been designing A/D converters for 20 years. He sells a 1-channel system that connects via the parallel port and the cost is only $150. See: http://www.symres.com/products/seldaq.htm If you want very precise timing, then you can also get a GPS module, but that jumps the price up quite a bit. I've only spent a little time trying out the sample program that comes with the 1-channel system. You definitely have complete control over all aspects of the A/D, but I haven't gotten into any of the details. Hope this helps, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Noise that my geophone picks up From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 20 Jan 2006 21:59:34 +0000 Hi all I am wondering about noise on my geophone. I have moved my geophone outside so i have mostly got rid of the noise from inside the house. But now i get the noise from the weather, traffic and so on alot more then when it was inside my apartment. However i hope to detect earthquake better then i did before. But that remanins to be seen. I appreceate any comments on my noise level. The seismographs plot are set to setting 8 in winsdr, so it is not too crude. Bye. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise that my geophone picks up From: ChrisAtUpw@....... Date: Fri, 20 Jan 2006 18:25:37 EST In a message dated 20/01/2006, jonfr500@......... writes: I am wondering about noise on my geophone. I have moved my geophone outside so I have mostly got rid of the noise from inside the house. But now I get the noise from the weather, traffic and so on a lot more then when it was inside my apartment. However I hope to detect earthquake better then I did before. Hi Jon, Have you sealed the plastic case? Are the geophones above the ground surface, on the surface, or below the surface? Is there a container over the top? Is there any possibilty of digging a hole maybe 1 m deep and putting in a large diameter plastic pipe or similar, sealed at the top and the bottom? It needs to be completely weather proof. How do the actual noise levels compare with those when the geophones were in the apartment? Can you compare 'before' and 'after' recordings? A professional seismometer pit is described at _http://www.guralp.net/services/stations/eskdalemuir/_ (http://www.guralp.net/services/stations/eskdalemuir/) Regards, Chris Chapman

In a message dated 20/01/2006, jonfr500@......... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I am=20 wondering about noise on my geophone. I have moved my geophone
outside=20= so I=20 have mostly got rid of the noise from inside the house. But
now I=20= get=20 the noise from the weather, traffic and so on a lot more then
when it w= as=20 inside my apartment. However I hope to detect earthquake
better=20 then I did before.

Hi Jon,

    Have you sealed the plastic case? Are the geoph= ones=20 above the ground surface, on the surface, or below the surface? Is there a=20 container over the top?

    Is there any possibilty of digging a hole maybe= 1 m=20 deep and putting in a large diameter plastic pipe or similar, sealed at the=20= top=20 and the bottom? It needs to be completely weather proof.

    How do the actual noise levels compare with tho= se=20 when the geophones were in the apartment? Can you compare 'before' and 'afte= r'=20 recordings?

    A professional seismometer pit is described at=20= http://www.gur= alp.net/services/stations/eskdalemuir/

    Regards,

    Chris Chapman
Subject: Re: Noise that my geophone picks up From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 20 Jan 2006 23:48:17 +0000 Hi Chris The geophone is above ground, with double box on it, inside is a plastic box and on top of that is a wood box that has isolation material, i also have two heavy rocks on the box to prevent it from moving in bad weather. It is well sealed from the weather (as well it can be done). Digging a hole 1m deep is not an option for me, becose my lawn is shared and the there is a bedrock problay about 1m deep down, also the ground freezing line is about 1m deep. The noise pickup is diffrent, i see more wind but fewer spikes that start a warning in winsdr. Only the higest noise inside the block is now picked up in such way it starts a warning in winsdr (like when someone closes a door). Unlike before when i did pickup almost everything. It also seems when the weather is good, and there is no or little traffic the noise level go down to almost nothing (that seems to be the case at the moment). The only thing that creates alot of spikes is when the snow is cleared off the roads near me. But only when it is done close to my location, less then 500m away from me. So far the geophone has withstand a heat change from -5C to 3C in the past 24 hours. I can send a picture of my setup, if you are intrested in seeing it. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digital Inverse Filter From: Bobhelenmcclure@....... Date: Fri, 20 Jan 2006 22:50:58 EST In my email of December 31, 2005, I was pessimistic about digitally =20 extending the low frequency response of a geophone to a value useful for te= leseisms.=20 However, I have been encouraged by my experiments on data recorded by J=F3n= =20 Fr=EDmann J=F3nsson of Iceland. Please inspect the volume file=20 =20 "060117.015700.hvtzlp Mb4.5 259km from Hvammstangi, Iceland (Inverse=20 Filtered): REYKJANES RIDGE"=20 =20 which I have submitted to the New PSN Earthquake Data Files list. This is a= =20 volume file consisting of two traces. The upper trace is the result of =20 applying "WQFilter.exe" to the data of the bottom trace. You will see that =20= inverse=20 filtering has brought out microseisms and the longer period components of t= he=20 event. I set the Long Period filter to extend the sensor period from 0.22=20 seconds to 4.0 seconds. =20 Bob McClure
In my email of December 31, 2005, I was pessimistic about digita= lly=20 extending the low frequency response of a geophone to a value useful for=20 teleseisms. However, I have been encouraged by my experiments=20 on data recorded by J=F3n Fr=EDmann J=F3nsson of Iceland. Please i= nspect the=20 volume file

"060117.015700.hvtzlp Mb4.5 259km from Hvammstangi, Icelan= d=20 (Inverse Filtered): REYKJANES RIDGE"

which I have submitted to the New PSN Earthquake Data Files list.=20= This=20 is a volume file consisting of two traces. The upper trace is the result of=20 applying "WQFilter.exe" to the data of the bottom trace. You will see that=20 inverse filtering has brought out microseisms and the longer period=20 components of the event. I set the Long Period filter to extend th= e=20 sensor period from 0.22 seconds to 4.0 seconds.

Bob McClure
Subject: Re: Noise that my geophone picks up From: "Geoff" gmvoeth@........... Date: Fri, 20 Jan 2006 22:20:50 -0700 Are you the Frimann (Freeman) of Half Life two ??? If you are looking higher than two hertz you are probably plagued by all kinds of man made noises and if you are looking under one hertz you should find terrible microseisms about point two hertz. I find it best to limit things between point four hertz and two hertz if at all possible you want a flat response range in this area to see P waves. If you want to see P,S,L waves you need a flat response between point oh five and two hertz but then you will need to turn down your gain to avoid the added noise of a wide band receiver from all sources. I am in a terrible bad noisy place and considering trying a high gain narrow band receiver with a Q of 10 or so and centered on or just below 1 Hz to see only the P waves of teleseismic events. I would be interested in hearing from people who have battled the man made noises. I understand the quietest place you can put your Geophone is directly on bedrock but since bedrock might be 800 feet deep it is not an option I can try. All the noise I speak of is in the Southwest Desert of Arizona and (I understand) the noise profile is highly dependent upon geographics. For all you experts, I just want to share my personal experiences here as a layman I am not trying to supersede your efforts to maintain a scientifically pure world of Amateur Seismology. gmv ----- Original Message ----- From: "J�n Fr�mann" To: "PSN-Postlist" Sent: Friday, January 20, 2006 2:59 PM Subject: Noise that my geophone picks up __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise that my geophone picks up From: ian ian@........... Date: Sat, 21 Jan 2006 09:19:51 +0000 Hi, is there a wall that you could sit the geophone on top of? The wall might be sitting on the underlying bedrock. This is what I did in my last house. I drilled a hole on the top of the wall and hammered the geophone spike into it ( the spike was first unscrewed from the geophone!). This worked well along with a very similar double cover and rocks that you describe. I didn't have a problem with wind and rain, just gekos and their egg planting! Cheers Ian J�n Fr�mann wrote: >Hi Chris > >The geophone is above ground, with double box on it, inside is a plastic >box and on top of that is a wood box that has isolation material, i also >have two heavy rocks on the box to prevent it from moving in bad >weather. It is well sealed from the weather (as well it can be done). >Digging a hole 1m deep is not an option for me, becose my lawn is shared >and the there is a bedrock problay about 1m deep down, also the ground >freezing line is about 1m deep. > >The noise pickup is diffrent, i see more wind but fewer spikes that >start a warning in winsdr. Only the higest noise inside the block is now >picked up in such way it starts a warning in winsdr (like when someone >closes a door). Unlike before when i did pickup almost everything. It >also seems when the weather is good, and there is no or little traffic >the noise level go down to almost nothing (that seems to be the case at >the moment). The only thing that creates alot of spikes is when the snow >is cleared off the roads near me. But only when it is done close to my >location, less then 500m away from me. > >So far the geophone has withstand a heat change from -5C to 3C in the >past 24 hours. > >I can send a picture of my setup, if you are intrested in seeing it. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise that my geophone picks up From: "David Saum" DSaum@............ Date: Sat, 21 Jan 2006 10:23:48 -0500 (EST) Hi J�n I have a similar noise problem with my 4.5 hz geophone system that is resting on my basement office slab about 20m from a major highway. I am using Amaseis freeware for data logging and display, and I generally set the helicorder display low-pass filter to 1 Hz, and that gets rid of a lot of the local noise. When I receive and email notice of a teleseismic event, I look at the data segment even if it does not show up on my helicorder display. Often I can FFT the data segment, see the quake spectral peak, and apply a bandpass filter to bring the quake out. One test to see if your electronics is working well is to see if you can pick up the ~0.2 Hz microseism peak on your geophone system. My system can generally pick this up since I started using an AD8626 autozero opamp, a pcb with star ground configuration, and a shielded enclosure for my electronics and geophone. Ciao, Dave http://www.infiltec.com/seismo __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: winsdr auto start From: Barry Lotz barry_lotz@............. Date: Mon, 23 Jan 2006 16:55:59 -0800 (PST) Hi all I'm not that versed with windows inner workings. I was using SDR (DOS) currently. I was interested in using WINSDR but was concerned about it's starting. My power goes out a few times per year. I want to have WINSDR start automaticly when the computer comes back . Larry suggested I put WINSDR in my start up file list. I tried that but when I turn the computer off and on the program is not up and runninjg ( at lease I think). When the computer comes on, I have to log onto windows networking, then I get my desktop display. I'm not sure what is actually running. Should I see WINSDR in the maximized form or minimized? Regards Barry
Hi all

I'm not that versed with windows inner workings. I was using SDR (DOS) currently. I was interested in using WINSDR but was concerned about it's starting. My power goes out a few times per year. I want to have WINSDR start automaticly when the computer comes back . Larry suggested I put WINSDR in my start up file list. I tried that but when I turn the computer off and on the program is not up and runninjg ( at lease I think). When the computer comes on, I have to log onto windows networking, then I get my desktop display. I'm not sure what is actually running. Should I see WINSDR in the maximized form or minimized?

Regards

Barry
Subject: Re: Noise that my geophone picks up From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 24 Jan 2006 02:11:57 +0000 Hi Geoff and others. I am not the Freeman of the game Half Life, hoever few guys in my old school did call me that becose they did figure that i did look like that game caracter. :-) The problem with earthquakes here in Iceland is this, they are mostly in the range of 2 - 60Hz and problay higer. Since many of them are of volcanic nature. I am directly above bedrock, it is about 1 to 2 meters at the most down to it. Bye -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: winsdr auto start From: apsn apsn@........... Date: Mon, 23 Jan 2006 18:22:54 -0900 Barry, What I do is disable the need for an administrator name and password thus bypassing the login prompt upon startup. In Windows 2000, you can find it under Start, Control Panel, Users and Passwords, and ensure that the checkbox for "Users must enter a user name and password to use this computer" is unchecked. Realize, of course, that doing this means your PC is wide open to everyone who has physical access to it. Also, make sure the screen saver is not password protected as it also interfered with proper operation. With these changes, I got WinSDR (in the startup list) working. And it runs maximized upon cold boot up. This is the only way I found to get WinSDR to run upon cold boot in Windows 2000. If there are other ways, I'd like to hear them. Good luck, Bob http://apsn.awcable.com At 03:55 PM 1/23/2006, you wrote: >Hi all > I'm not that versed with windows inner workings. I was using SDR > (DOS) currently. I was interested in using WINSDR but was concerned > about it's starting. My power goes out a few times per year. I want > to have WINSDR start automaticly when the computer comes back . > Larry suggested I put WINSDR in my start up file list. I tried that > but when I turn the computer off and on the program is not up and > runninjg ( at lease I think). When the computer comes on, I have > to log onto windows networking, then I get my desktop display. I'm > not sure what is actually running. Should I see WINSDR in the > maximized form or minimized? >Regards >Barry __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: winsdr auto start From: Barry Lotz barry_lotz@............. Date: Mon, 23 Jan 2006 21:37:52 -0800 (PST) Bob I'm using windows 98. It has a little different setup in the control panel. The password and users are in separate locations. It seems that what I need to disable is the network password prompt. Regards Barry apsn wrote: Barry, What I do is disable the need for an administrator name and password thus bypassing the login prompt upon startup. In Windows 2000, you can find it under Start, Control Panel, Users and Passwords, and ensure that the checkbox for "Users must enter a user name and password to use this computer" is unchecked. Realize, of course, that doing this means your PC is wide open to everyone who has physical access to it. Also, make sure the screen saver is not password protected as it also interfered with proper operation. With these changes, I got WinSDR (in the startup list) working. And it runs maximized upon cold boot up. This is the only way I found to get WinSDR to run upon cold boot in Windows 2000. If there are other ways, I'd like to hear them. Good luck, Bob http://apsn.awcable.com
Bob

I'm using windows 98. It has a little different setup in the control panel. The password and users are in separate locations. It seems that what I need to disable is the network password prompt.

Regards

Barry

apsn <apsn@...........> wrote:

Barry,

What I do is disable the need for an administrator name and password
thus bypassing the login prompt upon startup.
In Windows 2000, you can find it under Start, Control Panel, Users
and Passwords, and ensure that the checkbox for "Users must enter a
user name and password to use this computer" is unchecked. Realize,
of course, that doing this means your PC is wide open to everyone who
has physical access to it. Also, make sure the screen saver is not
password protected as it also interfered with proper operation.

With these changes, I got WinSDR (in the startup list) working. And
it runs maximized upon cold boot up.

This is the only way I found to get WinSDR to run upon cold boot in
Windows 2000. If there are other ways, I'd like to hear them.

Good luck,

Bob
http://apsn.awcable.com

Subject: Re: Noise that my geophone picks up From: Kevin McCue asc@............... Date: Tue, 24 Jan 2006 21:28:53 +1100 Jon I have been enjoying this exchange of information. The frequency range of local earthquakes in Iceland is typical of the=20 frequency range of small earthquakes recorded on rock near to the=20 source. You just have to sample at a high rate 100 or preferably 200s/s=20= to see it. For monitoring of mining rock bursts up close you have to=20 increase this rate by a factor of 10 or more. In the Lachlan Foldbelt in southeastern Australia we typically record=20 ground shaking near 50 Hz for small earthquakes up to ML 4 and there=20 isn't a recently active volcano for 500 km or so. Regards Kevin On 24/01/2006, at 1:11 PM, J=F3n Fr=EDmann wrote: > Hi Geoff and others. > > I am not the Freeman of the game Half Life, hoever few guys in my old > school did call me that becose they did figure that i did look like=20 > that > game caracter. :-) > > The problem with earthquakes here in Iceland is this, they are mostly=20= > in > the range of 2 - 60Hz and problay higer. Since many of them are of > volcanic nature. > > I am directly above bedrock, it is about 1 to 2 meters at the most = down > to it. > > Bye > --=20 > J=F3n Fr=EDmann J=F3nsson > http://www.jonfr.com > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > Kevin McCue Director Australian Seismological Centre PO Box 324 Jamison Centre ACT 2614 Australia ph: 61 (0)2 6251 1291 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re[2]: winsdr auto start From: Angel sismos@.............. Date: Tue, 24 Jan 2006 12:23:49 +0000 Hello Barry, You can try to run WinSDR as a service and give it permission to interact with the desktop. Microsoft makes a tool that works sometimes to make programs run a service. I think it is call "srvany" I have used it successfully with Seislog and other programs that needed to run before user credential were entered. In the end I would get away from W98. Angel Tuesday, January 24, 2006, 5:37:52 AM, you wrote: > Bob > �I'm using windows 98. It has a little different setup in the > control panel. The password and users are in separate locations. It > seems that what I need to disable is the network password prompt. > Regards > Barry > apsn wrote: > Barry, > What I do is disable the need for an administrator name and password > thus bypassing the login prompt upon startup. > In Windows 2000, you can find it under Start, Control Panel, Users > and Passwords, and ensure that the checkbox for "Users must enter a > user name and password to use this computer" is unchecked. Realize, > of course, that doing this means your PC is wide open to everyone who > has physical access to it. Also, make sure the screen saver is not > password protected as it also interfered with proper operation. > With these changes, I got WinSDR (in the startup list) working. And > it runs maximized upon cold boot up. > This is the only way I found to get WinSDR to run upon cold boot in > Windows 2000. If there are other ways, I'd like to hear them. > Good luck, > Bob > http://apsn.awcable.com -- Best regards, Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise that my geophone picks up From: ChrisAtUpw@....... Date: Tue, 24 Jan 2006 07:48:15 EST In a message dated 24/01/2006, asc@............... writes: Jon I have been enjoying this exchange of information. The frequency range of local earthquakes in Iceland is typical of the frequency range of small earthquakes recorded on rock near to the source. You just have to sample at a high rate 100 or preferably 200s/s to see it. For monitoring of mining rock bursts up close you have to increase this rate by a factor of 10 or more. In the Lachlan Foldbelt in south-eastern Australia we typically record ground shaking near 50 Hz for small earthquakes up to ML 4 and there isn't a recently active volcano for 500 km or so. Regards Kevin Hi Jon, Kevin, Jon is using one of Larrys's four channel amplifier boards. These have a nominal bandwidth of 20 sec to 10 Hz, with an 8 pole Butterworth roll off. It is 20 dB down by 20 Hz and 40 dB down by 30 Hz. I doubt if there is any point in sampling beyond 50 sps, and 30 sps would probably would be satisfactory. See _http://psn.quake.net/serialamp.html_ (http://psn.quake.net/serialamp.html) Jon also has sea noise and local environmental noise to cope with. Your comments, please, Kevin? Regards, Chris Chapman

In a message dated 24/01/2006, asc@............... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Jon
I=20 have been enjoying this exchange of information. The frequency range of lo= cal=20 earthquakes in Iceland is typical of the frequency range of small earthqua= kes=20 recorded on rock near to the source. You just have to sample at a high rat= e=20 100 or preferably 200s/s to see it. For monitoring of mining rock bursts u= p=20 close you have to increase this rate by a factor of 10 or more.
In the=20 Lachlan Foldbelt in south-eastern Australia we typically record ground sha= king=20 near 50 Hz for small earthquakes up to ML 4 and there isn't a recently act= ive=20 volcano for 500 km or so.
Regards
Kevin

Hi Jon, Kevin,

    Jon is using one of Larrys's four channel ampli= fier=20 boards. These have a nominal bandwidth of 20 sec to 10 Hz, with an 8 pole=20 Butterworth roll off. It is 20 dB down by 20 Hz and 40 dB down by 30 Hz. I d= oubt=20 if there is any point in sampling beyond 50 sps, and 30 sps would proba= bly=20 would be satisfactory. See http://psn.quake.net/serialamp.= html

    Jon also has sea noise and local environmental=20 noise to cope with.

    Your comments, please, Kevin?

    Regards,

    Chris Chapman
Subject: from Angel From: Angel sismos@.............. Date: Tue, 24 Jan 2006 13:24:09 +0000 Hi Larry, Please give me a price on an 8 channel serial ADC with two amp boards with mounting kit with cables. In a box if you have one. I want to take 8 VHF/UHF telemetry channels and take them to and Earthworm system. I am assuming that I need to amplify these channels after the demodualtor. I have not used telemetry station before. It would be shipped to Seattle and needs to be there by Feb. 2nd. Regards, angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: from Angel From: Angel sismos@.............. Date: Tue, 24 Jan 2006 14:18:31 +0000 Larry, please add a GPS to the last quote. 1 serial board 2 four channel amp boards mounting kit gps all in a box if possible with longest GPS cable you can provide. angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: My apologies to the list From: Angel sismos@.............. Date: Tue, 24 Jan 2006 14:39:57 +0000 Sorry to everyone, Those last two messages were meant privately for Larry. I have sworn before not to use reply on this list. :( Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Windows auto start From: "Thomas Dick" dickthomas01@............. Date: Tue, 24 Jan 2006 11:05:05 -0600 I used it on Windows 98. Now using it on Windows 2000. I had to wait for my techie son to put it in simple terms but here it is 1.one solution TweakUI, a widely available program forWindows, has this feature built-in, for automatically signing on. 2.second solution If one is brave enough to take on registry editting, then you Start-Run->Regedit 3. third solution and the one I resorted to ... Goto: Local Machine->Software->Microsoft->Windows NT->Current Version->Winlogon In this part of the tree, new or existing string keys need to be set thusly: Key: Values: AutoAdminLogon 1 DefaultUserName WhateverYourSignonNameGoesHere DefaultPassword YourPasswordAtStartupGoesHere DefaultDomainName NameOfYourComputerHere DisableCAD 1 You can find out the name of your computer from the "Computer Name" tab of the System control panel. Watch out! Twice I lost data because the hard drive ran out of memory. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: tornadoes and earthquake detection From: "Thomas Dick" dickthomas01@............. Date: Wed, 25 Jan 2006 14:03:27 -0600 Geoff, where did you get these figures you made on the net on this date? Sent: Friday, December 02, 2005 2:47 PM Subject: Re: tornadoes and earthquake detection > > You should do a FFT analysis of your raw digital > data and see if you can extract the rotational rate of the funnel cloud > from the data. > I would expect the rotational rate of a .75 mile > wide funnel with 100 mph wind speed to have > a rotational period near 84 seconds or less. > > If the tornado was traveling at 60mph > then the rotational speed was probably > only about 100mph. > > It made me sad that was unable to see the > seismic data, but what the hey, thats the story of my life. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fault zones in Iceland From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 26 Jan 2006 05:54:24 +0000 Hi all Here is a map that shows the fault zones and the hotspot of Iceland, if my loaction is marked on that map it is clear that i hopefully will be able to detect earthquakes that are <2.5 on the ricther scale. I am close to most of the fault zones here in Iceland, but not too close. http://home1.gte.net/res04as8/Grimsvtn/map.html I am also near (less then 20 km) a old rupture zone that was active at least 3,3 million years ago. But i do now know if earthquakes happens there at all or some other type of activti (it looks pretty dead). I have seen earthquakes that are less then 40 km away from where i life (south of me, but in both cases the trigger was activiti near Hverav�llum with earthquakes from 1 - 3.5 mag), but they where small, around 1,5 - 2,8 on the ricther scale (minimal that Icelandic met Office detects at that range, based on the location of there stations). There have been large earthquakes near where i life, the last one was in 1973 and was 5,5 on the ricther scale (South-West of me). The largest one mesured was a mag 7 on the ricther scale in 1963 and was about 60 - 80 km where i life (North-East of where i life). I fear that when there is going to me a earthquake above 6 on the ricther scale that my geophone will move in the tremor (like get displaced from it's location). However a earthquake at that size and that close to me is unlikley, but not impossible. But both of those earthquakes did happen before i was born and i did miss the big earthquakes (two 6,5 mag) in the year 2000 that did happen in south of Iceland. I also have one question to ask this time. Does anyone know how the ocen wave appears on seismograph ? Becose i was doing some work on my geophone early this night and after that i see wave top appear on my seismographs (preventing the geophone from moving by increase the pressure on him with plastic bags inside of the box that is on top of him, also to minimize the wind noise as i can), those tops are "smooth" and don't look like wind noise. I doubt that this is the plastic bags fault. There appars to be increased activiti at Hverav�llum. Two earthquakes recored by the Iceland met Office in past 24 hours or so. Thanks. Bye. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Fault zones in Iceland From: ChrisAtUpw@....... Date: Thu, 26 Jan 2006 09:30:13 EST In a message dated 26/01/2006, jonfr500@......... writes: I also have one question to ask this time. Does anyone know how the ocean wave appears on seismograph? Because I was doing some work on my geophone early this night and after that I saw wave top appear on my seismographs (preventing the geophone from moving by increase the pressure on him with plastic bags inside of the box that is on top of him, also to minimise the wind noise as I can), those tops are "smooth" and don't look like wind noise. I doubt that this is the plastic bags fault. Hi Jon, The Atlantic ocean microseisms may be 0.5 to 15 microns with a period of 6 to 7 seconds. I very much doubt if your geophones will see this. The waves are usually short sections of rather rough sine form. Since you are fairly close to the sea, you may pick up wave noise. You are likely to see storm noise. If you have any air filled plastic bags in your seismometer box, I suggest that you remove them immediatly. They are likely to react quite strongly both to changes in atmospheric pressure and to wind speed! The accelerations that you normally observe should not move a geophone case set on the ground. If you want to provide a more firm fixing, I suggest that you get some children's 'plasticene' (like a non sticky putty) and use this to 'join' the geophone case to the concrete. See _http://www.bostik.com.au/pdf/datasheet/bostik_blu_tack.pdf_ (http://www.bostik.com.au/pdf/datasheet/bostik_blu_tack.pdf) I can buy Blu-Tack and White-Tack adhesive putty from stationers. It is now available in the US. See _http://www.artech-electronics.com/us/products/accesso/blutack.html_ (http://www.artech-electronics.com/us/products/accesso/blutack.html) It is a semi elastic non drying adhesive mastic which hardens over a period of weeks, but may be kneaded again by hand and re-used. Very useful for making demountable seals, sticking posters to walls without damaging the finish etc.. Regards, Chris Chapman

In a message dated 26/01/2006, jonfr500@......... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I also=20 have one question to ask this time. Does anyone know how the ocean
wave= =20 appears on seismograph? Because I was doing some work on my
geophone ea= rly=20 this night and after that I saw wave top appear on my
seismographs= =20 (preventing the geophone from moving by increase the
pressure on him wi= th=20 plastic bags inside of the box that is on top of
him, also to minimise=20= the=20 wind noise as I can), those tops are "smooth"
and don't look like=20= wind=20 noise. I doubt that this is the plastic=20 bags
fault.

Hi Jon,

    The Atlantic ocean microseisms may be 0.5 to 15= =20 microns with a period of 6 to 7 seconds. I very much doubt if your geophones= =20 will see this. The waves are usually short sections of rather rough sine for= m.=20 Since you are fairly close to the sea, you may pick up wave noise. You are=20 likely to see storm noise.

    If you have any air filled plastic bags in your= =20 seismometer box, I suggest that you remove them immediatly. They are li= kely=20 to react quite strongly both to changes in atmospheric pressure an= d to=20 wind speed!

    The accelerations that you normally observe sho= uld=20 not move a geophone case set on the ground. If you want to provide a more fi= rm=20 fixing, I suggest that you get some children's 'plasticene' (like a non stic= ky=20 putty) and use this to 'join' the geophone case to=20 the concrete.

    See http://w= ww.bostik.com.au/pdf/datasheet/bostik_blu_tack.pdf I=20 can buy Blu-Tack and White-Tack adhesive putty from stationers. It is now=20 available in the US. See

= http://www.artech-electronics.com/us/products/accesso/blutack.html = It=20 is a semi elastic non drying adhesive mastic which hardens over a period of=20 weeks, but may be kneaded again by hand and re-used. Very useful for making=20 demountable seals, sticking posters to walls without damaging the finish=20 etc..

    Regards,

    Chris Chapman
Subject: ebay auction From: Bob Barns royb1@........... Date: Thu, 26 Jan 2006 10:00:52 -0500 Hi gang, Seismograph Earthquake Vibration Seismic Geophone Kit Item number: 7585030314 ends 2/1 Might be a way to introduce kids to seismology. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Fault zones in Iceland From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 26 Jan 2006 21:25:58 +0000 Hi all I did remove the plastic bags as Chris Chapman did advice me, but i did also move my geophone back inside. Becose the noise inside the house is less then the noise that is outside and the house also tamper the wind noise down alot. I have been wondering about lowpassfilter and higpassfilter, i do know where i can detect the earthquakes. But that is from 2Hz to 10Hz that can work for me. But i don't know if they lowpassfreq cutoff is 2Hz or 4Hz and other way around regarding the higpassfreq cutoff. I have been reading help for winsdr regarding that, but i don't understand what is what. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Fault zones in Iceland From: ChrisAtUpw@....... Date: Thu, 26 Jan 2006 21:38:56 EST In a message dated 26/01/2006, jonfr500@......... writes: I have been wondering about low pass filter and high pass filter, I do know where I can detect the earthquakes. But that is from 2Hz to 10Hz that can work for me. But I don't know if they low pass freq cut-off is 2Hz or 4Hz and other way around regarding the high pass freq. cut-off. I have been reading help for winsdr regarding that, but I don't understand what is what. Hi Jon, A low pass filter is one which passes all frequencies up to about the cut-off frequency without loss. The amplitude of any signal above the cut-off frequency drops very quickly and it is depends on the number of 'poles' or filter sections. A high pass filter passes frequencies above the cut-off frequency. The low pass filter on your amplifier board should be 10 Hz and have 8 poles. In practice, a signal at 13.4 Hz will be reduced to 1/10 and one at 18 Hz to 1/100. The amplifier has a high pass filter set at 0.05 Hz = 20 sec., which is well below the lowest response of your geophones. The low frequency response is set by the geophone, 4.5 Hz in this case. From 4.5 to 60 Hz, the response is nearly constant. Below 4.5 Hz the response falls off roughly proportional to the square of the frequency ratio. So a 2 Hz signal can give ~1/5 the amplitude, but you may still see it. A 1 Hz signal will only give ~1/20 the amplitude and this is likely to be lost in the noise. A 0.5 Hz signal will give ~1/100 the amplitude. So, putting this signal into your system, you will see a flat response between 4.5 an 10 Hz. The response falls very quickly for signals above 10 Hz, but much less quickly for signals below 4.5 Hz. The local quakes which you are likely to observe have a lot of higher frequency components, certainly to 10 Hz and maybe to over 40 Hz, which is good for your system. Unfortunately the environmental noise also increases with frequency in this range, which will limit your ability to detect the quakes. Choosing the quietest place for your geophones is important. This is best done by taking several 24 hr recordings, observing the weather and wind strength and estimating how the noise signal changes with time. There are likely to be higher noise levels when residents leave for work in the morning and return in the evening. Snow clearance vehicles and heavy lorries can make quite a noise. The wind noise is likely to increase with the square of the wind speed. Buildings are shaken by the wind and the vibrations are coupled into the ground nearby. Placing the geophone on a basement floor, but away from the outside walls may help. Hope that this is of help. Please say if there is anything you don't understand. Chris Chapman

In a message dated 26/01/2006, jonfr500@......... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I have=20 been wondering about low pass filter and
high pass filter, I do kn= ow=20 where I can detect the earthquakes. But that is
from 2Hz to 10Hz t= hat=20 can work for me. But I don't know if they
low pass freq cut-off is= 2Hz=20 or 4Hz and other way around regarding the
high pass freq. cut-off. I ha= ve=20 been reading help for winsdr regarding that,
but I don't understan= d=20 what is what.

Hi Jon,

    A low pass filter is one which passes all=20 frequencies up to about the cut-off frequency without loss. The amplitude of= any=20 signal above the cut-off frequency drops very quickly and it is depends=20 on the number of 'poles' or filter sections.

    A high pass filter passes frequencies above the= =20 cut-off frequency.

    The low pass filter on your amplifier board sho= uld=20 be 10 Hz and have 8 poles. In practice, a signal at 13.4 Hz will be reduced=20= to=20 1/10 and one at 18 Hz to 1/100.

    The amplifier has a high pass filter set at 0.0= 5 Hz=20 =3D 20 sec., which is well below the lowest response of your geophones.

    The low frequency response is set by the=20 geophone, 4.5 Hz in this case. From 4.5 to 60 Hz, the response is=20 nearly constant. Below 4.5 Hz the response falls off roughly proportional to= the=20 square of the frequency ratio. So a 2 Hz signal can give ~1/5= the=20 amplitude, but you may still see it. A 1 Hz signal will only give ~1/20= the=20 amplitude and this is likely to be lost in the noise. A 0.5 H= z=20 signal will give ~1/100 the amplitude.

    So, putting this signal into your system,=20 you will see a flat response between 4.5 an 10 Hz. The response fa= lls=20 very quickly for signals above 10 Hz, but much less quickly for signals= =20 below 4.5 Hz.

    The local quakes which you are likely to observ= e=20 have a lot of higher frequency components, certainly to 10 Hz and maybe= to=20 over 40 Hz, which is good for your system. Unfortunately the environmental n= oise=20 also increases with frequency in this range, which will limit your=20 ability to detect the quakes. Choosing the quietest place for your=20 geophones is important. This is best done by taking several 24 hr=20 recordings, observing the weather and wind strength and estimating how the n= oise=20 signal changes with time. There are likely to be higher noise levels when=20 residents leave for work in the morning and return in the evening. Snow=20 clearance vehicles and heavy lorries can make quite a noise. The wind noise=20= is=20 likely to increase with the square of the wind speed. Buildings are shaken b= y=20 the wind and the vibrations are coupled into the ground nearby. Placing the=20 geophone on a basement floor, but away from the outside walls may=20 help.

    Hope that this is of help. Please say if there=20= is=20 anything you don't understand.

    Chris Chapman

Subject: Re: Fault zones in Iceland From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 27 Jan 2006 03:00:08 +0000 Hi Chris Thanks for the info. I did set the low pass cutoff freq to 4.5Hz (i might have turned that setting off when you read this email, just to compare the resaults), since most of the noise is above that level as you say. But i wonder if i am right on doing that. The noise level is alot less sinice i did move my geophone back in, execpt from the noise from me and strong wind that was going on to night. It has been rather flat line. I will need a earthquake to see if my low pass cutoff settings are correct or not. I still detect the noise from my movements, but at they are alot more lower then before. I am looking into moving the geophone into my storage room, it can be done. But not until i get a specal computer for it. Since i can't draw a wire from that location and into my apartment. I will have to use wlan and two winsdr to do this. Connected together over the wlan. If that can be done to start with. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: exact frequencies for arrival of different seismic waves ?? From: "Geoff" gmvoeth@........... Date: Thu, 26 Jan 2006 20:29:31 -0700 Hello; Can anyone tell me ? Are there exact frequencies for the first arrival time of P and S waves ? I have only seen ranges of frequencies. If I could pin down exact frequencies I could make a summation of maybe three narrow band pass filters with a relatively high Q to look for each of these waves. I suspect the ground may behave in a predictable fashion with the leading edge of a wave train. Has anyone ever researched this in any depth with test equipment that can show reality ? I know for a fact that the government has incredible test equipment because I have seen some of it but not that which is designed for geological work. I have seen charts showing ranges of freqs but here I am only interested in exact frequencies or slew rates of the first time of arrival and not the train that follows. also; If you are looking for seismic waves created by nuclear explosions, what would you be looking for ? gmv __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: exact frequencies for arrival of different seismic waves ?? From: Dave Nelson davenn@............... Date: Fri, 27 Jan 2006 15:30:47 +1100 Hi Geoff there are NO exact frequencies ... the frequency of the different waves arriving at the sensor are dependant on many factors. 1) type and depth of rupture 2) distance between the sensor and the rupture 3) sensor location relative to the ruprture to name a few take 2) .. distance between your sensor and the rupture..... as distance increases you loose the higher freq component of the signal because of attenuation/absorption just as you do with sound waves over distance eg. think of a rumble of thunder in a storm .... if you are close to the lightning strike you hear the sharp crack of the thunder as distance increases you only get to hear the low freq rumblings or another pratical example .... think of that loud music being played by your noisy neighbour what do you hear ?? ... the thump thump of the bass and drums the hi freq has all but gone ( they are all there at the source!) when refering to sensor location I am referring to compass bearing to the rupture from the sensor ( or visa versa) eg on a strike slip fault ... if you are in the compressional quadrant of the outgoing waves you are likely to see a far different waveform than if you are in the dilation quadrant. see my brief discussion of this on my www page ...... http://www.sydneystormcity.com/fomec.htm if you look at diag B you can see the 4 quadrants 2 compressional and 2 dilational and the sensor location within those quadrants will have a determination on the amplitude and freq of the received waveform this all applies to teleseisms as well .... note how they lack much in the way of P and S wave signal MOST of it is the lower freq surface waves basically then, the closer the quake, the more hi freq component your sensor will detect hence why professional stations use broadband sensors ... record EVERYTHING, then filter accordingly to retrieve the wanted data cheers Dave N Sydney Australia At 20:29 26/01/2006 -0700, you wrote: >Hello; >Can anyone tell me ? >Are there exact frequencies for the first >arrival time of P and S waves ? >I have only seen ranges of frequencies. >If I could pin down exact frequencies I could >make a summation of maybe three narrow band pass >filters with a relatively high Q to look for >each of these waves. > >I suspect the ground may behave in a >predictable fashion with the leading edge >of a wave train. >Has anyone ever researched this in any depth >with test equipment that can show reality ? >I know for a fact that the government has >incredible test equipment because I have seen >some of it but not that which is designed >for geological work. >I have seen charts showing ranges of freqs >but here I am only interested in exact >frequencies or slew rates of the first >time of arrival and not the train that follows. > >also; >If you are looking for seismic waves >created by nuclear explosions, what >would you be looking for ? > >gmv __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: exact frequencies for arrival of different seismic waves ?? From: "Geoff" gmvoeth@........... Date: Thu, 26 Jan 2006 23:34:45 -0700 Thanks Dave; I just got three EQs from Baja California looks like two foreshocks and the main, they are a little over three degrees away and 4,0 or less in magnitude. It looks to me like the P waves are in the hertz range which is beyond the rolloff of my current filter. The other day I received Teleseismic event from New Zealand that was said to be 90deg away and only 5.2 mag which was inband..it looked like the freq was down around 5 hertz or so. You pointd out something I never saw before with the link you provided, thank you very much. I never understood what those spheres represented till now. I am currently using a two octave filter which provides flatness below 1 Hz and am able to see both regional and teleseismic P waves. My filter is down to three opamps now where it used to be 8 or so :-) and I get better results. I got this penpal over in England that believes in a KISS philosophy (Keep it Simple Stupid) that philosophy has proven to be true. Once Again Thanks to PSN and people like yourself I am an old dog learning new tricks. gmv ----- Original Message ----- From: "Dave Nelson" To: Sent: Thursday, January 26, 2006 9:30 PM Subject: Re: exact frequencies for arrival of different seismic waves ?? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Intrest in Volcano activiti ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 27 Jan 2006 22:54:37 +0000 Hi all I am wondering if anyone that is on the psn postlist has intrest in volcano activiti. But that is my main intrest along with earthquakes. Greetings. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Fault zones in Iceland From: Larry Cochrane lcochrane@.............. Date: Fri, 27 Jan 2006 18:14:21 -0800 Hi Everyone, Chris wrote: > The low pass filter on your amplifier board should be 10 Hz and have 8 > poles. In practice, a signal at 13.4 Hz will be reduced to 1/10 and one at 18 > Hz to 1/100. > The amplifier has a high pass filter set at 0.05 Hz = 20 sec., which is > well below the lowest response of your geophones. Actually Jon's Amp/Filter board has a 20 Hz 7 pole low pass filter. I usually set the filter to 20 Hz instead of the 10 Hz if I know that the filter board will be used with a geophone to record local events. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Fault zones in Iceland From: Tamati chief.cook.nz@............ Date: Sun, 29 Jan 2006 04:40:58 +1300 TAMATI's WORD's OF WISDOM FOR THE GOOD OF ALL MANKIND HTTP://LIVE-PLANET.BLOGSPOT.COM http://www.webspawner.com/users/chiefcooknz/index.html Please give me feed back on what you think chief.cook.nz.@............ NZ-021-150-33-59 or NZ-07-855-0195 Good Morning from NZ (2-53am) Can you send my a circut diagram and a Pic of the Amplifer please I've = thought of a way of making pickup 1/ A plastic Jam jar with a screw lid full of jelly or grease or fat or = sand or even sugar with the screw lid screwed down tight 2/ take an old computer case with the speaker still mount in it 3/ Run a couple of long wires from the speaker in inside comuputer case = outside the cas (I have about 5 or 6 of them) =20 4/ Put he comuter case inside a trash bag with the wires from the = speaker outside the trash bag and then seal it with packing tape 5/ dig a hole in the ground about a metre deep and bury the computer = case=20 6/ The speaker would act as Microphone to your ampilfier (perampifier)=20 7/ Run the wires to the microphone jack on my computer or a laptop use a = software music mixer/editor prg with shows the music as waves 8/ Then PRINT IT or export inputed data to a file compatable with a prg = that would show the wave and PRINT IT What do you think of my idea as I'm a Member of:-=20 "THE NUMBER 8 WIRE KIWI CLUB" (Inventor) Cheers Tamati From the Castle of Tamati, Hinemoa and Karauwa the Dog From the Castle of Tom, Robyn and the Dog I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195 Bush Telegragh:- = chief.cook.nz@............ My Regular Pitstop:- Tamati P.O.BOX 19-356 CENTRAL HAMILTON NEW = ZEALAND ----- Original Message -----=20 From: "Larry Cochrane" To: Sent: Saturday, January 28, 2006 3:14 PM Subject: Re: Fault zones in Iceland > Hi Everyone, >=20 > Chris wrote: >> The low pass filter on your amplifier board should be 10 Hz and have = 8=20 >> poles. In practice, a signal at 13.4 Hz will be reduced to 1/10 and = one at 18=20 >> Hz to 1/100. >> The amplifier has a high pass filter set at 0.05 Hz =3D 20 sec., = which is=20 >> well below the lowest response of your geophones. >=20 > Actually Jon's Amp/Filter board has a 20 Hz 7 pole low pass filter. I = usually set the=20 > filter to 20 Hz instead of the 10 Hz if I know that the filter board = will be used=20 > with a geophone to record local events. >=20 > Regards, > Larry Cochrane > Redwood City, PSN >=20 > __________________________________________________________ >=20 > Public Seismic Network Mailing List (PSN-L) >=20 > To leave this list email PSN-L-REQUEST@.............. with=20 > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information.

TAMATI's WORD's OF = WISDOM
FOR=20 THE GOOD OF ALL MANKIND
HTTP://LIVE-PLANET.BLOGSPOT.COM
<= FONT=20 face=3DGeorgia>http://www.webspawner.com/users/chiefcooknz/index.html
Please give me feed back on what you = think
chief.cook.nz.@............
NZ-021-150-33-59 or NZ-07-855-0195

Good Morning from NZ (2-53am)

Can you send my a circut = diagram and=20 a Pic of the Amplifer please I've thought of a way of making=20 pickup

1/ A plastic Jam = jar with a=20 screw lid full of jelly or grease or fat or sand or even sugar with the = screw=20 lid screwed down tight

2/ take an old computer = case with the=20 speaker still mount = in=20 it

3/=20 Run a couple = of long=20 wires from the speaker in inside comuputer case outside the cas (I = have=20 about 5 or 6 of them)

4/ Put he comuter case = inside a trash=20 bag with the wires from the speaker outside the trash bag and then seal = it with=20 packing tape

5/ dig a hole in the = ground about a=20 metre deep and bury the computer case

6/ The=20 speaker would act as Microphone = to your=20 ampilfier (perampifier)

7/ Run the wires to the microphone jack on my computer = or a=20 laptop use a software music mixer/editor prg with shows the = music as=20 waves

8/ Then PRINT IT = or export=20 inputed data to a file compatable with a prg that would show the wave = and PRINT=20 IT

What do you think of my = idea as I'm a=20 Member of:-

"THE NUMBER 8 WIRE KIWI = CLUB"=20 (Inventor)

Cheers Tamati
From the = Castle of=20 Tamati, Hinemoa and Karauwa the Dog
From the Castle of Tom, Robyn and = the=20 Dog

I'm Just a Stone's Throw Away:- = NZ-021-150-33-59=20 or=20 NZ-07-855-0195
         &= nbsp;           &n= bsp;       =20 Bush Telegragh:- chief.cook.nz@............
=          =20             &= nbsp;      =20 My Regular Pitstop:- Tamati
           &nbs= p;            = ;     =20 P.O.BOX 19-356=20 CENTRAL
          &n= bsp;           &nb= sp;           &nbs= p;            = ;            =     =20 HAMILTON
          &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;     =20 NEW ZEALAND

----- Original Message ----- =

From: "Larry Cochrane" = <lcochrane@..............>

To: <psn-l@..............>

Sent: Saturday, January 28, 2006 3:14=20 PM

Subject: Re: Fault zones in=20 Iceland

> Hi Everyone,
>
> Chris = wrote:
>> The low=20 pass filter on your amplifier board should be 10 Hz and have 8=20
>> poles. In practice, a signal at 13.4 Hz will be reduced = to =20 1/10 and one at 18
>> Hz to = 1/100.
>> =20 The amplifier has a high pass filter set at 0.05 Hz =3D 20 sec., = which is=20
>> well below the lowest response of your geophones.
> =
>=20 Actually Jon's Amp/Filter board has a 20 Hz 7 pole low pass filter. I = usually=20 set the
> filter to 20 Hz instead of the 10 Hz if I know that the = filter=20 board will be used
> with a geophone to record local = events.
>=20
> Regards,
> Larry Cochrane
> Redwood City, = PSN
>=20
> = __________________________________________________________
>=20
> Public Seismic Network Mailing List (PSN-L)
>
> To = leave=20 this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): = unsubscribe
> See http://www.seismicnet.com/maillist.html for more information. Subject: force gauge/transducer From: Jan Froom JDarwin@............. Date: Mon, 30 Jan 2006 12:12:21 -0800 Anyone know of a simple... quick... force gauge or force transducer... 20 - 30 grams max with a resolution of .1 gram. that I could make or buy? I'm working on a wind tunnel for my grandson's science fair project and we need a way to measure the lift and drag. I can measure lift with a beam balance scale... but the drag is in a horizontal direction and because the force is so low, I hate using a pulley arrangement to change the direction from horizontal to vertical. Oh... and did I say cheap? I'd settle for a spring gauge if I could find a source... that's accurate at this low a force. Thanks.... Jan in Gilroy __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: force gauge/transducer From: "Jack Ivey" ivey@.......... Date: Mon, 30 Jan 2006 15:49:52 -0500 How about a piece of "feeler gauge" material (10 mm X 50-150 mm strip of thin springy steel), clamped at one end and hanging vertically. You may be able to get some from an auto or machine shop supply place or mcmastercarr.com. You can get a nice little tool that comprises a bunch of these strips of different thicknesses, arranged to open up like a fan. That way you could just pick the thickness that works best and take it out of the set. Jack =20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Jan Froom Sent: Monday, January 30, 2006 3:12 PM To: psn-l@.............. Subject: force gauge/transducer Anyone know of a simple... quick... force gauge or force transducer... 20 - 30 grams max with a resolution of .1 gram. that I could make or buy? I'm working on a wind tunnel for my grandson's science fair project and=20 we need a way to measure the lift and drag. I can measure lift with a beam balance scale... but the drag is in a=20 horizontal direction and because the force is so low, I hate using a=20 pulley arrangement to change the direction from horizontal to vertical. Oh... and did I say cheap? I'd settle for a spring gauge if I could find a source... that's=20 accurate at this low a force. Thanks.... Jan in Gilroy __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: force gauge/transducer From: Jan Froom JDarwin@............. Date: Mon, 30 Jan 2006 13:20:08 -0800 Thanks Jack... Had to think about it for a minute or two.... I assume you're suggesting that you then put a sheet of paper behind the strip, and then using a beam balance scale, calibrate the amount of bend and mark that on the paper. Simple and neat. Jan Jack Ivey wrote: >How about a piece of "feeler gauge" material (10 mm X 50-150 mm strip of >thin springy steel), clamped at one end and hanging vertically. You may > >be able to get some from an auto or machine shop supply place or >mcmastercarr.com. You can get a nice little tool that comprises a bunch > >of these strips of different thicknesses, arranged to open up like a >fan. That way you could just pick the thickness that works best and >take it >out of the set. > >Jack > >-----Original Message----- >From: psn-l-request@.............. [mailto:psn-l-request@............... >On Behalf Of Jan Froom >Sent: Monday, January 30, 2006 3:12 PM >To: psn-l@.............. >Subject: force gauge/transducer > >Anyone know of a simple... quick... force gauge or force transducer... >20 - 30 grams max with a resolution of .1 gram. that I could make or >buy? > >I'm working on a wind tunnel for my grandson's science fair project and >we need a way to measure the lift and drag. >I can measure lift with a beam balance scale... but the drag is in a >horizontal direction and because the force is so low, I hate using a >pulley arrangement to change the direction from horizontal to vertical. > >Oh... and did I say cheap? > >I'd settle for a spring gauge if I could find a source... that's >accurate at this low a force. > >Thanks.... Jan in Gilroy > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > > > > Thanks Jack...
Had to think about it for a minute or two....
I assume you're suggesting that you then put a sheet of paper behind the strip, and then using a beam balance scale, calibrate the amount of bend and mark that on the paper. Simple and neat.

Jan

Jack Ivey wrote:

How about a piece of "feeler gauge" material (10 mm X 50-150 mm strip of
thin springy steel), clamped at one end and hanging vertically.  You may

be able to get some from an auto or machine shop supply place or
mcmastercarr.com.  You can get a nice little tool that comprises a bunch

of these strips of different thicknesses, arranged to open up like a
fan.  That way you could just pick the thickness that works best and
take it
out of the set.

Jack  

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@..............]
On Behalf Of Jan Froom
Sent: Monday, January 30, 2006 3:12 PM
To: psn-l@..............
Subject: force gauge/transducer

Anyone know of a simple... quick... force gauge or force transducer...
20 - 30 grams max with a resolution of .1 gram.   that I could make or
buy?

I'm working on a wind tunnel for my grandson's science fair project and 
we need a way to measure the lift and drag.
I  can measure lift with a beam balance scale... but the drag is in a 
horizontal direction and because the force is so low, I hate using a 
pulley arrangement to change the direction from horizontal to vertical.

Oh... and did I say cheap?

I'd settle for a spring gauge if I could find a source... that's 
accurate at this low a force.

Thanks.... Jan in Gilroy

__________________________________________________________

Public Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@.............. with 
the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.
__________________________________________________________

Public Seismic Network Mailing List (PSN-L)

To leave this list email PSN-L-REQUEST@.............. with 
the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.

Subject: RE: force gauge/transducer From: "Jack Ivey" ivey@.......... Date: Mon, 30 Jan 2006 17:37:28 -0500 Thanks for clarifying my post, I was even more cryptic than usual. =20 Jack =20 ________________________________ From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Jan Froom Sent: Monday, January 30, 2006 4:20 PM To: psn-l@.............. Subject: Re: force gauge/transducer =20 Thanks Jack...=20 Had to think about it for a minute or two.... =20 I assume you're suggesting that you then put a sheet of paper behind the strip, and then using a beam balance scale, calibrate the amount of bend and mark that on the paper. Simple and neat. Jan Jack Ivey wrote:=20 How about a piece of "feeler gauge" material (10 mm X 50-150 mm strip of thin springy steel), clamped at one end and hanging vertically. You may =20 be able to get some from an auto or machine shop supply place or mcmastercarr.com. You can get a nice little tool that comprises a bunch =20 of these strips of different thicknesses, arranged to open up like a fan. That way you could just pick the thickness that works best and take it out of the set. =20 Jack =20 =20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Jan Froom Sent: Monday, January 30, 2006 3:12 PM To: psn-l@.............. Subject: force gauge/transducer =20 Anyone know of a simple... quick... force gauge or force transducer... 20 - 30 grams max with a resolution of .1 gram. that I could make or buy? =20 I'm working on a wind tunnel for my grandson's science fair project and=20 we need a way to measure the lift and drag. I can measure lift with a beam balance scale... but the drag is in a=20 horizontal direction and because the force is so low, I hate using a=20 pulley arrangement to change the direction from horizontal to vertical. =20 Oh... and did I say cheap? =20 I'd settle for a spring gauge if I could find a source... that's=20 accurate at this low a force. =20 Thanks.... Jan in Gilroy =20 __________________________________________________________ =20 Public Seismic Network Mailing List (PSN-L) =20 __________________________________________________________ =20 Public Seismic Network Mailing List (PSN-L) =20 =20 =20 =20 =20

Thanks for clarifying my post, I = was even more cryptic than usual.

Jack

From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Jan Froom
Sent: Monday, January 30, = 2006 4:20 PM
To: psn-l@..............
Subject: Re: force gauge/transducer

Thanks Jack...
Had to think about it for a minute or two....
I assume you're suggesting that you then put a sheet of paper behind the = strip, and then using a beam balance scale, calibrate the amount of bend and = mark that on the paper. Simple and neat.

Jan

Jack Ivey wrote:

How about a piece of "feeler gauge" =
material (10 mm X 50-150 mm strip =
of

thin springy steel), clamped at one end and =
hanging vertically.  You =
may

be able to get some from an auto or machine =
shop supply place or

mcmastercarr.com.  You can get a nice =
little tool that comprises a =
bunch

of these strips of different thicknesses, =
arranged to open up like a

fan.  That way you could just pick the =
thickness that works best and

take =
it

out of the =
set.

Jack  =

-----Original =
Message-----

From: psn-l-request@...............
 [mailto:psn-l-request@webtron=
ics.com]

On Behalf Of Jan =
Froom

Sent: Monday, January 30, 2006 3:12 =
PM

To: psn-l@..............<=
/span>

Subject: force =
gauge/transducer

Anyone know of a simple... quick... force =
gauge or force transducer...

20 - 30 grams max with a resolution of .1 =
gram.   that I could make =
or

buy?

I'm working on a wind tunnel for my =
grandson's science fair project and =

we need a way to measure the lift and =
drag.

I  can measure lift with a beam balance =
scale... but the drag is in a

horizontal direction and because the force is =
so low, I hate using a

pulley arrangement to change the direction =
from horizontal to vertical.

Oh... and did I say =
cheap?

I'd settle for a spring gauge if I could find =
a source... that's

accurate at this low a =
force.

Thanks.... Jan in Gilroy

<= pre>

______________________________________________=
____________

Public Seismic Network Mailing List =
(PSN-L)

To leave this list email PSN-L-REQUEST@...............
 with

the body of the message (first line only): =
unsubscribe

See http://www.seismicnet.co=
m/maillist.html for more =
information.

______________________________________________=
____________

Public Seismic Network Mailing List =
(PSN-L)

To leave this list email PSN-L-REQUEST@...............
 with

the body of the message (first line only): =
unsubscribe

See http://www.seismicnet.co=
m/maillist.html for more =
information.

Subject: Re: Digest from 01/30/2006 00:01:27 From: Roger Sparks rsparks@.......... Date: Tue, 31 Jan 2006 08:55:47 -0800 Hi Jan, A hacksaw blade can become a very sensitive spring. Other sources of good spring material are the recoil springs from lawn mower motors, or even smaller, the recoil spring from a tape measure. You could calibrate horizontal beam deflection with the use of weights previously measured with your vertical balance scale. Install the beam for vertical measurement. Establish a fixed distance from the beam support for a calibrated displacement line which will become your scale. Then place the previously measured weights on the beam and mark the deflected position of the beam. One previously measured weight would be enough but you could test for linearity and accuracy if more than one previously measured weight was used for calibration. It sounds like an interesting project. Good luck. Roger psn-l-digest-request@.............. wrote: > <>.------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 1 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: force gauge/transducer > From: Jan Froom > Date: Mon, 30 Jan 2006 12:12:21 -0800 > Anyone know of a simple... quick... force gauge or force transducer... > 20 - 30 grams max with a resolution of .1 gram. that I could make or buy? > > I'm working on a wind tunnel for my grandson's science fair project and > we need a way to measure the lift and drag. > I can measure lift with a beam balance scale... but the drag is in a > horizontal direction and because the force is so low, I hate using a > pulley arrangement to change the direction from horizontal to vertical. > > Oh... and did I say cheap? > > I'd settle for a spring gauge if I could find a source... that's > accurate at this low a force. > > Thanks.... Jan in Gilroy > > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Suggestion for a seismograph program From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 31 Jan 2006 18:02:28 +0000 Hi all I plan to write a linux / *nix compatable program for working out data from a psn station. I currently don't know how to program in C++ or other programming languages (nothign useful anyway), but i plan to learn it on my own. But i will need suggestions and help with that prodect. I will have this program of mine in GPL licenace when the time comes. Here is what i have planned so far, and plan to put this in a Open Office document soon (and pdf). * The program is in two parts, server (datalogging) (gui optimcal) and client (working on the data, only gui). Both parts will have networks abliti (communication over lan or the internet). I will define this part better later on. * Automatic magnitue calculation, from one or many stations. * Network and Internet abilty. Both to remote connect stations into one or more server. * Low and hig pass digital filtering, along side with raw data mode (setup of many windows as needed). This is can be done on the client, that actually displays the data as it gets send from the server program. * Post prosessing of earthquakes. * Automatic detection of earthquakes, and removal of envromental noise. * Webserver abilti. This is going to be detailed later. * Map abliti, for more then three station. But also for location of earthquakes if remote data is used. For example time and location data used from emsc-cmes and others. * GPS timeing and location. Timeing also awable trugh the internet by using ntp (ntp client) will then have to be installed if used. * Hig resultion details of earthquakes. More detail on this later. * Wide support of hardware, both from psn and others. * Tremor plot in a window on user defined freq. * Telesemic earthquake detection. Local earthquake detection. There is problay more that belongs on this list (and problay few things that i have forgot to put on this list), but that is going to be added with time. I want my program to be compatable with the *.psn format and the windsr dataloggin program (server) but also to contain it's own dataloggin program. I also want my program to be able to save in the *.psn format. I also want my program to be awable to professonal seismographs networks out there, along side with pepole who have intrest in earthquakes and volcanos. In few words. Suggestions, ideas, comments and so on needed. So i know where to start. I haven't started anything yet, but my learning on C++ and other programming languages is going to start soon. I need good books on the matter. But i am more broke then usual so that might get delayed. I am going to use what i have at the moment to learn this. Sorry for spelling errors. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Suggestion for a seismograph program From: ian ian@........... Date: Tue, 31 Jan 2006 18:41:15 +0000 Being old fashioned, I would choose C rather than C++ but you may be correct. The scope you describe is very wide and admirable. It might be suited to doing a full specification which would then allow the software to be written by a collaboration of people. Cheers Ian J�n Fr�mann wrote: >Hi all > >I plan to write a linux / *nix compatable program for working out data >from a psn station. I currently don't know how to program in C++ or >other programming languages (nothign useful anyway), but i plan to learn >it on my own. But i will need suggestions and help with that prodect. I >will have this program of mine in GPL licenace when the time comes. > >Here is what i have planned so far, and plan to put this in a Open >Office document soon (and pdf). > >* The program is in two parts, server (datalogging) (gui optimcal) and >client (working on the data, only gui). Both parts will have networks >abliti (communication over lan or the internet). I will define this part >better later on. >* Automatic magnitue calculation, from one or many stations. >* Network and Internet abilty. Both to remote connect stations into one >or more server. >* Low and hig pass digital filtering, along side with raw data mode >(setup of many windows as needed). This is can be done on the client, >that actually displays the data as it gets send from the server program. >* Post prosessing of earthquakes. >* Automatic detection of earthquakes, and removal of envromental noise. >* Webserver abilti. This is going to be detailed later. >* Map abliti, for more then three station. But also for location of >earthquakes if remote data is used. For example time and location data >used from emsc-cmes and others. >* GPS timeing and location. Timeing also awable trugh the internet by >using ntp (ntp client) will then have to be installed if used. >* Hig resultion details of earthquakes. More detail on this later. >* Wide support of hardware, both from psn and others. >* Tremor plot in a window on user defined freq. >* Telesemic earthquake detection. Local earthquake detection. > >There is problay more that belongs on this list (and problay few things >that i have forgot to put on this list), but that is going to be added >with time. > >I want my program to be compatable with the *.psn format and the windsr >dataloggin program (server) but also to contain it's own dataloggin >program. I also want my program to be able to save in the *.psn format. > >I also want my program to be awable to professonal seismographs networks >out there, along side with pepole who have intrest in earthquakes and >volcanos. > >In few words. Suggestions, ideas, comments and so on needed. So i know >where to start. > >I haven't started anything yet, but my learning on C++ and other >programming languages is going to start soon. I need good books on the >matter. But i am more broke then usual so that might get delayed. I am >going to use what i have at the moment to learn this. > >Sorry for spelling errors. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Suggestion for a seismograph program From: ian ian@........... Date: Tue, 31 Jan 2006 18:41:15 +0000 Being old fashioned, I would choose C rather than C++ but you may be correct. The scope you describe is very wide and admirable. It might be suited to doing a full specification which would then allow the software to be written by a collaboration of people. Cheers Ian J�n Fr�mann wrote: >Hi all > >I plan to write a linux / *nix compatable program for working out data >from a psn station. I currently don't know how to program in C++ or >other programming languages (nothign useful anyway), but i plan to learn >it on my own. But i will need suggestions and help with that prodect. I >will have this program of mine in GPL licenace when the time comes. > >Here is what i have planned so far, and plan to put this in a Open >Office document soon (and pdf). > >* The program is in two parts, server (datalogging) (gui optimcal) and >client (working on the data, only gui). Both parts will have networks >abliti (communication over lan or the internet). I will define this part >better later on. >* Automatic magnitue calculation, from one or many stations. >* Network and Internet abilty. Both to remote connect stations into one >or more server. >* Low and hig pass digital filtering, along side with raw data mode >(setup of many windows as needed). This is can be done on the client, >that actually displays the data as it gets send from the server program. >* Post prosessing of earthquakes. >* Automatic detection of earthquakes, and removal of envromental noise. >* Webserver abilti. This is going to be detailed later. >* Map abliti, for more then three station. But also for location of >earthquakes if remote data is used. For example time and location data >used from emsc-cmes and others. >* GPS timeing and location. Timeing also awable trugh the internet by >using ntp (ntp client) will then have to be installed if used. >* Hig resultion details of earthquakes. More detail on this later. >* Wide support of hardware, both from psn and others. >* Tremor plot in a window on user defined freq. >* Telesemic earthquake detection. Local earthquake detection. > >There is problay more that belongs on this list (and problay few things >that i have forgot to put on this list), but that is going to be added >with time. > >I want my program to be compatable with the *.psn format and the windsr >dataloggin program (server) but also to contain it's own dataloggin >program. I also want my program to be able to save in the *.psn format. > >I also want my program to be awable to professonal seismographs networks >out there, along side with pepole who have intrest in earthquakes and >volcanos. > >In few words. Suggestions, ideas, comments and so on needed. So i know >where to start. > >I haven't started anything yet, but my learning on C++ and other >programming languages is going to start soon. I need good books on the >matter. But i am more broke then usual so that might get delayed. I am >going to use what i have at the moment to learn this. > >Sorry for spelling errors. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Suggestion for a seismograph program From: Angel sismos@.............. Date: Tue, 31 Jan 2006 20:07:47 +0000 Hello J�n, I think that that is an admirable endeavor to start on but most of what you describe there has already be done by several groups and at least two of them are in the public domain and free. I think that it would be far easier to write the missing modules for the core Earthworm system than to reinvent something that already works well and is in wide use. Right now you can take the data from the PSN serial card (and others) and go directly into Earthworm or Seiscomp over a TCP/IP and in either of those systems you can do most of the things you list. Jon, you can find more information for the two systems I mention at these URLs: http://folkworm.ceri.memphis.edu/ew-doc/ http://www.gfz-potsdam.de/geofon/new/scp.html Warmly, Angel Tuesday, January 31, 2006, 6:02:28 PM, you wrote: > Hi all > I plan to write a linux / *nix compatable program for working out data > from a psn station. I currently don't know how to program in C++ or > other programming languages (nothign useful anyway), but i plan to learn > it on my own. But i will need suggestions and help with that prodect. I > will have this program of mine in GPL licenace when the time comes. > Here is what i have planned so far, and plan to put this in a Open > Office document soon (and pdf). > * The program is in two parts, server (datalogging) (gui optimcal) and > client (working on the data, only gui). Both parts will have networks > abliti (communication over lan or the internet). I will define this part > better later on. > * Automatic magnitue calculation, from one or many stations. > * Network and Internet abilty. Both to remote connect stations into one > or more server. > * Low and hig pass digital filtering, along side with raw data mode > (setup of many windows as needed). This is can be done on the client, > that actually displays the data as it gets send from the server program. > * Post prosessing of earthquakes. > * Automatic detection of earthquakes, and removal of envromental noise. > * Webserver abilti. This is going to be detailed later. > * Map abliti, for more then three station. But also for location of > earthquakes if remote data is used. For example time and location data > used from emsc-cmes and others. > * GPS timeing and location. Timeing also awable trugh the internet by > using ntp (ntp client) will then have to be installed if used. > * Hig resultion details of earthquakes. More detail on this later. > * Wide support of hardware, both from psn and others. > * Tremor plot in a window on user defined freq. > * Telesemic earthquake detection. Local earthquake detection. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: force gauge/transducer From: ChrisAtUpw@....... Date: Tue, 31 Jan 2006 16:47:00 EST In a message dated 30/01/2006, JDarwin@............. writes: Anyone know of a simple... quick... force gauge or force transducer... 20 - 30 grams max with a resolution of .1 gram. that I could make or buy? I'm working on a wind tunnel for my grandson's science fair project and we need a way to measure the lift and drag. I can measure lift with a beam balance scale.. Oh... and did I say cheap? Hi Jan, You can buy 1 mm thick sheets of a rubbery like material called QTC - Quantum Tunneling Composite. You sandwich it between two metal plates and measure the resistance between them. With zero force you have a near insulator. As the force increases, the electrical resistance drops. This is a cheap way of making a force transducer. Regards, Chris Chapman

In a message dated 30/01/2006, JDarwin@............. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Anyone=20 know of a simple... quick... force gauge or force transducer...
20 - 30= =20 grams max with a resolution of .1 gram. that I could make or=20 buy?

I'm working on a wind tunnel for my grandson's science fair=20 project and
we need a way to measure the lift and drag.
I can= =20 measure lift with a beam balance scale..

Oh... and did I say=20 cheap?

Hi Jan,

You can buy 1 mm thick sheets of a rubbery= =20 like material called QTC - Quantum Tunneling Composite. You sandwich it betw= een=20 two metal plates and measure the resistance between them. With zero force yo= u=20 have a near insulator. As the force increases, the electrical resistance dro= ps.=20 This is a cheap way of making a force transducer.

Regards,

Chris Chapman

Subject: Re: Suggestion for a seismograph program From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 01 Feb 2006 01:30:25 +0000 Hi Angel (and others) I did try test those programs that you did recommend. But i was unable to get them running, becose i did find them rather hard to both start and the lack of usefuls guides was hig and there was no way to install them properly on my linux system, both from source or by binary install. I am used to complex things (after all, i do run Gentoo Linux) so understanding is only a tempuary problem if things works as suppose to. However i do find the structure of the programs to be confusing and lacking. I don't want to offent the pepole who take there time to write those programs, there effort is good. But i do belive that there is a need for better more modern program to do this work, that is also more flexable and more routeburst (can withstand failures). I also agree with you that there is no need to invent the programs, but i belive that improvments is needed. I can try and failed, i want that rather then not to try and not knowing if it was possible. After all, that is why i did get me geophone to start with. :-) Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Suggestion for a seismograph program From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 01 Feb 2006 01:34:53 +0000 Hi Ian (and others) It is save to say that this prodject will need more pepole then just me. But i will see how this works out. I have alot to learn, and it is going to take some time to learn it. I also want more suggestions or ideas if possible. Since there are so many things about recording earthquakes that i don't know about. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: exact frequencies for arrival of different seismic waves ?? From: Tamati chief.cook.nz@............ Date: Thu, 02 Feb 2006 09:53:08 +1300 TAMATI's WORD's OF WISDOM FOR THE GOOD OF ALL MANKIND HTTP://LIVE-PLANET.BLOGSPOT.COM http://www.webspawner.com/users/chiefcooknz/index.html Please give me feed back on what you think chief.cook.nz.@............ NZ-021-150-33-59 or NZ-07-855-0195 Morning from New Zealand I'm one of those WHAT,WHERE & HOW people I don't know at your talking about but:- I've got a question in your Email you said that you I recieved a Teleseismic event from New Zealand What is a Teleseismic event? Where did the Teleseimic event happen? How long was the Teleseimic Event? How did you or they measuring the Hz rates? are you talking about radio noise your measuring or Wind or what? I understand and know "tele" means visial affect and seismic is the resolt of waves radiating outwards from a centre of force release eg: a stone thrown into water generates a seismic affect Cheers Tamati From the Castle of Tamati, Hinemoa and Karauwa the Dog From the Castle of Tom, Robyn and the Dog I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195 Bush Telegragh:- chief.cook.nz@............ My Regular Pitstop:- Tamati P.O.BOX 19-356 CENTRAL HAMILTON NEW ZEALAND ----- Original Message ----- From: "Geoff" To: Sent: Friday, January 27, 2006 7:34 PM Subject: Re: exact frequencies for arrival of different seismic waves ?? > Thanks Dave; > > I just got three EQs from Baja California looks like > two foreshocks and the main, they are a little over three > degrees away and 4,0 or less in magnitude. > It looks to me like the P waves are in the hertz range > which is beyond the rolloff of my current filter. > The other day I received Teleseismic event from New Zealand > that was said to be 90deg away and only 5.2 mag which > was inband..it looked like the freq was down around > 5 hertz or so. > > You pointd out something I never saw before with the link > you provided, thank you very much. I never understood > what those spheres represented till now. > > I am currently using a two octave filter which provides > flatness below 1 Hz and am able to see both regional > and teleseismic P waves. > > My filter is down to three opamps now where it used to > be 8 or so :-) and I get better results. > I got this penpal over in England that believes > in a KISS philosophy (Keep it Simple Stupid) > that philosophy has proven to be true. > > Once Again Thanks to PSN and people like > yourself I am an old dog learning new tricks. > > gmv > > ----- Original Message ----- > From: "Dave Nelson" > To: > Sent: Thursday, January 26, 2006 9:30 PM > Subject: Re: exact frequencies for arrival of different seismic waves ?? > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of the > message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: digital filtering From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 02 Feb 2006 04:13:13 +0000 Hi all I have started digital filtering my gif files online. With a lowpass filter cutoff of 10Hz. Any suggestion on that move is welcomed by me, since i am still learning on this. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: digital filtering From: ChrisAtUpw@....... Date: Thu, 2 Feb 2006 06:07:18 EST In a message dated 02/02/2006, jonfr500@......... writes: Hi all I have started digital filtering my gif files online. With a lowpass filter cutoff of 10Hz. Any suggestion on that move is welcomed by me, since i am still learning on this. Hi Jon, Your amplifier Low Pass Filter is actually set to 20 Hz, so there should be very little data above about 22 Hz. This should be well suited to you local quakes. Sorry that I got it wrong, but I was reading the characteristics from the psn website. Regards, Chris Chapman In a message dated 28/01/2006, lcochrane@.............. writes: Chris wrote: > The low pass filter on your amplifier board should be 10 Hz and have 8 > poles. In practice, a signal at 13.4 Hz will be reduced to 1/10 and one at 18 > Hz to 1/100. > The amplifier has a high pass filter set at 0.05 Hz = 20 sec., which is > well below the lowest response of your geophones. Actually Jon's Amp/Filter board has a 20 Hz 7 pole low pass filter. I usually set the filter to 20 Hz instead of the 10 Hz if I know that the filter board will be used with a geophone to record local events. Regards, Larry Cochrane

In a message dated 02/02/2006, jonfr500@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Hi=20 all
I have started digital filtering my gif files online. With a=20 lowpass
filter cutoff of 10Hz. Any suggestion on that move is welcomed=20= by=20 me,
since i am still learning on this.

Hi Jon,

Your amplifier Low Pass Filter is actually set=20= to=20 20 Hz, so there should be very little data above about 22 Hz. This should be= =20 well suited to you local quakes.

Sorry that I got it wrong, but I was reading th= e=20 characteristics from the psn website.

Regards,

Chris Chapman

=20

In a message dated 28/01/2006, lcochrane@.............. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Chris=20 wrote:
> The low pass filter on your amplifier board should be= 10=20 Hz and have 8
> poles. In practice, a signal at 13.4 Hz will be red= uced=20 to 1/10 and one at 18
> Hz to 1/100.
> &nbs= p;=20 The amplifier has a high pass filter set at 0.05 Hz =3D 20 sec., whi= ch is=20
> well below the lowest response of your geophones.

Actually= =20 Jon's Amp/Filter board has a 20 Hz 7 pole low pass filter. I usually set t= he=20
filter to 20 Hz instead of the 10 Hz if I know that the filter board w= ill=20 be used
with a geophone to record local events.

Regards,
Lar= ry=20 Cochrane

Subject: Re: digital filtering From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 02 Feb 2006 22:40:42 +0000 Hi Chris I have set the raw data on digital filtering, but that one is on 5.5Hz but the online graphs are now on 4Hz. It appears that the noise is somewhat above 10Hz (there is noise on 10Hz, but alot less then if i record from 2Hz to 60Hz), maybe above 6Hz. I just haven tested it properly yet. I do not know how this filtering will effect my abliti to detect earthquakes. But i hope that the won't be any effect of this in regarding detecing earthquakes. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: digital filtering From: Mark Robinson mark.robinson@............... Date: Fri, 03 Feb 2006 11:48:19 +1300 J�n Fr�mann wrote: > I have set the raw data on digital filtering, but that one is on 5.5Hz > but the online graphs are now on 4Hz. It appears that the noise is > somewhat above 10Hz (there is noise on 10Hz, but alot less then if i > record from 2Hz to 60Hz), maybe above 6Hz. I just haven tested it > properly yet. I do not know how this filtering will effect my abliti to > detect earthquakes. But i hope that the won't be any effect of this in > regarding detecing earthquakes. The more you filter the higher frequencies out the less small local events you will see. If you look at http://www.geonet.org.nz/drums/snzo-drum.gif and http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/SNZO_24hr.gif you will see that the first one shows local events while the second shows teleseisms. Both traces come from the same sensor, the Geonet display showing the data with all the long period stuff filtered out and the usgs one showing the same data with all the high frequencies filtered out. regards Mark __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: digital filtering From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 02 Feb 2006 23:11:11 +0000 Hi Mark I do now know the frequencies of the earthquakes that happen here in Iceland, but it is hig (most of the time). I have taken the digital filtering off the raw data and i will see how earthquake appears on the online graphs. Now i just need a earthquake. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: digital filtering From: ChrisAtUpw@....... Date: Thu, 2 Feb 2006 22:07:38 EST In a message dated 02/02/2006, jonfr500@......... writes: I have set the raw data on digital filtering, but that one is on 5.5Hz but the online graphs are now on 4Hz. It appears that the noise is somewhat above 10Hz (there is noise on 10Hz, but alot less then if i record from 2Hz to 60Hz), maybe above 6Hz. I just haven tested it properly yet. I do not know how this filtering will effect my abliti to detect earthquakes. Hi Jon, Record 'sample' traces at the maximum bandwidth of 20 Hz, including noise at various times and a few local quakes. If you only view from maybe 3 to 5.5 Hz, you may miss some quakes. Then view these traces putting in varying frequency low pass digital filters, using Winquake and see how to make the quake traces easier to read against the background noise. Regards, Chris Chapman

In a message dated 02/02/2006, jonfr500@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I have=20 set the raw data on digital filtering, but that one is on 5.5Hz
but the= =20 online graphs are now on 4Hz. It appears that the noise is
somewhat abo= ve=20 10Hz (there is noise on 10Hz, but alot less then if i
record from 2Hz t= o=20 60Hz), maybe above 6Hz. I just haven tested it
properly yet. I do= not=20 know how this filtering will effect my abliti to
detect=20 earthquakes.

Hi Jon,

Record 'sample' traces at the maximum bandwidth= of=20 20 Hz, including noise at various times and a few local quakes.

If you only view from maybe 3 to 5.5 Hz, you ma= y=20 miss some quakes.

Then view these traces putting in varying=20 frequency low pass digital filters, using Winquake and see how to make the q= uake=20 traces easier to read against the background noise.

Regards,

Chris Chapman

Subject: Re: digital filtering From: Barry Lotz barry_lotz@............. Date: Thu, 2 Feb 2006 20:01:16 -0800 (PST) Hi Jon I agree with Chris. I record my quakes as raw data then filter them with winquake. If you don't like the pass band you can change it. For teleseismic events on my system I use a pass band between 0.03 & 0.3 hz. For local events I use a high pass around .5 to 1 hz. ChrisAtUpw@....... wrote: In a message dated 02/02/2006, jonfr500@......... writes: I have set the raw data on digital filtering, but that one is on 5.5Hz but the online graphs are now on 4Hz. It appears that the noise is somewhat above 10Hz (there is noise on 10Hz, but alot less then if i record from 2Hz to 60Hz), maybe above 6Hz. I just haven tested it properly yet. I do not know how this filtering will effect my abliti to detect earthquakes. Hi Jon, Record 'sample' traces at the maximum bandwidth of 20 Hz, including noise at various times and a few local quakes. If you only view from maybe 3 to 5.5 Hz, you may miss some quakes. Then view these traces putting in varying frequency low pass digital filters, using Winquake and see how to make the quake traces easier to read against the background noise. Regards, Chris Chapman

Hi Jon

I agree with Chris. I record my quakes as raw data then filter them with winquake. If you don't like the pass band you can change it. For teleseismic events on my system I use a pass band between 0.03 & 0.3 hz. For local events I use a high pass around .5 to 1 hz.

ChrisAtUpw@....... wrote:

In a message dated 02/02/2006, jonfr500@......... writes:

I have set the raw data on digital filtering, but that one is on 5.5Hz
but the online graphs are now on 4Hz. It appears that the noise is
somewhat above 10Hz (there is noise on 10Hz, but alot less then if i
record from 2Hz to 60Hz), maybe above 6Hz. I just haven tested it
properly yet. I do not know how this filtering will effect my abliti to
detect earthquakes.

Hi Jon,

    Record 'sample' traces at the maximum bandwidth of 20 Hz, including noise at various times and a few local quakes.

    If you only view from maybe 3 to 5.5 Hz, you may miss some quakes.

    Then view these traces putting in varying frequency low pass digital filters, using Winquake and see how to make the quake traces easier to read against the background noise.

    Regards,

    Chris Chapman

Subject: Re: digital filtering From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 03 Feb 2006 04:30:44 +0000 Hi I have turned off digital filtering for raw data. However i am going to keep it on for the online tremor graphs that i have. I did check data on the earthquake that i have recorded and they appear good on 4Hz freq. So they will appear on my online graphs. The freq. there is 4.5Hz, i had posted the wrong freq setup before. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Detecting earthquake of a distiance of 855 km From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 04 Feb 2006 15:52:23 +0000 Hi all I think i did manage to detect a earthquake at the distace of 855 km, the earthquake was on the Reykjanes ridge, i had to manually register the earthquake. I can see the seismatic wave (at least i think it is the seismetic wave) if i filter the raw data down to 4Hz with winquake or lower. I am going to send the raw data to the psn file list. But before i do that i want to be sure that i did detected the earthquake. The trace is 10 min long, but i don't know if i did need to make a longer trace or not. The files can be downloaded from here. http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt1z.psn http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt2e.psn http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt3n.psn Thanks and regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting earthquake of a distiance of 855 km From: ian ian@........... Date: Sat, 04 Feb 2006 18:56:42 +0000 Hi, I picked it up on my Lehman. My geopone is still suffering from that channel's electrical problem, so I can't do a comparison for you. You can see a nice traces of the quake at http://www.guralp.net/realtime/ and a good map at http://www.iris.edu/seismon/zoom/?view=eveday&lon=-29&lat=51 I'm currently off line. My satellite broadband provider, Aramiska, went bankrupt last week :-( Cheers Ian J�n Fr�mann wrote: >Hi all > >I think i did manage to detect a earthquake at the distace of 855 km, >the earthquake was on the Reykjanes ridge, i had to manually register >the earthquake. I can see the seismatic wave (at least i think it is the >seismetic wave) if i filter the raw data down to 4Hz with winquake or >lower. I am going to send the raw data to the psn file list. But before >i do that i want to be sure that i did detected the earthquake. The >trace is 10 min long, but i don't know if i did need to make a longer >trace or not. > >The files can be downloaded from here. > >http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt1z.psn >http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt2e.psn >http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt3n.psn > >Thanks and regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting earthquake of a distiance of 855 km From: Dave Nelson davenn@............... Date: Sun, 05 Feb 2006 08:51:52 +1100 Hi Jon yup looks like u fot it but when comparing to Ian's=20 recording it loks like u got the P and S in the wrong place where u have= =20 the P marker should be where the S marker position and the P marker in=20 front of that when u filter ur seismogram in winquake this becomes much more obvious cheers Dave At 15:52 4/02/2006 +0000, you wrote: >Hi all >I think i did manage to detect a earthquake at the distace of 855 km, >the earthquake was on the Reykjanes ridge, i had to manually register >the earthquake. I can see the seismatic wave (at least i think it is the >seismetic wave) if i filter the raw data down to 4Hz with winquake or >The files can be downloaded from here. >http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt1z.psn >http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt2e.psn >http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt3n.psn > >Thanks and regards. >-- >J=F3n Fr=EDmann J=F3nsson __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting earthquake of a distance of 855 km From: Dave Nelson davenn@............... Date: Sun, 05 Feb 2006 08:57:01 +1100 Hi Jon yet where u have the markers coincides with the event timing so maybe you only did pick up the P wave I know over the years there are many many distant events I recorded that= =20 only the P wave showed up on the seismogram cheers Dave Nelson Sydney At 15:52 4/02/2006 +0000, you wrote: >Hi all >I think i did manage to detect a earthquake at the distace of 855 km, >the earthquake was on the Reykjanes ridge, i had to manually register >the earthquake. I can see the seismatic wave (at least i think it is the >seismetic wave) if i filter the raw data down to 4Hz with winquake or >The files can be downloaded from here. >http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt1z.psn >http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt2e.psn >http://www.simnet.is/jonfr500/earthquake/winquake/060204.142900.hvt3n.psn > >Thanks and regards. >-- >J=F3n Fr=EDmann J=F3nsson __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting earthquake of a distance of 855 km From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 05 Feb 2006 04:08:49 +0000 Hi all I did also detect a 4.5mb earthquake that did happen today (i think). But that detection was worse then the detection of the 4.9mb earthquake. I do not know if i was able to detect the s wave from those quakes, but i think that it is there, even if it is almost not visable. When i got down to 2Hz with winquake. I think that i see the surface waves. But I am not sure. I made a new trace of the 4.9mb earthquake, it about 20 min long. The trace of the 4.5mb earthquake is 19 min long. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Detecting earthquake of a distance of 855 km From: "Kareem at HeyJooJoo" system98765@............. Date: Sat, 4 Feb 2006 20:20:32 -0800 Where are you guys located where you're recording these events? Kareem=20 Western Contra Costa County - CA, USA -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of J=F3n Fr=EDmann Sent: Saturday, February 04, 2006 8:09 PM To: psn-l@.............. Subject: Re: Detecting earthquake of a distance of 855 km Hi all I did also detect a 4.5mb earthquake that did happen today (i think). But that detection was worse then the detection of the 4.9mb earthquake. I do not know if i was able to detect the s wave from those quakes, but = i think that it is there, even if it is almost not visable. When i got = down to 2Hz with winquake. I think that i see the surface waves. But I am not = sure. I made a new trace of the 4.9mb earthquake, it about 20 min long. The = trace of the 4.5mb earthquake is 19 min long. Regards. -- J=F3n Fr=EDmann J=F3nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting earthquake of a distance of 855 km From: ian ian@........... Date: Sun, 05 Feb 2006 07:53:19 +0000 I'm in East Lothian, Scotland, UK. Ian Kareem at HeyJooJoo wrote: >Where are you guys located where you're recording these events? > >Kareem >Western Contra Costa County - CA, USA > > > >-----Original Message----- >From: psn-l-request@.............. [mailto:psn-l-request@............... On >Behalf Of J�n Fr�mann >Sent: Saturday, February 04, 2006 8:09 PM >To: psn-l@.............. >Subject: Re: Detecting earthquake of a distance of 855 km > >Hi all > >I did also detect a 4.5mb earthquake that did happen today (i think). >But that detection was worse then the detection of the 4.9mb earthquake. >I do not know if i was able to detect the s wave from those quakes, but i >think that it is there, even if it is almost not visable. When i got down to >2Hz with winquake. I think that i see the surface waves. But I am not sure. > >I made a new trace of the 4.9mb earthquake, it about 20 min long. The trace >of the 4.5mb earthquake is 19 min long. > >Regards. >-- >J�n Fr�mann J�nsson >http://www.jonfr.com > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body of the >message (first line only): unsubscribe See >http://www.seismicnet.com/maillist.html for more information. > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Detecting micro-earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 05 Feb 2006 13:49:16 +0000 Hi all I am wondering what is the best way for me to detect micro-earthquakes that i might record, manually or automatic. Since i have to have a way to detect them from the noise. I already know that i have to filter the data down to at least 3Hz to get rid of the noise. But i am not sure how to detect the wave pattern of such small earthquake (not smaller then 2Ml) after such filtering. Thanks and regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting earthquake of a distance of 855 km From: Bobhelenmcclure@....... Date: Sun, 5 Feb 2006 13:51:14 EST I applied my WQFilter utility to the data submitted by J=F3n Fr=EDmann J=F3n= sson =20 for the event =20 M5.4 2006/02/04 14:29:55 59.058 -30.896 10.0 REYKJANES RIDGE =20 He did record the event, as evident in the filtered result, although there =20 are also some artifacts present as well. WQFilter was used to extend the lon= g =20 period response of the geophone sensor from 0.22 seconds to 4.0 seconds. =20 I have submitted the filtered and raw data for the Z sensor as the volume=20 file 060204.142901.hvt1.psn =20 Bob

I applied my WQFilter utility to the data submitted by J=F3n Fr=EDmann=20= J=F3nsson=20 for the event

M5.4 2006/02/04 14:29:55 59.058 -30.896 10.0&nb= sp;=20 REYKJANES RIDGE

He did record the event, as evident in the filtered result, although th= ere=20 are also some artifacts present as well. WQFilter was used to extend the lon= g=20 period response of the geophone sensor from 0.22 seconds to 4.0 seconds.

I have submitted the filtered and raw data for the Z=20 sensor as the volume file 060204.142901.hvt1.psn

Bob

Subject: 12 bits for $39 From: Bobhelenmcclure@....... Date: Sun, 5 Feb 2006 14:35:39 EST Hi all, I use the 12-bit Dataq DI-154RS for data acquisition. I am on my second one, and I paid $150 for each. Go to _www.dataq.com/products/startkit/di154rs.htm_ (http://www.dataq.com/products/startkit/di154rs.htm) and you will see that the price is now only $39. I have all the software you need to use this device for data logging, filtering, and conversion to PSN event files. Regards, Bob Bob McClure PSN Network Station REM Locust Valley, NY USA 40.882N 73.5817W

Hi all,

I use the 12-bit Dataq DI-154RS for data acquisition. I am on my= =20 second one, and I paid $150 for each. Go to

www.dataq.com/pr= oducts/startkit/di154rs.htm

and you will see that the price is now only $39.

I have all the software you need to use this device for data=20 logging, filtering, and conversion to PSN event files.

Regards,

Bob

Bob=20 McClure
PSN Network Station REM
Locust Valley, NY USA
40.882N=20 73.5817W

Subject: Re: Detecting earthquake of a distance of 855 km From: Tamati chief.cook.nz@............ Date: Mon, 06 Feb 2006 10:10:45 +1300 chief.cook.nz.@............ NZ-021-150-33-59 or NZ-07-855-0195 Hi John with your trace recordings can you put the location(s) of Country and/or your State plus time time or is the time stamp on the Email at same time as tour recording(s) BTW:- how do I display your website in english please Cheers Tamati From the Castle of Tamati, Hinemoa and Karauwa the Dog From the Castle of Tom, Robyn and the Dog I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195 Bush Telegragh:- chief.cook.nz@............ My Regular Pitstop:- Tamati P.O.BOX 19-356 CENTRAL HAMILTON NEW ZEALAND ----- Original Message ----- From: "J�n Fr�mann" To: Sent: Sunday, February 05, 2006 5:08 PM Subject: Re: Detecting earthquake of a distance of 855 km > Hi all > > I did also detect a 4.5mb earthquake that did happen today (i think). > But that detection was worse then the detection of the 4.9mb earthquake. > I do not know if i was able to detect the s wave from those quakes, but > i think that it is there, even if it is almost not visable. When i got > down to 2Hz with winquake. I think that i see the surface waves. But I > am not sure. > > I made a new trace of the 4.9mb earthquake, it about 20 min long. The > trace of the 4.5mb earthquake is 19 min long. > > Regards. > -- > J�n Fr�mann J�nsson > http://www.jonfr.com > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fwd: [o4r] Superb resource From: John or Jan Lahr JohnJan@........ Date: Sun, 05 Feb 2006 14:38:37 -0800 I just learned the MIT has posted a lot of information on their courses (see below). In the case of seismology, there are even lecture notes (see: http://ocw.mit.edu/OcwWeb/Earth--Atmospheric--and-Planetary-Sciences/12-510Spring-2005/LectureNotes/). I haven't looked at many of them, but this is a good place to learn about the theory. Cheers, John >From: George Slusher > >MIT has put the course materials for most of their courses online--and >it's FREE. > >http://ocw.mit.edu/index.html > >This does not include lectures, contact with the faculty, nor credit, >of course. (Ya gotta pay for that.) It also doesn't include the texts, >but it often does have lecture notes, assignments (homework), >solutions, tests and exams, and study materials. > > > > >George Slusher >Eugene, OR > > > > >Yahoo! Groups Links > ><*> To visit your group on the web, go to: > http://groups.yahoo.com/group/or4think-members/ > ><*> To unsubscribe from this group, send an email to: > or4think-members-unsubscribe@............... > ><*> Your use of Yahoo! Groups is subject to: > http://docs.yahoo.com/info/terms/ > ##################################/ John C. Lahr #################################/ Emeritus Seismologist ################################/ U.S. Geological Survey ===========================/ Geologic Hazards Team ##############################/ Golden, Colorado #############################//############################## ############################//############################### PO Box 548 /################################ Corvallis, Oregon 97339 /################################## Phone: (541) 758-2699 /============================= Cell: (541) 740-4844 /################################### Fax: (928) 569-0113 /################################## jjpub@........ /#################################### http://jclahr.com/science/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting micro-earthquakes From: Roger Sparks rsparks@.......... Date: Mon, 06 Feb 2006 06:23:36 -0800 Hi Jon, I live about 150 km east of Seattle, Washington where we have a lot of quakes less than magnitude 3.0. I wanted to see some of those quakes. When I first began this hobby, I filtered hard to remove the high frequency noise but soon found that I was also removing the signals from the small local quakes. That was because the small quakes were generating signals at a frequency above 1 Hz, up to 10 Hz and higher. I found my seismic noise floor to be the ocean wave generated noise near 0.2 Hz. Therefore, I expected that the small local quakes would be seen as high frequency deviations from the fairly smooth curve generated by the 0.2 Hz background noise. This expectation turned out to be correct. I presently have my computer screen filters set to high pass above 0.7 Hz. Using a sample rate of about 10.8 Hz, I can see quakes from magnitude 1.2 on up depending upon distance. I also have the ability to low pass the data which is helpful on the larger teleseismic quakes. Nearly all the teleseismic quakes also have energy at frequencies above my 0.7 Hz high pass filter cutoff so I can usually see them without the low pass filtering. Your problem might be different from mine if your noise floor is not from the ocean wave background. If your noise floor is from your electronics, seismometer hinge or wind, then your filtering needs would be different. You may have noticed that you can download the data from the quakes posted on PSN so that you can examine it carefully with Winquake. You can see what data operations have been used, what equipment the station is using, and examine the background noise for frequency. This can be very helpful in comparing the results from your station with the results of other station operators. I post on PSN from Ellensburg, Wash., and use the station signature "ebgz". When I began this hobby, I spent a lot of time looking for known events in my data. Now I mostly manually look for the event only if I think it is within my sensitivity and distance range but it is not obvious on my screen. Best wishes, Roger ----- ------ ------ ------ ------ ------ ------ ------ ------ ------. | Message 1 | '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' Subject: Detecting micro-earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= Date: Sun, 05 Feb 2006 13:49:16 +0000 Hi all I am wondering what is the best way for me to detect micro-earthquakes that i might record, manually or automatic. Since i have to have a way to detect them from the noise. I already know that i have to filter the data down to at least 3Hz to get rid of the noise. But i am not sure how to detect the wave pattern of such small earthquake (not smaller then 2Ml) after such filtering. Thanks and regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting micro-earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 06 Feb 2006 17:54:03 +0000 Hi all To Roger. I have 4.5Hz geophone, becose of that i don't detect the ocen wave most of the time (maybe during storm). Other matter. I think that i might have recorded a small earthquake, but there was a mining expotion at distance of 119km away from me around the same time, that i might have been able to pickup. However the p and s wave are so close to gether that i doubt that i was recording the mining explotion as i did first think, becose if i apply that timeing of the subspected mining, the p and s wave are behind the top that i see. There is a other option regarding this, this event might have been created when the earth freezes over and it cracks when that happens. But the current temp is -3.5C and the ground is freezing over. This might also just be noise. Here are the files for those intrested. www.simnet.is/jonfr500/earthquake/winquake/060206.163401.hvt1z.psn www.simnet.is/jonfr500/earthquake/winquake/060206.163401.hvt2e.psn www.simnet.is/jonfr500/earthquake/winquake/060206.163401.hvt3n.psn Thanks and regards. (sorry for spelling errors) -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auction From: Bob Barns royb1@........... Date: Tue, 07 Feb 2006 09:45:42 -0500 Hi gang, Vintage Seismograph Seiscor Telephone Test Set - L@@k! Item number: 6603668893 ends 2/13 I have no idea what this is. :-\ Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: "Jack Ivey" ivey@.......... Date: Tue, 7 Feb 2006 10:47:31 -0500 It's a telephone test set. I'm assuming the seller is going from the=20 company name (Seiscor). Jack -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Bob Barns Sent: Tuesday, February 07, 2006 9:46 AM To: psn mail Subject: ebay auction Hi gang, =20 Vintage Seismograph Seiscor Telephone Test Set - L@@k! Item number: 6603668893 =09 =09 ends 2/13 I have no idea what this is. :-\ Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: "Jack Ivey" ivey@.......... Date: Tue, 7 Feb 2006 10:47:31 -0500 It's a telephone test set. I'm assuming the seller is going from the=20 company name (Seiscor). Jack -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Bob Barns Sent: Tuesday, February 07, 2006 9:46 AM To: psn mail Subject: ebay auction Hi gang, =20 Vintage Seismograph Seiscor Telephone Test Set - L@@k! Item number: 6603668893 =09 =09 ends 2/13 I have no idea what this is. :-\ Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Shackleford-Gundersen Seismometer, is it long period ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 07 Feb 2006 17:07:27 +0000 Hi all Is the Shackleford-Gundersen Seismometer long period seismometer or short period seismometer. I was looking at the info on the psn page regarding this seismometer. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Shackleford-Gundersen Seismometer, is it long period ? From: ChrisAtUpw@....... Date: Tue, 7 Feb 2006 12:30:00 EST In a message dated 07/02/2006, jonfr500@......... writes: Is the Shackleford-Gundersen Seismometer long period seismometer or short period seismometer. I was looking at the info on the psn page regarding this seismometer. Hi Jon, It is a long period seismometer with a second channel high frequency output. You start with a vertical pendulum of maybe 1 sec period and extend the period using a linear distance transducer and electronic force feedback. See _http://psn.quake.net/freqtest.html_ (http://psn.quake.net/freqtest.html) Being a vertical pendulum, it does not have the precision tilt setup requirements of a Lehman. It is also physically smaller. Regards, Chris Chapman

In a message dated 07/02/2006, jonfr500@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Is the=20 Shackleford-Gundersen Seismometer long period seismometer or
short peri= od=20 seismometer. I was looking at the info on the psn page
regarding this=20 seismometer.

Hi Jon,

It is a long period seismometer with a second=20 channel high frequency output. You start with a vertical pendulum of maybe 1= sec=20 period and extend the period using a linear distance transducer and electron= ic=20 force feedback. See http://psn.quake.net/freqtest.ht= ml Being=20 a vertical pendulum, it does not have the precision tilt setup requirements=20= of a=20 Lehman. It is also physically smaller.

Regards,

Chris Chapman

Subject: Noise and earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 09 Feb 2006 20:44:36 +0000 Hi all Tomorrow (hopefully) i will send few recordings of earthquakes that i did record today (i am still wating for the final size and location etc, data from the Icelandic met Office), however there is a lot of noise in those recordings. Since the earhquakes did happen during the day. There is also a diffrent type of noise in the recordings, but it appears that when the ground is frosen it makes hig pulse period (both short and long period) noise that i sometimes records. One such noise did happen at the same time as i did record a earthquake. I did try to downfilter the files, but that didn't work well. Since the trace of the earhquakes is weak. I did send today the psn file list page two earthquakes that i did record yesterday and today. I got a trace of a 2.48 mag on Reykjanes, it was decent. Also a recording of a mag 3.3 earthquake, but it was really poor. Suggestions are always welcomed. Sorry for the spelling errors. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting micro-earthquakes From: Roger Sparks rsparks@.......... Date: Thu, 09 Feb 2006 17:27:00 -0800 Hi All, Hi Jon, I took a look at your files. Thanks for making them available. While I have become familiar with my own seismometer and capabilities, I am looking at a different world when looking at your files. First is the 200 samples per second which provides resolution of events as high as 100 Hz. That is very good. Next is the 4.5 Hz geophone which has a peak response at about 4.5 Hz. I expect it to detect local quakes very well. The expectations for large distant quakes are less. What surprised me was the large amount of energy found at 10 Hz, declining up to about 20 Hz. I did not expect to see that when I applied the FFT algorithm from Winquake to each file, and for the most part, to each subdivided time period within each file. What I expected to see was the ocean wave noise at 0.2 Hz but at a much reduced peak compared to my own seismometer which has a natural period of about 3 1/5 to 4 seconds. I am curious to know if you can explain the 10 Hz energy source? Also ocean waves? Maybe a nearby flag pole and flag waving in the wind? The second surprise was the large noise count, up in the +/- 300 unit range. It is nothing to be alarmed about, only different from my system. I wonder what the noise floor is when the seismometer is disconnected from the electronics? After looking at the files, the trace that most looked like a quake to me, occurred at about 36:11. I have a lot of local (people walking) quakes and occasionally see a trace like the 36:11 trace that is not a quake, so I would not go so far as to say it was one. I always check to see if other stations have also recorded the event before having confidence in my own results. It takes a while to learn the capabilities and limits of new equipment. Best wishes, Roger >.------ ------ ------ ------ ------ ------ ------ ------ ------ ------. >| Message 2 | >'------ ------ ------ ------ ------ ------ ------ ------ ------ ------' >Subject: Re: Detecting micro-earthquakes >From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= >Date: Mon, 06 Feb 2006 17:54:03 +0000 > >Hi all > >To Roger. > >I have 4.5Hz geophone, becose of that i don't detect the ocen wave most >of the time (maybe during storm). > >Other matter. >I think that i might have recorded a small earthquake, but there was a >mining expotion at distance of 119km away from me around the same time, >that i might have been able to pickup. However the p and s wave are so >close to gether that i doubt that i was recording the mining explotion >as i did first think, becose if i apply that timeing of the subspected >mining, the p and s wave are behind the top that i see. There is a other >option regarding this, this event might have been created when the earth >freezes over and it cracks when that happens. But the current temp is >-3.5C and the ground is freezing over. This might also just be noise. > >Here are the files for those intrested. > >www.simnet.is/jonfr500/earthquake/winquake/060206.163401.hvt1z.psn >www.simnet.is/jonfr500/earthquake/winquake/060206.163401.hvt2e.psn >www.simnet.is/jonfr500/earthquake/winquake/060206.163401.hvt3n.psn > >Thanks and regards. (sorry for spelling errors) > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: work light switch From: Barry Lotz barry_lotz@............. Date: Thu, 9 Feb 2006 20:21:27 -0800 (PST) Hi all I have a reasonably related question. I have a flourescent magnifying desk lamp that I use to solder my seismic circuitry . The switch has gone out and I can't seem to find a "off-on-momentary" replacement rocker switch for it (push til the light is warm then release to start position. push the other way to shut off.). Any thoughts? I've checked in digikey,mouser and serched on line with no success. It seems like it would be a simple & common item..... regards barry

Hi all

I have a reasonably related question. I have a flourescent magnifying desk lamp that I use to solder my seismic circuitry . The switch has gone out and I can't seem to find a "off-on-momentary" replacement rocker switch for it (push til the light is warm then release to start position. push the other way to shut off.). Any thoughts? I've checked in digikey,mouser and serched on line with no success. It seems like it would be a simple & common item.....

regards

barry

Subject: Re: work light switch From: "Kim Roland" KROL@............ Date: Fri, 10 Feb 2006 00:44:42 -0800 Hi, Try this company:=20 http://www.switchchannel.com/=20 Located in Los Angles,CA. USA Part # DR-42A-BB is a momentary on -off-on rocker switch. That might work. Kim =20 ----- Original Message -----=20 From: Barry Lotz=20 To: psn-l@................. Sent: Thursday, February 09, 2006 8:21 PM Subject: work light switch Hi all I have a reasonably related question. I have a flourescent magnifying = desk lamp that I use to solder my seismic circuitry . The switch has = gone out and I can't seem to find a "off-on-momentary" replacement = rocker switch for it (push til the light is warm then release to start = position. push the other way to shut off.). Any thoughts? I've checked = in digikey,mouser and serched on line with no success. It seems like it = would be a simple & common item..... regards barry

Hi,

Try this company:

http://www.switchchannel.com/&= nbsp;

Located in Los Angles,CA. = USA

Part # DR-42A-BB is a momentary on = -off-on rocker=20 switch.

That might work.

Kim

----- Original Message -----
From:=20 Barry=20 Lotz

To: psn-l@..............

Sent: Thursday, February 09, = 2006 8:21=20 PM

Subject: work light = switch

Hi all

I have a reasonably related question. I have a=20 flourescent magnifying desk lamp that I use to solder my seismic=20 circuitry . The switch has gone out and I can't seem to find a=20 "off-on-momentary" replacement rocker switch for it (push til the = light is=20 warm then release to start position. push the other way to shut off.). = Any=20 thoughts? I've checked in digikey,mouser and serched on line with no = success.=20 It seems like it would be a simple & common=20 item.....

regards

barry

Subject: Re: Detecting micro-earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 10 Feb 2006 10:38:13 +0000 Hi To Roger. I did in the end figure out that i didn't detect the earthquake at that range. It was out of my range, after all i didn't see any change in the graph as i did go down to 10 seconds on the X scale. I also now got a comparison, i did detect a mag 2.2Ml (unconfirmed size) earthquake this morning (05:01 GMT), it did happen when there is minimal noise from traffic and other cultrual noise sources. I was able to detect the S wave of the quake, but the recording is really poor. As for the 10 to 20Hz noise, i am unsure what you mean.But i am close to the ocen, about 300 meters from the beach. There are many noise sources where the geophone is located at the moment (for instant the wind noise is hig, even if the geophone is located inside the house), at the moment i can't move the geophone to better location, becose of house i life in. But i plan to move the geophone in next 6 to 8 months, when i can buy the needed hardware to move the geophone. If i rember correctly, the noise level is almost none when i do disconnect the geophone from the psn board. But i am not sure, i will check this when i move the geophone. The geophone is also located 2 meters (max) from a solid bedrock. That problay goes down to ~35km into the crust, becose it is an old volcano that the town is build on top of (in the side of it). Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting micro-earthquakes From: ChrisAtUpw@....... Date: Fri, 10 Feb 2006 13:28:54 EST In a message dated 10/02/2006, rsparks@.......... writes: While I have become familiar with my own seismometer and capabilities, I am looking at a different world when looking at your files. First is the 200 samples per second which provides resolution of events as high as 100 Hz. That is very good. Hi Jon, Your amplifiers have a cut-off at ~20 Hz. The minimum sample rate is 40 sps. 200 sps is not necessary and could use a lot of memory. Can you use 60 to 100 sps? Next is the 4.5 Hz geophone which has a peak response at about 4.5 Hz. I expect it to detect local quakes very well. The expectations for large distant quakes are less. It will not have a peaked response if it is correctly loaded. There should be a ~2.7 K Ohm resistor soldered across the output terminals of each geophone. What surprised me was the large amount of energy found at 10 Hz, declining up to about 20 Hz. I did not expect to see that when I applied the FFT algorithm from Winquake to each file, and for the most part, to each subdivided time period within each file. What I expected to see was the ocean wave noise at 0.2 Hz but at a much reduced peak compared to my own seismometer which has a natural period of about 3 1/5 to 4 seconds. You don't see microseisms at about 6 sec with a 4.5 Hz geophone. The response will be down by a factor of over 700. If you are on the coast you will likely see higher frequency noise associated with breaking waves. I am curious to know if you can explain the 10 Hz energy source? Also ocean waves? Maybe a nearby flag pole and flag waving in the wind? The Strouhal number is between 0.2 and 0.4, depending on the 'bluntness' of the object; S=fxD/v, where f is the vortex shedding frequency, D is the width of the object and v is the velocity. Vortices are shed alternately from either side of the object. The force on an object is at f/2 Hz, so a strong 20 m/sec, 76 kph wind will give D = 20 / 100, D ~ 0.2 m. I suspect that the 10 Hz could be resonances in air ducts in a central heating system? Maybe a fan? The velocity of sound is about 330 m/s, so 10 Hz has a wavelength of about 33 m. Do you have any ducts or corridors about 33, 16.5 or 8.25 m long? To see the response, choose a section of recording with no quake and click on the FFT tab in the top tool bar. You will see a plot of the amplitude against the period. The second surprise was the large noise count, up in the +/- 300 unit range. It is nothing to be alarmed about, only different from my system. I wonder what the noise floor is when the seismometer is disconnected from the electronics? You need to substitute 390 Ohm metal film resistors for the geophones to do this test. Can you buy electronic components easily? Regards, Chris Chapman

In a message dated 10/02/2006, rsparks@.......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>While I=20 have become familiar with my own seismometer and capabilities, I am lookin= g at=20 a different world when looking at your files. First is the 200 sample= s=20 per second which provides resolution of events as high as 100 Hz. Tha= t is=20 very good.

Hi Jon,

Your amplifiers have a cut-off at ~20 Hz. The=20 minimum sample rate is 40 sps. 200 sps is not necessary and could use a lot=20= of=20 memory. Can you use 60 to 100 sps?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Next is=20 the 4.5 Hz geophone which has a peak response at about 4.5 Hz. I expe= ct=20 it to detect local quakes very well. The expectations for large distant qu= akes=20 are less.

It will not have a peaked response if it is=20 correctly loaded. There should be a ~2.7 K Ohm resistor soldered across the=20 output terminals of each geophone.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>What=20 surprised me was the large amount of energy found at 10 Hz, declining= up=20 to about 20 Hz. I did not expect to see that when I applied the FFT algori= thm=20 from Winquake to each file, and for the most part, to each subdivided time= =20 period within each file. What I expected to see was the ocean wave no= ise=20 at 0.2 Hz but at a much reduced peak compared to my own seismometer which=20= has=20 a natural period of about 3 1/5 to 4 seconds.

You don't see microseisms at about 6 sec with a= 4.5=20 Hz geophone. The response will be down by a factor of over 700. If you=20= are=20 on the coast you will likely see higher frequency noise associated with brea= king=20 waves.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I am=20 curious to know if you can explain the 10 Hz energy source? Also ocean wav= es?=20 Maybe a nearby flag pole and flag waving in the wind?

The Strouhal number is between 0.2 and 0.4= ,=20 depending on the 'bluntness' of the object; S=3DfxD/v, where f is the vortex= =20 shedding frequency, D is the width of the object and v is the velocity. Vort= ices=20 are shed alternately from either side of the object. The force on an object=20= is=20 at f/2 Hz, so a strong 20 m/sec, 76 kph wind will give D =3D 20 /=20= 100, D=20 ~ 0.2 m.

I suspect that the 10 Hz could be resonanc= es=20 in air ducts in a central heating system? Maybe a fan? The velocity of=20 sound is about 330 m/s, so 10 Hz has a wavelength of about 33 m. Do you have= any=20 ducts or corridors about 33, 16.5 or 8.25 m long?

To see the response, choose a section of=20 recording with no quake and click on the FFT tab in the top t= ool=20 bar. You will see a plot of the amplitude against the period.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 second surprise was the large noise count, up in the +/- 300 unit ran= ge.=20 It is nothing to be alarmed about, only different from my system. I wonder= =20 what the noise floor is when the seismometer is disconnected from the=20 electronics?

You need to substitute 390 Ohm metal film resis= tors=20 for the geophones to do this test. Can you buy electronic components=20 easily?

Regards,

Chris Chapman

Subject: Alot of earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 10 Feb 2006 18:50:34 +0000 Hi all As you might have noticed i have been sending in alot of psn files. I hope that doesn't bother anyone. But there has been a slow earthquake swarm going on East of Gr�msey for the last 24 hours. There also appears that earthquakes are picking up in other areas of TFZ, for instace Northwest of Gr�msey. The largest earthquake so far detect is 3.6Ml earthquake that did happen at 18:00 UTC. For the last files i forgot to change there Description, it is ment to say TFZ, but it says Icelandic Region. I just forgot to change it before i did send the files (doh!). Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Alot of earthquakes From: "Kareem at HeyJooJoo" system98765@............. Date: Fri, 10 Feb 2006 18:29:04 -0800 Hi Jon and the others... Where is the area of Grimsey? I'm in the U.S. on the west coast but not familiar with the area you speak of. Is this in Germany, France, etc? Kareem =20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of J=F3n Fr=EDmann Sent: Friday, February 10, 2006 10:51 AM To: PSN-Postlist Subject: Alot of earthquakes Hi all As you might have noticed i have been sending in alot of psn files. I = hope that doesn't bother anyone. But there has been a slow earthquake swarm = going on East of Gr=EDmsey for the last 24 hours. There also appears that earthquakes are picking up in other areas of TFZ, for instace Northwest = of Gr=EDmsey. The largest earthquake so far detect is 3.6Ml earthquake that = did happen at 18:00 UTC. For the last files i forgot to change there Description, it is ment to say TFZ, but it says Icelandic Region. I just forgot to change it before i did send the files (doh!). Regards. -- J=F3n Fr=EDmann J=F3nsson http://www.jonfr.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Alot of earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 11 Feb 2006 05:12:10 +0000 Hi Question: Where is the area of Grimsey? This is located in Iceland, about ~200km away from me. There has been alot of activiti there now, and problay will continue today. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Massive earthquakea activite From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 11 Feb 2006 07:58:15 +0000 Hi all There is alot of earthquakea activitie going on now in Iceland, please look at this map. http://hraun.vedur.is/ja/englishweb/index.html Some earthquakes are problay mis locatated by the automatic system, but this is huge number of earthquakes. Regards, sorry for double emailing this. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting micro-earthquakes From: Roger Sparks rsparks@.......... Date: Sat, 11 Feb 2006 10:53:29 -0800 Hi All, Hi Jon, You definitely have detected some events. Congratulations. We had a M2.9 event about 102 km from Ellensburg last night. I posted both a filtered and unfiltered version on the PSN site. http://www.seismicnet.com/cgi-dos/makegif.exe?/quakes/0602/060211.114712.ebgz.psn http://www.seismicnet.com/cgi-dos/makegif.exe?/quakes/0602/060211.114712.efil.psn The unfiltered recording vividly demonstrates how the high frequency local quake can ride on the noise from ocean waves. Ellensburg is very roughly 200 miles from the ocean. Your location at 300 meters from the ocean must be very noisy as you have indicated. Your problems are far different from mine. Best wishes, Roger psn-l-digest-request@.............. wrote: >.------ ------ ------ ------ ------ ------ ------ ------ ------ ------. >| Message 1 | >'------ ------ ------ ------ ------ ------ ------ ------ ------ ------' >Subject: Re: Detecting micro-earthquakes >From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= >Date: Fri, 10 Feb 2006 10:38:13 +0000 > >Hi > >To Roger. > >I did in the end figure out that i didn't detect the earthquake at that >range. It was out of my range, after all i didn't see any change in the >graph as i did go down to 10 seconds on the X scale. I also now got a >comparison, i did detect a mag 2.2Ml (unconfirmed size) earthquake this >morning (05:01 GMT), it did happen when there is minimal noise from >traffic and other cultrual noise sources. I was able to detect the S >wave of the quake, but the recording is really poor. > >As for the 10 to 20Hz noise, i am unsure what you mean.But i am close to >the ocen, about 300 meters from the beach. There are many noise sources >where the geophone is located at the moment (for instant the wind noise >is hig, even if the geophone is located inside the house), at the moment >i can't move the geophone to better location, becose of house i life in. >But i plan to move the geophone in next 6 to 8 months, when i can buy >the needed hardware to move the geophone. > >If i rember correctly, the noise level is almost none when i do >disconnect the geophone from the psn board. But i am not sure, i will >check this when i move the geophone. The geophone is also located 2 >meters (max) from a solid bedrock. That problay goes down to ~35km into >the crust, becose it is an old volcano that the town is build on top of >(in the side of it). > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Detecting micro-earthquakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 11 Feb 2006 19:45:07 +0000 Hi all Hi Roger There was an earthquake warm last night and it did last until 11:37 (i think there where about ~200 earthquakes that did happen in this earthquake swarm), the earthquakes that i did record where all in poor qualiti. I think that might come from the depth that they where happening on, but also how they where breaking up in the crust. Today i did change my setup a little bit, i did increase the gain and did set the sps to 50, this move was based on a advice that i got earlyar today. That is also the reasion why my online graphs are so eampty. Now i just have to wait for a earthquake to see how good or bad change it was that i did do today. I don't think that i am going to have to wait for a long time before i record a earthquake at this new settings. I already know that i was able to detect earthquakes down to ~2.4Ml at the range of ~200km max, if the earthquake had good recording on the Icelandic Met office seismic network. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Icelandic SIL network document (document from the Icelandic met From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 11 Feb 2006 20:17:26 +0000 Hi all I want to point out, for those how are intrested in this document, but it is about the Icelandic SIL network and how it was setup, this document is farly old and is problay in some parts outdated. But it is intresting non the less. http://hraun.vedur.is/ja/skyrslur/silresp/index.html Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Icelandic SIL network document (document from the Icelandic met office) From: ChrisAtUpw@....... Date: Sat, 11 Feb 2006 21:55:33 EST In a message dated 11/02/2006, jonfr500@......... writes: http://hraun.vedur.is/ja/skyrslur/silresp/index.html Hi Jon, Can you check this reference, please? I get website unavailable... ` Regards, Chris Chapman

In a message dated 11/02/2006, jonfr500@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>http://hraun.vedur.is/ja/skyrslur/silresp/index.html

Hi Jon,

Can you check this reference, please? = ;I=20 get website unavailable...

` Regards,

Chris Chapman

Subject: Re: Icelandic SIL network document (document from the Icelandic From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 12 Feb 2006 03:08:40 +0000 Hi The Icelandic met Office web, at least the earthquake part of there web appears to be down at the moment. I don't know what did happen, but it went offline sometimes around from 2:03 - 3:00UTC. They hopefully will fix this when the morning comes. Just check later if you can't connect right now. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: snow storm From: ian ian@........... Date: Mon, 13 Feb 2006 16:52:09 +0000 are the current micro seisms the snow storm on the East Coast (of USA)? See http://www.guralp.net/aboutus/index.php#live . My trace is the same too. Ian are the current micro seisms the snow storm on the East Coast (of USA)? See http://www.guralp.net/aboutus/index.php#live . My trace is the same too.

Ian
Subject: RE: snow storm From: "Bob Hancock" carpediem1@......... Date: Mon, 13 Feb 2006 09:59:26 -0700 You can check out the current ocean activity, a major source of this type of noise with the following link: https://www.fnmoc.navy.mil/PUBLIC/WAM/all_glbl.html Bob Hancock _____ From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ian Sent: Monday, February 13, 2006 09:52 To: psn-l@.............. Subject: snow storm are the current micro seisms the snow storm on the East Coast (of USA)? See http://www.guralp.net/aboutus/index.php#live . My trace is the same too. Ian

You can check out the current ocean activity, a major source of this type of noise with the following = link:

= https://www.= fnmoc.navy.mil/PUBLIC/WAM/all_glbl.html

Bob = Hancock

From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ian
Sent: Monday, February = 13, 2006 09:52
To: psn-l@..............
Subject: snow = storm

are the current micro seisms the snow storm on = the East Coast (of USA)? See http://www.guralp.n= et/aboutus/index.php#live .. My trace is the same too.

Ian

Subject: Re: snow storm From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 13 Feb 2006 17:23:07 +0000 Hi Ian According to the wave pattern, this is a wind hammering on the building where the seismonitor is located. I get this type of pattern all the time. Becose i have so many storms. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: what formats? From: "Thomas Dick" dickthomas01@............. Date: Mon, 13 Feb 2006 11:46:50 -0600 Anybody know .. what formats like weed and spyder will WinQuake handle? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: snow storm From: ian ian@........... Date: Mon, 13 Feb 2006 18:15:50 +0000 Hi, thanks for the link. The maps show waves in the atlantic which are at the end of the scale(huge)! Ian Bob Hancock wrote: > You can check out the current ocean activity, a major source of this > type of noise with the following link: > > > > https://www.fnmoc.navy.mil/PUBLIC/WAM/all_glbl.html > > > > Bob Hancock > > > > ------------------------------------------------------------------------ > > From: psn-l-request@.............. > [mailto:psn-l-request@............... On Behalf Of ian > Sent: Monday, February 13, 2006 09:52 > To: psn-l@.............. > Subject: snow storm > > > > are the current micro seisms the snow storm on the East Coast (of > USA)? See http://www.guralp.net/aboutus/index.php#live . My trace is > the same too. > > Ian > Hi,

thanks for the link. The maps show waves in the atlantic which are at the end of the scale(huge)!

Ian

Bob Hancock wrote:

You can check out the current ocean activity, a major source of this type of noise with the following link:

https://www.fnmoc.navy.mil/PUBLIC/WAM/all_glbl.html

Bob Hancock

From: psn-l-request@.............. [mailto:psn-l-request@..............] On Behalf Of ian
Sent: Monday, February 13, 2006 09:52
To: psn-l@..............
Subject: snow storm

are the current micro seisms the snow storm on the East Coast (of USA)? See http://www.guralp.net/aboutus/index.php#live .. My trace is the same too.

Ian

Subject: Alot of earthquake in a week From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 13 Feb 2006 22:13:05 +0000 Hi all Last week was today the most busy week that i have had in recording earthquakes since i got my Geophone in December. I have sent my psn files to the psn data list. I hope that it doesn't bother pepole that i have sent in large number of files. This however was rater normal week in Iceland, only about 300 - 500 earthquakes recored in total this week. I think the psn file list is going to be intresting when there is going to be a large scale earthquake swarm in part of Iceland. With mag 5 as a main earthquake and about ~20 earthquakes that are mag 3 or bigger and alot of smaller earthquakes. I hope that i don't bother pepole with this. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Google maps From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 14 Feb 2006 16:28:20 +0000 Hi all I want to point out wonders of google maps. This link is almost directy above my town. http://maps.google.com/maps?f=q&hl=en&t=k&ll=65.407731,-20.926895&spn=0.524632,1.955566&t=k Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Google maps From: Dave Willey davewilley@............. Date: Tue, 14 Feb 2006 15:35:34 -0800 (PST) Ha! If you have a fast computer you better take some Dramamine first! It is a very impressive tool. But I'm only good for about 10 minutes of flying around before my head starts spinning & I stagger off like a drunk as go to toss my lunch... Dave - N6DSW J�n Fr�mann wrote: Hi all I want to point out wonders of google maps. This link is almost directy above my town. http://maps.google.com/maps?f=q&hl=en&t=k&ll=65.407731,-20.926895&spn=0.524632,1.955566&t=k Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L)

Ha! If you have a fast computer you better take some Dramamine first!

It is a very impressive tool. But I'm only good for about 10 minutes of flying
around before my head starts spinning & I stagger off like a drunk as go
to toss my lunch...

Dave - N6DSW

J�n Fr�mann <jonfr500@.........> wrote:

Hi all

I want to point out wonders of google maps. This link is almost directy
above my town.

http://maps.google.com/maps?f=q&hl=en&t=k&ll=65.407731,-20.926895&spn=0.524632,1.955566&t=k

Regards.
--
J�n Fr�mann J�nsson
http://www.jonfr.com
http://www.simnet.is/jonfr500/earthquake/

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Subject: Detecting earthquake trugh a wind noise From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 15 Feb 2006 14:05:02 +0000 Hi all Last 24 hours have been bad for me in terms of detecting earthquakes, there has been a storm going on and my geophone picks up the wind and the ocen movements on the beach, even if it is inside the house. Last night at 03:19 UTC was a earthquake at size 2.88Ml at distance of 246km, i think that might have been able to detect that earthquake, however becose of the wind i am not sure if that i did detect the earthquake, becose the noise from the wind might simple have drowned the signal from the earthquake. Is there any good way for me to see if there is a earthquake in the noise or not. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: good leveling screw source From: Barry Lotz barry_lotz@............. Date: Wed, 15 Feb 2006 20:30:20 -0800 (PST) jim I have found that surplus surveying transit/level leveling screws have worked well for me, plus they come with an adjusting knob/wheel and bottom swivel (maybe not good, ie. possible minute horizontal free play) . Surveying repair businesses usually carry spare parts. regards Barry James Hannon wrote: I have not found the need to use extra fine pitch screws for leveling. I use national fine pitch socket head screws and grind the end to a dome shape. By using a long handle allen wrench to turn the screws I can get all the fineness in the adjustment I need. Jim Hannon -- Jim Hannon http://www.fmtcs.com/web/jmhannon/ 42,11.90N,91,39.26W WB0TXL -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L)

jim

I have found that surplus surveying transit/level leveling screws have worked well for me, plus they come with an adjusting knob/wheel and bottom swivel (maybe not good, ie. possible minute horizontal free play) . Surveying repair businesses usually carry spare parts.

regards

Barry

James Hannon <jmhannon@.........> wrote:

I have not found the need to use extra fine pitch screws for leveling. I use national fine pitch socket head screws and grind the end to a dome shape. By using a long handle allen wrench to turn the screws I can get all the fineness in the adjustment I need.

Jim Hannon
--
Jim Hannon
http://www.fmtcs.com/web/jmhannon/
42,11.90N,91,39.26W
WB0TXL
--

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Subject: WinQuake volume files From: Roger Sparks rsparks@.......... Date: Thu, 16 Feb 2006 10:23:42 -0800 Hi All, Bob McClure suggested that I post the contents of an email that I sent he and others yesterday concerning WinQuake volume files. Here it is. Volume files are a new WinQuake feature that Bob has used for a while now. It is available in WinQuake 2.9.8 beta which can be found here. http://www.seismicnet.com/software/wq298.zip Volume files allow two or three traces to appear in one window, each placed above the other. Each file must be the same length and contain some of the same header information before it can be placed in a volume. The File/Add menu is intended as an aid to making volume files but does not yet work reliably. Here is a work-around to make a volume file. Assume the goal is to filter a recording and display both the filtered and unfiltered trace in one window. The steps in WinQuake: 1. WinQuake opens with files listed in the "Open" screen. Select the quake to be displayed and click on "Open File" button 2. Perform the filter operation and save the filtered file with a new name. This is done in the "File Save" menu by modifying the name in the "File Name" window. Click the "OK" button. 3. Close the window containing the filtered file. That should put you back to the "Open" screen with the list of event files which now contains the filtered file. 4. Select both the filtered and unfiltered files by using the shift key while selecting the second file. Both files should be highlighted. Click the "Open File" button. 5. You should now see the traces from both files in the main WinQuake window. Click the "Save" button. 6. In the "File Save" window, you will see both names in separate "File Name" windows. Find the "Dataset Volume" check/button and click to place a check in the box One of the file names will disappear, leaving only one file name. Modify the name (if desired) and click the "OK" button. Both files will be saved as a volume with the modified name. 7. Here is a link to the volume that I made as I typed these instructions. http://www.seismicnet.com/quakes/0602/060211.114712.ebgztwo.psn Once opened, you can look at either individual file by clicking the "View" button. The drop-down menu choice "Display Record" or "Select Record" both give drop-down menu choices to examine the traces individually. My thanks to Bob who helped and inspired me to learn how to use this new WinQuake feature. Thanks also to Larry Cochrane who wrote WinQuake with all its useful features. Roger __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: From: 1goss@........... Date: Fri, 17 Feb 2006 08:54:25 +0000 Hi all I am trying to find a used geophone for recording micro earthquakes in the central US. Mainly in the New Madrid Fault Zone. I have a Lehmann sensor, but I would like a Geophone. I am not sure what I need, Maybe something like Larry had on his website but is sold out of the GeoSpace HS 10-1 1 Hz Vertical Sensor. Where would I look to find one or does anyone have one they would part with for the right price. Thanks Bryan S Goss Corinth Ms __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Geophones on ebay From: Bob Barns royb1@........... Date: Fri, 17 Feb 2006 10:12:47 -0500 Bryan, Ebay often offers geophones. They are rarely the 1 sec. period vareity. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophones on ebay From: "Geoffrey" gmvoeth@........... Date: Fri, 17 Feb 2006 10:59:29 -0700 I have to say that such a 1 sec geophone new will cost you in the neighborhood of $3000 USD so I think people who buy them are not too eager to give them up at a reduced price. I think those geophone people would be doing all us amateures a favor to create a lesser quality device at 1/10 the cost. Maybe if the chinese were to make them they could make them cheaper and sell them at Walmart in the toy section for the Jimmy Neutrons of this Earth. gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophones on ebay From: John or Jan Lahr JohnJan@........ Date: Fri, 17 Feb 2006 15:08:06 -0800 It's not that hard to make a short period sensor with a period of about 1 second. I've event been experimenting with one made mostly of wood! I've posted pictures here: http://jclahr.com/science/psn/wooden/ The period is just over 3 seconds, but at 1 second period it would be even more stable under changed in temperature. I actually like the toy store idea and think it would be easy to mass produce a very inexpensive system. Cheers, John At 09:59 AM 2/17/2006, you wrote: >I have to say that such a 1 sec geophone new >will cost you in the neighborhood of >$3000 USD so I think people who buy them >are not too eager to give them up >at a reduced price. I think those >geophone people would be doing all us >amateures a favor to create a lesser quality >device at 1/10 the cost. >Maybe if the chinese were to make them >they could make them cheaper and sell >them at Walmart in the toy section for the >Jimmy Neutrons of this Earth. >gmvoeth >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body >of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Recording Micro Quakes From: Roger Sparks rsparks@.......... Date: Sat, 18 Feb 2006 08:08:00 -0800 Hi Bryan,

You should find that your Lehmann would be more sensitive than a Geophone at the higher frequencies expected from micro quakes.   This would be because the longer period instruments would use less damping than the higher frequency units.

Think of it this way.   The shorter the period of a seismometer, the larger the damper will be to achieve critical damping.   The damper always reduces the motion induced in the seismometer by the passing wave.   Larger damper for a higher frequency sensor so less sensitivity (than the longer period sensor) at the higher frequencies.

You might consider if the damping and filters you are using on the Lehmann are seriously attenuating the higher frequency waves that could be expected from micro quakes.   You are probably sensing the micro quakes now, but losing the information in the filters and damper.

Several people are posting recordings of micro quakes on The PSN web site . A WinQuake FFT analysis of the posted micro quakes helps give a perspective of the bandpass requirements needed of the equipment.

Best wishes,   Roger

psn-l-digest-request@.............. wrote:

.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 1                                                           |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
From:    1goss@...........
Date:    Fri, 17 Feb 2006 08:54:25 +0000

Hi all I am trying to find a used geophone for recording micro earthquakes in the central US.
Mainly in the New Madrid Fault Zone. I have a Lehmann sensor, but I would like a Geophone. 
I am not sure what I need, Maybe something like Larry had on his website but is sold out of the GeoSpace HS 10-1 1 Hz Vertical Sensor. Where would I look to find one or does anyone have one they would part with for the right price.
Thanks Bryan S Goss
Corinth Ms

Subject: RE: Recording Micro Quakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 18 Feb 2006 17:02:06 +0000 Hi Bryan I use 4.5Hz Geophone to detect local and regional earthquakes, at this moment i don't have a long period seismonitor. This geophone can, if the condsions are good, you can detect earthquakes down to ~2.4ML at the range of ~200 km. The frequancy of a local earthquake is from 2Hz to 60Hz, problay higer if you can recorod it. The problem is however that above 4Hz there is alot of noise. Both from nature and human traffic. You can check my recordings at the psn webpage. http://seismicnet.com/cgi-dos/event.exe They are the one with the name "Hvammstangi". Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Geo-phone From: Tamati chief.cook.nz@............ Date: Sun, 19 Feb 2006 08:04:32 +1300 TAMATI's WORD's OF WISDOM FOR THE GOOD OF ALL MANKIND HTTP://LIVE-PLANET.BLOGSPOT.COM http://www.webspawner.com/users/chiefcooknz/index.html Please give me feed back on what you think chief.cook.nz.@............ NZ-021-150-33-59 or NZ-07-855-0195 have you got a circut diagram of your geo-phone Cheers Tamati From the Castle of Tamati, Hinemoa and Karauwa the Dog From the Castle of Tom, Robyn and the Dog I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195 Bush Telegragh:- = chief.cook.nz@............ My Regular Pitstop:- Tamati = P.O.BOX 19-356 CENTRAL = HAMILTON NEW = ZEALAND

TAMATI's WORD's OF = WISDOM
FOR=20 THE GOOD OF ALL MANKIND
HTTP://LIVE-PLANET.BLOGSPOT.COM<= /A>
http://ww= w.webspawner.com/users/chiefcooknz/index.html
Please=20 give me feed back on what you think
chief.cook.nz.@............
NZ-021-150-33-59=20 or NZ-07-855-0195

have you got a circut diagram of your=20 geo-phone

Cheers Tamati
From the Castle of = Tamati,=20 Hinemoa and Karauwa the Dog
From the Castle of Tom, Robyn and the=20 Dog

I'm Just a Stone's Throw Away:- = NZ-021-150-33-59=20 or=20 NZ-07-855-0195
         &= nbsp;           &n= bsp;       =20 Bush Telegragh:- chief.cook.nz@............=
           &nb= sp;          =20 My Regular Pitstop:-=20 Tamati
          &nb= sp;           &nbs= p;            = ;            =             &= nbsp;     =20 P.O.BOX 19-356=20 CENTRAL
          &n= bsp;           &nb= sp;           &nbs= p;            = ;            =       =20 HAMILTON
          &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;      =20 NEW ZEALAND

Subject: Recording Micro Quakes From: 1goss@........... Date: Sun, 19 Feb 2006 07:00:59 +0000 Thanks for all the reply�s. I don�t have 3,000 for a geophone laying around, so I will shorten the period on one of my Lehman�s to see how well It can record local events. Thanks again Bryan S Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Recording Micro Quakes From: ChrisAtUpw@....... Date: Sun, 19 Feb 2006 11:07:29 EST =20 In a message dated 19/02/2006, 1goss@........... writes: Thanks for all the reply=E2=80=99s. I don=E2=80=99t have 3,000 for a geopho= ne laying=20 around, so I will shorten the period on one of my Lehman=E2=80=99s to see h= ow well It can=20 record local events.=20 Thanks again Bryan S Goss Hi Bryan, =20 No! This is not necessary and it will actually REDUCE the output, since= =20 you will have to increase the damping. For local events you need to look at= P=20 & S freqencies well over 1 Hz. I expect that your amplifier will roll off a= t=20 10 Hz. Just use Winquake to set the upper and lower frequencies displayed. =20 Regards, =20 Chris Chapman

In a message dated 19/02/2006, 1goss@........... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Thanks=20 for all the reply=E2=80=99s. I don=E2=80=99t have 3,000 for a geophone lay= ing around, so I=20 will shorten the period on one of my Lehman=E2=80=99s to see how well It c= an record=20 local events.
Thanks again Bryan S Goss
=

Hi Bryan,

No! This is not necessary and it will actually=20 REDUCE the output, since you will have to increase the damping. For local ev= ents=20 you need to look at P & S freqencies well over 1 Hz. I expect that your=20 amplifier will roll off at 10 Hz. Just use Winquake to set the upper and low= er=20 frequencies displayed.

Regards,

Chris Chapman

Subject: Educational seisograph construction details From: Jatin Pandya jatinip@......... Date: Sun, 19 Feb 2006 09:20:31 -0800 (PST) I was pointed at the following site to get details of their educational seisograph. I have sent them requests at least three times, but haven't heard back from them. Has anyone received any construction details of their educational seismograph from them? The site is at: http://www.mgm.monschau.de/seismic/ Jatin ===============

I was pointed at the following site to get details of their educational
seisograph. I have sent them requests at least three times, but haven't
heard back from them. Has anyone received any construction details of
their educational seismograph from them? 

The site is at: http://www.mgm.monschau.de/seismic/

Jatin
===============

Subject: Geophone Schematic for anyone interested From: "Geoffrey" gmvoeth@........... Date: Sun, 19 Feb 2006 10:53:29 -0700 Here is a link to the schematic I am currently using here in Apache junction, I was just wondering possibly if there is anyone out there interested in breadboarding and testing this same idea ?? It is only for P/S waves. My area is terribly noisy so I trust just about no signals I see here. http://users.isp.com/gmvoethb293690/geo001.gif Tamati asked me to show him what I am using so I told him to look here to find it. Cheers :-) gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Educational seisograph construction details From: ChrisAtUpw@....... Date: Sun, 19 Feb 2006 15:50:35 EST In a message dated 19/02/2006, jatinip@......... writes: I was pointed at the following site to get details of their educational seisograph. I have sent them requests at least three times, but haven't heard back from them. Has anyone received any construction details of their educational seismograph from them? The site is at: _http://www.mgm.monschau.de/seismic/_ (http://www.mgm.monschau.de/seismic/) Hi Jatin, I also put in a request, but I did not get either an acknowledgement or any information. Regards, Chris

In a message dated 19/02/2006, jatinip@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DCourier color=3D#000000 siz= e=3D2>I was=20 pointed at the following site to get details of their educational seisogra= ph.=20 I have sent them requests at least three times, but haven't heard back fro= m=20 them. Has anyone received any construction details of their educational=20 seismograph from them?

The site is at: http://www.mgm.monschau.de/seismic/
<= /BLOCKQUOTE>

Hi Jatin,

I also put in a request, but I did not get eith= er=20 an acknowledgement or any information.

Regards,

Chris

Subject: earthquake p and s wave fracturing ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 20 Feb 2006 00:57:42 +0000 Hi all This morning i did recorod a earthquake that was a 3.0ML based on early resaults, it problay is larger in size then the automatic resaults indicate. However, i have noticed something strange about this earthquake. This earthquake has a energy componment down to 2Hz and down to 1Hz, however i just don't recorod that frequancy (1Hz) that low good with my geophone. There also appears to be sometype of a fraction in the earthquake p and s waves. It appears more in the p wave, but is also visable in the s wave. This might be becose there is a large volcano between my location and where the earthquake did happen, i am not sure about that however. The files are here. http://seismicnet.com/cgi-dos/event.exe They are named Ml3 189km from Hvammstangi, Iceland, Vatnaj�kull I think that this might indcate that there is something in the making in the area where this earthqauke did happen. But the area is inside a volcano fissure swarm. The volcano in questions is named B�r�arb�nga (B�rdarbunga), here are info about it. http://www.volcano.si.edu/world/volcano.cfm?vnum=1703-03= Those volcanos are in between my location and where the earthquake did happen. http://www.volcano.si.edu/world/volcano.cfm?vnum=1701-09= - Hofsj�kull http://www.volcano.si.edu/world/volcano.cfm?vnum=1703-04= - Tungnafellsj�kull I just wonder why this is, that's all. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: earthquake p and s wave fracturing ? From: ChrisAtUpw@....... Date: Mon, 20 Feb 2006 07:07:55 EST In a message dated 20/02/2006, jonfr500@......... writes: This earthquake has an energy component down to 2Hz and down to 1Hz, however i just don't record that frequency (1Hz) that low good with my geophone. There also appears to be some type of a fraction in the earthquake p and s waves. It appears more in the p wave, but is also visible in the s wave. HI Jon, From the distance, this looks like a near regional quake. Your geophone will see ~1/20 sensitivity at 1 Hz, 1/5 sensitivity at 2 Hz. If the waves are strong enough you can see them. You may also see two sets of P & S waves which have travelled by different paths. There is a discontinuity called the Moho about 35 km down under land, 10 km down under the sea. The volcanic structures may interfere. Regards, Chris Chapman

In a message dated 20/02/2006, jonfr500@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>This=20 earthquake has an energy component down to 2Hz and down to 1Hz, however i=20= just=20 don't record that frequency (1Hz) that low good with my geophone. There al= so=20 appears to be some type of a fraction in the earthquake p and s waves. It=20 appears more in the p wave, but is also visible in the s wave.=20

HI Jon,

From the distance, this looks like a near regio= nal=20 quake. Your geophone will see ~1/20 sensitivity at 1 Hz, 1/5 sensitivity at=20= 2=20 Hz. If the waves are strong enough you can see them. You may also see two se= ts=20 of P & S waves which have travelled by different paths. There is a=20 discontinuity called the Moho about 35 km down under land, 10 km down u= nder=20 the sea. The volcanic structures may interfere.

Regards,

Chris Chapman

Subject: Re: Educational seisograph construction details From: geodynamics@....... Date: Mon, 20 Feb 2006 15:07:56 +0000 I just looked at the site. Seems that you might be able to figure out the details by studing the three posted documents. http://www.mgm.monschau.de/seismic/english/downloads.php Regards, -Tim- Timothy Carpenter -------------- Original message from ChrisAtUpw@........ -------------- In a message dated 19/02/2006, jatinip@......... writes: I was pointed at the following site to get details of their educational seisograph. I have sent them requests at least three times, but haven't heard back from them. Has anyone received any construction details of their educational seismograph from them? The site is at: http://www.mgm.monschau.de/seismic/ Hi Jatin, I also put in a request, but I did not get either an acknowledgement or any information. Regards, Chris

I just looked at the site. Seems that you might be able to figure out the details by studing the three posted documents.

http://www.mgm.monschau.de/seismic/english/downloads.php

Regards,

-Tim-

Timothy Carpenter

-------------- Original message from ChrisAtUpw@........ --------------

In a message dated 19/02/2006, jatinip@......... writes:

I was pointed at the following site to get details of their educational seisograph. I have sent them requests at least three times, but haven't heard back from them. Has anyone received any construction details of their educational seismograph from them?

The site is at: http://www.mgm.monschau.de/seismic/

Hi Jatin,

    I also put in a request, but I did not get either an acknowledgement or any information.

    Regards,

    Chris

Subject: RE: Geophones on ebay From: "Jack Ivey" ivey@.......... Date: Mon, 20 Feb 2006 12:48:13 -0500 John, What are you using for a spring? Is it a special magic "zero length" spring or just something from the hardware store? Thanks, Jack -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of John or Jan Lahr Sent: Friday, February 17, 2006 6:08 PM To: psn-l@.............. Subject: Re: Geophones on ebay It's not that hard to make a short period sensor with a period of=20 about 1 second. I've event been experimenting with one made mostly=20 of wood! I've posted pictures here: http://jclahr.com/science/psn/wooden/ The period is just over 3 seconds, but at 1 second period it would be=20 even more stable under changed in temperature. I actually like the toy store idea and think it would be easy to mass=20 produce a very inexpensive system. Cheers, John At 09:59 AM 2/17/2006, you wrote: >I have to say that such a 1 sec geophone new >will cost you in the neighborhood of >$3000 USD so I think people who buy them >are not too eager to give them up >at a reduced price. I think those >geophone people would be doing all us >amateures a favor to create a lesser quality >device at 1/10 the cost. >Maybe if the chinese were to make them >they could make them cheaper and sell >them at Walmart in the toy section for the >Jimmy Neutrons of this Earth. >gmvoeth >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body=20 >of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Educational seisograph construction details From: ChrisAtUpw@....... Date: Mon, 20 Feb 2006 13:02:57 EST In a message dated 20/02/2006, geodynamics@....... writes: I just looked at the site. Seems that you might be able to figure out the details by studing the three posted documents. _http://www.mgm.monschau.de/seismic/english/downloads.php_ (http://www.mgm.monschau.de/seismic/english/downloads.php) Hi Tim, Thanks for the suggestion. I have done this, but there is no information on their vertical sensor, just outline information on the two Lehmans. I was hoping to get drawings and dimensions. They do offer to send you a complete CD! Regards, Chris Chapman

In a message dated 20/02/2006, geodynamics@....... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>

I just looked at the site. Seems that you might be able to figure out t= he=20 details by studing the three posted documents. http://w= ww.mgm.monschau.de/seismic/english/downloads.php

Hi Tim,

Thanks for the suggestion. I have done this, bu= t=20 there is no information on their vertical sensor, just outline information o= n=20 the two Lehmans. I was hoping to get drawings and dimensions. They do offer=20= to=20 send you a complete CD!

Regards,

Chris Chapman

Subject: RE: Geophones on ebay From: John or Jan Lahr JohnJan@........ Date: Mon, 20 Feb 2006 11:19:35 -0800 Hi Jack, I'm just using a spring from the hardware store. John At 09:48 AM 2/20/2006, you wrote: >John, >What are you using for a spring? Is it a special magic "zero length" >spring >or just something from the hardware store? > >Thanks, >Jack __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Recording Micro Quakes From: Roger Sparks rsparks@.......... Date: Mon, 20 Feb 2006 13:54:46 -0800 This is a re-post. I mistakenly originally posted in HTML format, which does not reproduce well on PSN. I locked my E-mail to "text" for this posting and all future postings. Hi Bryan, You should find that your Lehmann would be more sensitive than a Geophone at the higher frequencies expected from micro quakes. This would be because the longer period instruments would use less damping than the higher frequency units. Think of it this way. The shorter the period of a seismometer, the larger the damper will be to achieve critical damping. The damper always reduces the motion induced in the seismometer by the passing wave. Larger damper for a higher frequency sensor so less sensitivity (than the longer period sensor) at the higher frequencies. You might consider if the damping and filters you are using on the Lehmann are seriously attenuating the higher frequency waves that could be expected from micro quakes. You are probably sensing the micro quakes now, but losing the information in the filters and damper. Several people are posting recordings of micro quakes on http://psn.quake.net. A WinQuake FFT analysis of the posted micro quakes helps give a perspective of the bandpass requirements needed of the equipment. Best wishes, Roger psn-l-digest-request@.............. wrote: >.------ ------ ------ ------ ------ ------ ------ ------ ------ ------. >| Message 1 | >'------ ------ ------ ------ ------ ------ ------ ------ ------ ------' >From: 1goss@........... >Date: Fri, 17 Feb 2006 08:54:25 +0000 > >Hi all I am trying to find a used geophone for recording micro earthquakes in the central US. >Mainly in the New Madrid Fault Zone. I have a Lehmann sensor, but I would like a Geophone. >I am not sure what I need, Maybe something like Larry had on his website but is sold out of the GeoSpace HS 10-1 1 Hz Vertical Sensor. Where would I look to find one or does anyone have one they would part with for the right price. >Thanks Bryan S Goss >Corinth Ms > > > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: two home-made vertical seismometers From: "Gerencher, Joseph J" gerencher@............ Date: Tue, 21 Feb 2006 15:09:27 -0500 I have photographs of two vertical seismometers that were made by Jim Lehman and given to me. Both have been in continuous operation for several years and both have a natural period of about one second. The smaller unit is in my classroom and the larger one is in the basement beneath the classroom. I modified the damping of the smaller unit using copper plumbing fittings, which makes it both easier to construct and easier to operate than the larger one. The web address for going directly to the photographs is too long to post on an e-mail, so if you want to see images of both these seismometers go to my opening web page at=20 http://home.moravian.edu/users/phys/mejjg01/ then click "homemade seismographs," click "Illustrated history of the seismometer system, 1991 to 1998" and click the links on that page. Additional detailed photographs of the construction design of the smaller home-made seismometer can be found at the following web site: http://www.netquake.org/seismometers/vertical.htm Unfortunately, I have not yet gotten around to annotating these photographs, but intend to do so in the next several days. =20 Joe Gerencher =20 =20

I have photographs of two vertical seismometers that = were made by Jim Lehman and given to me. Both have been in continuous operation for several years and both have a natural period of about one = second. The smaller unit is in my classroom and the larger one is in the = basement beneath the classroom. I modified the damping of the smaller unit = using copper plumbing fittings, which makes it both easier to construct and = easier to operate than the larger one. The web address for going directly to = the photographs is too long to post on an e-mail, so if you want to see images of both = these seismometers go to my opening web page at

http://home.moravia= n.edu/users/phys/mejjg01/

then click “homemade seismographs,” click = “Illustrated history of the seismometer system, 1991 to 1998” and click the = links on that page. Additional detailed photographs of the construction = design of the smaller home-made seismometer can be found at the following web = site: http://www.net= quake.org/seismometers/vertical.htm Unfortunately, I have not yet gotten around to annotating these = photographs, but intend to do so in the next several days.

Joe Gerencher

Subject: RE: two home-made vertical seismometers From: "Steve Hammond" shammon1@............. Date: Wed, 22 Feb 2006 09:02:10 -0800 If you want to build a simple seismograph, here is a URL of a very simple vertical seismograph that was designed by a fellow in Pasadena in the early 1990's. http://pw2.netcom.com/~shammon1/compressed/VERTICAL.GIF It uses a screen door spring and cost under $20. It is made from common parts in a local hardware store and produces good results. It does lack the electronics however, so if you check the same site, http://pw2.netcom.com/~shammon1/equip.htm#Electronics you will find a pre-amp using OP-07's that can be used with this. The coil can be built from #44 wire on a plastic frame. You can get the frame from Radio Shack if you just purchase a spool of their red/black/green #22 construction wire. Hand wind about 4,000 turns of the #44 wire onto a frame. Warp the coil in black electrical tape to protect it. The magnet is a cow magnet sold in an animal feed stores but other magnets will also work. I used these plans to build a system for a 5th grade classroom and the students were able to locate local events with it. Regards, Steve Hammond PSN San Jose, Aptos California -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Gerencher, Joseph J Sent: Tuesday, February 21, 2006 12:09 PM To: PSN-L@.............. Subject: two home-made vertical seismometers I have photographs of two vertical seismometers that were made by Jim Lehman and given to me. Both have been in continuous operation for several years and both have a natural period of about one second. The smaller unit is in my classroom and the larger one is in the basement beneath the classroom. I modified the damping of the smaller unit using copper plumbing fittings, which makes it both easier to construct and easier to operate than the larger one. The web address for going directly to the photographs is too long to post on an e-mail, so if you want to see images of both these seismometers go to my opening web page at http://home.moravian.edu/users/phys/mejjg01/ then click "homemade seismographs," click "Illustrated history of the seismometer system, 1991 to 1998" and click the links on that page. Additional detailed photographs of the construction design of the smaller home-made seismometer can be found at the following web site: http://www.netquake.org/seismometers/vertical.htm Unfortunately, I have not yet gotten around to annotating these photographs, but intend to do so in the next several days. Joe Gerencher

If you=20 want to build a simple seismograph, here is a URL of a very simple = vertical=20 seismograph that was designed by a fellow in Pasadena in the early=20 1990's.

http://p= w2.netcom.com/~shammon1/compressed/VERTICAL.GIF

It=20 uses a screen door spring and cost under $20. It is made from = common parts=20 in a local hardware store and produces good results. It does lack the=20 electronics however, so if you check the same site,

http://pw2= ..netcom.com/~shammon1/equip.htm#Electronics

you=20 will find a pre-amp using OP-07's that can be used with this. The coil = can be=20 built from #44 wire on a plastic frame. You can get the frame from Radio = Shack=20 if you just purchase a spool of their red/black/green #22 construction = wire.=20 Hand wind about 4,000 turns of the #44 wire onto a frame. Warp the = coil in=20 black electrical tape to protect it. The magnet is a cow magnet = sold in an=20 animal feed stores but other magnets will also work. I used these = plans to=20 build a system for a 5th grade classroom and the students were = able to=20 locate local events with it.

Regards, Steve Hammond PSN San Jose, Aptos = California

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of Gerencher, = Joseph=20 J
Sent: Tuesday, February 21, 2006 12:09 PM
To:=20 PSN-L@..............
Subject: two home-made vertical=20 seismometers

I have photographs of = two vertical=20 seismometers that were made by Jim Lehman and given to me. Both = have=20 been in continuous operation for several years and both have a natural = period=20 of about one second. The smaller unit is in my classroom and the = larger=20 one is in the basement beneath the classroom. I modified the = damping of=20 the smaller unit using copper plumbing fittings, which makes it both = easier to=20 construct and easier to operate than the larger one. The web = address for=20 going directly to the photographs is too long to post on an e-mail, so = if you=20 want to see images of both these seismometers go to my opening web = page at=20

http://home.moravia= n.edu/users/phys/mejjg01/

then click = “homemade=20 seismographs,” click “Illustrated history of the = seismometer system, 1991 to=20 1998” and click the links on that page. Additional = detailed photographs=20 of the construction design of the smaller home-made seismometer can be = found=20 at the following web site: http://www.net= quake.org/seismometers/vertical.htm =20 Unfortunately, I have not yet gotten around to annotating these = photographs,=20 but intend to do so in the next several days.

Joe Gerencher

If you=20 want to build a simple seismograph, here is a URL of a very simple = vertical=20 seismograph that was designed by a fellow in Pasadena in the early=20 1990's.

http://p= w2.netcom.com/~shammon1/compressed/VERTICAL.GIF

http://pw2= ..netcom.com/~shammon1/equip.htm#Electronics

Regards, Steve Hammond PSN San Jose, Aptos = California

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of Gerencher, = Joseph=20 J
Sent: Tuesday, February 21, 2006 12:09 PM
To:=20 PSN-L@..............
Subject: two home-made vertical=20 seismometers

I have photographs of = two vertical=20 seismometers that were made by Jim Lehman and given to me. Both = have=20 been in continuous operation for several years and both have a natural = period=20 of about one second. The smaller unit is in my classroom and the = larger=20 one is in the basement beneath the classroom. I modified the = damping of=20 the smaller unit using copper plumbing fittings, which makes it both = easier to=20 construct and easier to operate than the larger one. The web = address for=20 going directly to the photographs is too long to post on an e-mail, so = if you=20 want to see images of both these seismometers go to my opening web = page at=20

http://home.moravia= n.edu/users/phys/mejjg01/

then click = “homemade=20 seismographs,” click “Illustrated history of the = seismometer system, 1991 to=20 1998” and click the links on that page. Additional = detailed photographs=20 of the construction design of the smaller home-made seismometer can be = found=20 at the following web site: http://www.net= quake.org/seismometers/vertical.htm =20 Unfortunately, I have not yet gotten around to annotating these = photographs,=20 but intend to do so in the next several days.

Joe Gerencher

Subject: balancing motor timing From: Barry Lotz barry_lotz@............. Date: Wed, 22 Feb 2006 16:58:19 -0800 (PST) Hi All I have three long period homemade sensors with balancing motors, I check their position voltage manually every 2-3 days and if they are to far off center I send a 5 vt + or - signal to the sensor's low rpm(1 rpm) balancing motor for a few seconds to send it back towards zero. I would like to do this automatically. I could do this with a microprocessor but I thought it might be done with something more simple like some gates,switches and possibly 555 timers. I have not tried to create a 555 timing circuit with such a inballanced duty cycle ( on for ~ 1/2 to 1 sec and off for ~24 hrs). Any thoughts? regards Barry

Hi All

I have three long period homemade sensors with balancing motors, I check their position voltage manually every 2-3 days and if they are to far off center I send a 5 vt + or - signal to the sensor's low rpm(1 rpm) balancing motor for a few seconds to send it back towards zero. I would like to do this automatically. I could do this with a microprocessor but I thought it might be done with something more simple like some gates,switches and possibly 555 timers. I have not tried to create a 555 timing circuit with such a inballanced duty cycle ( on for ~ 1/2 to 1 sec and off for ~24 hrs). Any thoughts?

regards

Barry

Subject: RE: two home-made vertical seismometers From: "Kareem at HeyJooJoo" system98765@............. Date: Wed, 22 Feb 2006 17:28:23 -0800 Hi Steve, Are there any simple plans for building a horizontal, long period seismograph? (I know that there are tons of places online but figured you or the others may know of some real-time plans.) Kareem -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Steve Hammond Sent: Wednesday, February 22, 2006 9:02 AM To: psn-l@............... PSN-L@.............. Subject: RE: two home-made vertical seismometers If you want to build a simple seismograph, here is a URL of a very simple vertical seismograph that was designed by a fellow in Pasadena in the early 1990's. http://pw2.netcom.com/~shammon1/compressed/VERTICAL.GIF It uses a screen door spring and cost under $20. It is made from common parts in a local hardware store and produces good results. It does lack the electronics however, so if you check the same site, http://pw2.netcom.com/~shammon1/equip.htm#Electronics you will find a pre-amp using OP-07's that can be used with this. The coil can be built from #44 wire on a plastic frame. You can get the frame from Radio Shack if you just purchase a spool of their red/black/green #22 construction wire. Hand wind about 4,000 turns of the #44 wire onto a frame. Warp the coil in black electrical tape to protect it. The magnet is a cow magnet sold in an animal feed stores but other magnets will also work. I used these plans to build a system for a 5th grade classroom and the students were able to locate local events with it. Regards, Steve Hammond PSN San Jose, Aptos California -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Gerencher, Joseph J Sent: Tuesday, February 21, 2006 12:09 PM To: PSN-L@.............. Subject: two home-made vertical seismometers I have photographs of two vertical seismometers that were made by Jim Lehman and given to me. Both have been in continuous operation for several years and both have a natural period of about one second. The smaller unit is in my classroom and the larger one is in the basement beneath the classroom. I modified the damping of the smaller unit using copper plumbing fittings, which makes it both easier to construct and easier to operate than the larger one. The web address for going directly to the photographs is too long to post on an e-mail, so if you want to see images of both these seismometers go to my opening web page at http://home.moravian.edu/users/phys/mejjg01/ then click "homemade seismographs," click "Illustrated history of the seismometer system, 1991 to 1998" and click the links on that page. Additional detailed photographs of the construction design of the smaller home-made seismometer can be found at the following web site: http://www.netquake.org/seismometers/vertical.htm Unfortunately, I have not yet gotten around to annotating these photographs, but intend to do so in the next several days. Joe Gerencher __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: two home-made vertical seismometers From: Barry Lotz barry_lotz@............. Date: Wed, 22 Feb 2006 19:56:00 -0800 (PST) Hi Kareem This maybe a little to involved but I made a long period horizontal ( ~10" long ) from information read from Sean Thomas Morrissey's web site http://www.eas.slu.edu/People/STMorrissey/index.html. I built the vertical he described first then tried a horizontal next. It looks like the W.F. Sprengnether figure at the "PSN info" location.It's natural period was about 5 sec without the feedback circuitry. I used his circuitry with his description of the speaker coil and the VRDT construction for the feedback. I think the period was increased to about 20-30 sec but I haven't been able to check the base frequency vs response yet. the construction was not expensive but it was time consuming. I chose the component values from his Mcad equations but I'm not sure they are optimum (part of the required input was the coil output G and the sensors natural frequency) . I'm still working on a few bugs in the external amplifier/filter and balancing motor circuitry. It did record the recent Mozambique event but so did my simple Lehman ( pretty large event). I have wanted to try a horizontal lehman type sensor but with two long springs (one on each side) meeting at a heavy weight and slightly apart at the base of the boom. For a vertical like John Lahr showed previously, if the spring angle is brought more horizontal (parallel with the boom ) my understanding is the period is increased. I thought the same might apply with the horizontal and one would not have to worry as much about the drift the Lehman can produce as the boom assemble approaches the non returning position ( ie trying to increase the lehman period). Sorry I got so wordy Regards Barry. Kareem at HeyJooJoo wrote: Hi Steve, Are there any simple plans for building a horizontal, long period seismograph? (I know that there are tons of places online but figured you or the others may know of some real-time plans.) Kareem -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Steve Hammond Sent: Wednesday, February 22, 2006 9:02 AM To: psn-l@............... PSN-L@.............. Subject: RE: two home-made vertical seismometers If you want to build a simple seismograph, here is a URL of a very simple vertical seismograph that was designed by a fellow in Pasadena in the early 1990's. http://pw2.netcom.com/~shammon1/compressed/VERTICAL.GIF It uses a screen door spring and cost under $20. It is made from common parts in a local hardware store and produces good results. It does lack the electronics however, so if you check the same site, http://pw2.netcom.com/~shammon1/equip.htm#Electronics you will find a pre-amp using OP-07's that can be used with this. The coil can be built from #44 wire on a plastic frame. You can get the frame from Radio Shack if you just purchase a spool of their red/black/green #22 construction wire. Hand wind about 4,000 turns of the #44 wire onto a frame. Warp the coil in black electrical tape to protect it. The magnet is a cow magnet sold in an animal feed stores but other magnets will also work. I used these plans to build a system for a 5th grade classroom and the students were able to locate local events with it. Regards, Steve Hammond PSN San Jose, Aptos California -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Gerencher, Joseph J Sent: Tuesday, February 21, 2006 12:09 PM To: PSN-L@.............. Subject: two home-made vertical seismometers I have photographs of two vertical seismometers that were made by Jim Lehman and given to me. Both have been in continuous operation for several years and both have a natural period of about one second. The smaller unit is in my classroom and the larger one is in the basement beneath the classroom. I modified the damping of the smaller unit using copper plumbing fittings, which makes it both easier to construct and easier to operate than the larger one. The web address for going directly to the photographs is too long to post on an e-mail, so if you want to see images of both these seismometers go to my opening web page at http://home.moravian.edu/users/phys/mejjg01/ then click "homemade seismographs," click "Illustrated history of the seismometer system, 1991 to 1998" and click the links on that page. Additional detailed photographs of the construction design of the smaller home-made seismometer can be found at the following web site: http://www.netquake.org/seismometers/vertical.htm Unfortunately, I have not yet gotten around to annotating these photographs, but intend to do so in the next several days. Joe Gerencher __________________________________________________________ Public Seismic Network Mailing List (PSN-L)

Hi Kareem

This maybe a little to involved but I made a long period horizontal ( ~10" long ) from information read from Sean Thomas Morrissey's web site http://www.eas.slu.edu/People/STMorrissey/index.html. I built the vertical he described first then tried a horizontal next. It looks like the W.F. Sprengnether figure at the "PSN info" location.It's natural period was about 5 sec without the feedback circuitry. I used his circuitry with his description of the speaker coil and the VRDT construction for the feedback. I think the period was increased to about 20-30 sec but I haven't been able to check the base frequency vs response yet. the construction was not expensive but it was time consuming. I chose the component values from his Mcad equations but I'm not sure they are optimum (part of the required input was the coil output G and the sensors natural frequency) . I'm still working on a few bugs in the external amplifier/filter and balancing motor circuitry. It did record the recent Mozambique event but so did my simple Lehman ( pretty large event).

I have wanted to try a horizontal lehman type sensor but with two long springs (one on each side) meeting at a heavy weight and slightly apart at the base of the boom. For a vertical like John Lahr showed previously, if the spring angle is brought more horizontal (parallel with the boom ) my understanding is the period is increased. I thought the same might apply with the horizontal and one would not have to worry as much about the drift the Lehman can produce as the boom assemble approaches the non returning position ( ie trying to increase the lehman period).

Sorry I got so wordy

Regards

Barry.

Kareem at HeyJooJoo <system98765@.............> wrote:

Hi Steve,

Are there any simple plans for building a horizontal, long period
seismograph? (I know that there are tons of places online but figured you or
the others may know of some real-time plans.)

Kareem

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of Steve Hammond
Sent: Wednesday, February 22, 2006 9:02 AM
To: psn-l@............... PSN-L@..............
Subject: RE: two home-made vertical seismometers

If you want to build a simple seismograph, here is a URL of a very simple
vertical seismograph that was designed by a fellow in Pasadena in the early
1990's.
http://pw2.netcom.com/~shammon1/compressed/VERTICAL.GIF
It uses a screen door spring and cost under $20. It is made from common
parts in a local hardware store and produces good results. It does lack the
electronics however, so if you check the same site,
http://pw2.netcom.com/~shammon1/equip.htm#Electronics
you will find a pre-amp using OP-07's that can be used with this. The coil
can be built from #44 wire on a plastic frame. You can get the frame from
Radio Shack if you just purchase a spool of their red/black/green #22
construction wire. Hand wind about 4,000 turns of the #44 wire onto a frame.
Warp the coil in black electrical tape to protect it. The magnet is a cow
magnet sold in an animal feed stores but other magnets will also work. I
used these plans to build a system for a 5th grade classroom and the
students were able to locate local events with it.

Regards, Steve Hammond PSN San Jose, Aptos California

-----Original Message-----
From: psn-l-request@..............
[mailto:psn-l-request@................. Behalf Of Gerencher, Joseph J
Sent: Tuesday, February 21, 2006 12:09 PM
To: PSN-L@..............
Subject: two home-made vertical seismometers

I have photographs of two vertical seismometers that were made by
Jim Lehman and given to me. Both have been in continuous operation for
several years and both have a natural period of about one second. The
smaller unit is in my classroom and the larger one is in the basement
beneath the classroom. I modified the damping of the smaller unit using
copper plumbing fittings, which makes it both easier to construct and easier
to operate than the larger one. The web address for going directly to the
photographs is too long to post on an e-mail, so if you want to see images
of both these seismometers go to my opening web page at

http://home.moravian.edu/users/phys/mejjg01/

then click "homemade seismographs," click "Illustrated history of
the seismometer system, 1991 to 1998" and click the links on that page.
Additional detailed photographs of the construction design of the smaller
home-made seismometer can be found at the following web site:
http://www.netquake.org/seismometers/vertical.htm Unfortunately, I have not
yet gotten around to annotating these photographs, but intend to do so in
the next several days.

Joe Gerencher

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Subject: Re: balancing motor timing From: ChrisAtUpw@....... Date: Wed, 22 Feb 2006 22:57:33 EST In a message dated 23/02/2006, barry_lotz@............. writes: Any thoughts? Hi Barry, Have a look at Allan's circuit at _http://physics.mercer.edu/petepag/MKXVIII.pdf_ (http://physics.mercer.edu/petepag/MKXVIII.pdf) He has done automatic levelling - and a lot more! Regards, Chris Chapman

In a message dated 23/02/2006, barry_lotz@............. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Any=20 thoughts?

Hi Barry,

Have a look at Allan's circuit at http://physics.mercer= ..edu/petepag/MKXVIII.pdf He=20 has done automatic levelling - and a lot more!

Regards,

Chris Chapman

Subject: Mozambique 7.5 quake From: Jan Froom JDarwin@............. Date: Thu, 23 Feb 2006 08:07:14 -0800 We recorded it in Gilroy CA at South Valley Middle School. http://www.gusd.k12.ca.us/southvalley/seismic For those of us in California, Mozambique is on the opposite side of the earth... so when we receive the seismic waves... from which direction are they coming and if from multiple paths, why don't they interfere or cancel each other out? Jan in Gilroy.... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Mozambique 7.5 quake -- global view of wave migration From: "Timothy Carpenter" geodynamics@....... Date: Thu, 23 Feb 2006 12:37:45 -0500 The following program provides an excellent representation of how = seismic waves travel through and around the globe. Watch the propagation of the waves and you should be able to answer your own question. Go to: http://www.geol.binghamton.edu/faculty/jones/jones.html Scroll down to: "Seismic Waves: A program for the visualization of wave propagation" (About 1/2 way down the page). Download seiswave.readme and SeismicWavesSetup.exe. Read the readme file and then Run the setup program. When the installation is finished, run the animation and select the = Sumatra Quake. After it has finished with one quake, the program moves on to another. According to Dr. Jones' site, "It is possible to add new events by using = the Wilbur II facility at the IRIS Electronic Bulletin Board" Regards, -Tim- Timothy Carpenter, P.E., Pres., GeoDynamics Consultants, Inc. 5043 Whitlow Ct. Commerce Twp., Mi 48382 248-363-4529 (voice & fax) 248-766-1629 (cell) geodynamics@........... (primary) geodynamics@....... (secondary) -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of Jan Froom Sent: Thursday, February 23, 2006 11:07 AM To: psn-l@.............. Subject: Mozambique 7.5 quake We recorded it in Gilroy CA at South Valley Middle School.=20 http://www.gusd.k12.ca.us/southvalley/seismic For those of us in California, Mozambique is on the opposite side of the = earth... so when we receive the seismic waves... from which direction=20 are they coming and if from multiple paths, why don't they interfere or=20 cancel each other out? Jan in Gilroy.... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: two home-made vertical seismometers From: Bobhelenmcclure@....... Date: Thu, 23 Feb 2006 13:53:21 EST If you are looking for a simple vertical seismometer, take a look at the one built by Roger Sparks. _http://www.elltel.net/sparksite/CSpring%20Seismometer.html_ (http://www.elltel.net/sparksite/CSpring%20Seismometer.html) It has a period of several seconds, which I has been able to digitally extend to many seconds. It is virtually impossible to get a long period simply by hanging a mass from a vertical spring. For example, the spring has to stretch one meter to get a natural period of two seconds. The period of such a sensor is the same as a pendulum of the same length as the extension of a vertical spring. Bob

If you are looking for a simple vertical seismometer, take a look at th= e=20 one built by Roger Sparks.

http://w= ww.elltel.net/sparksite/CSpring%20Seismometer.html

It has a period of several seconds, which I has been able to digit= ally=20 extend to many seconds.

It is virtually impossible to get a long period simply by hanging a mas= s=20 from a vertical spring. For example, the spring has to stretch one meter to=20= get=20 a natural period of two seconds. The period of such a sensor is the same as=20= a=20 pendulum of the same length as the extension of a vertical spring.

Bob

Subject: Re: Recording Micro Quakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 24 Feb 2006 01:53:46 +0000 Hi all I have managed to record a earthquake that was 2.2Ml in magnitue at the range of 155Km, this is smallest earthquake i have been able to detect so far. I don't expect to recorod anything smaller at this distance. I assume that i will be able to detect earthquake smaller then 2.2Ml in magnitue if they are closer to my location. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Recording Micro Quakes From: "Kareem at HeyJooJoo" system98765@............. Date: Thu, 23 Feb 2006 18:23:33 -0800 Joe, That's impressive. Are you using a short period sensor or long? Kareem California, U.S.A.=20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of J=F3n Fr=EDmann Sent: Thursday, February 23, 2006 5:54 PM To: psn-l@.............. Subject: Re: Recording Micro Quakes Hi all I have managed to record a earthquake that was 2.2Ml in magnitue at the range of 155Km, this is smallest earthquake i have been able to detect = so far. I don't expect to recorod anything smaller at this distance. I = assume that i will be able to detect earthquake smaller then 2.2Ml in magnitue = if they are closer to my location. Regards. -- J=F3n Fr=EDmann J=F3nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: two home-made vertical seismometers From: "Kareem at HeyJooJoo" system98765@............. Date: Thu, 23 Feb 2006 18:31:07 -0800 Hey Barry, Thanks for the info. I'll have a look. I actually have a PS2 recording system by Kinemetrics. It's a portable system which came with a vertical geophone (L4). It's great for local events as imagined but not so good for distant more common events. So I figured that it may be time to attempt to build one. Message is certainly not too wordy but rather appreciated. I'm still quite knew on the concepts of short period versus long period. Kareem -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Barry Lotz Sent: Wednesday, February 22, 2006 7:56 PM To: psn-l@.............. Subject: RE: two home-made vertical seismometers Hi Kareem This maybe a little to involved but I made a long period horizontal ( ~10" long ) from information read from Sean Thomas Morrissey's web site http://www.eas.slu.edu/People/STMorrissey/index.html. I built the vertical he described first then tried a horizontal next. It looks like the W.F. Sprengnether figure at the "PSN info" location.It's natural period was about 5 sec without the feedback circuitry. I used his circuitry with his description of the speaker coil and the VRDT construction for the feedback. I think the period was increased to about 20-30 sec but I haven't been able to check the base frequency vs response yet. the construction was not expensive but it was time consuming. I chose the component values from his Mcad equations but I'm not sure they are optimum (part of the required input was the coil output G and the sensors natural frequency) . I'm still working on a few bugs in the external amplifier/filter and balancing motor circuitry. It did record the recent Mozambique event but so did my simple Lehman ( pretty large event). I have wanted to try a horizontal lehman type sensor but with two long springs (one on each side) meeting at a heavy weight and slightly apart at the base of the boom. For a vertical like John Lahr showed previously, if the spring angle is brought more horizontal (parallel with the boom ) my understanding is the period is increased. I thought the same might apply with the horizontal and one would not have to worry as much about the drift the Lehman can produce as the boom assemble approaches the non returning position ( ie trying to increase the lehman period). Sorry I got so wordy Regards Barry. Kareem at HeyJooJoo wrote: Hi Steve, Are there any simple plans for building a horizontal, long period seismograph? (I know that there are tons of places online but figured you or the others may know of some real-time plans.) Kareem -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Steve Hammond Sent: Wednesday, February 22, 2006 9:02 AM To: psn-l@............... PSN-L@.............. Subject: RE: two home-made vertical seismometers If you want to build a simple seismograph, here is a URL of a very simple vertical seismograph that was designed by a fellow in Pasadena in the early 1990's. http://pw2.netcom.com/~shammon1/compressed/VERTICAL.GIF It uses a screen door spring and cost under $20. It is made from common parts in a local hardware store and produces good results. It does lack the electronics however, so if you check the same site, http://pw2.netcom.com/~shammon1/equip.htm#Electronics you will find a pre-amp using OP-07's that can be used with this. The coil can be built from #44 wire on a plastic frame. You can get the frame from Radio Shack if you just purchase a spool of their red/black/green #22 construction wire. Hand wind about 4,000 turns of the #44 wire onto a frame. Warp the coil in black electrical tape to protect it. The magnet is a cow magnet sold in an animal feed stores but other magnets will also work. I used these plans to build a system for a 5th grade classroom and the students were able to locate local events with it. Regards, Steve Hammond PSN San Jose, Aptos California -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Gerencher, Joseph J Sent: Tuesday, February 21, 2006 12:09 PM To: PSN-L@.............. Subject: two home-made vertical seismometers I have photographs of two vertical seismometers that were made by Jim Lehman and given to me. Both have been in continuous operation for several years and both have a natural period of about one second. The smaller unit is in my classroom and the larger one is in the basement beneath the classroom. I modified the damping of the smaller unit using copper plumbing fittings, which makes it both easier to construct and easier to operate than the larger one. The web address for going directly to the photographs is too long to post on an e-mail, so if you want to see images of both these seismometers go to my opening web page at http://home.moravian.edu/users/phys/mejjg01/ then click "homemade seismographs," click "Illustrated history of the seismometer system, 1991 to 1998" and click the links on that page. Additional detailed photographs of the construction design of the smaller home-made seismometer can be found at the following web site: http://www.netquake.org/seismometers/vertical.htm Unfortunately, I have not yet gotten around to annotating these photographs, but intend to do so in the next several days. Joe Gerencher __________________________________________________________ Public Seismic Network Mailing List (PSN-L) To leave this list email PSN-L-REQUEST@.............. with the body of the message (first line only): unsubscribe See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Recording Micro Quakes From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 24 Feb 2006 02:50:02 +0000 Hi Kareem I am using short period sensor, an 4.5Hz Geophone that i got from here, http://seismicnet.com/geophone/index.html#L15B This geophone has the range of 860 - 1000km (my estimate). Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Winquake command line From: Larry Conklin lconklin@............ Date: Fri, 24 Feb 2006 15:47:19 -0500 I know that if you select two compatible (ie. two files from the same event with the same header info, etc.) files from the file dialog box at the same time, that Winquake will open them together in a single window. Winquake will also open a single file specified as a command line argument. Is there a command line syntax that will open more than one file at once with a single command? I tried several plausible alternatives with no success. Larry Conklin __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Winquake command line From: Larry Cochrane lcochrane@.............. Date: Fri, 24 Feb 2006 19:28:01 -0800 Larry, WinQuake only processes one file on the command line so currently there is no way to open two or more event files. Regards, Larry Cochrane Redwood City, PSN Larry Conklin wrote: > I know that if you select two compatible (ie. two files from the same > event with the same header info, etc.) files from the file dialog box at > the same time, that Winquake will open them together in a single window. > Winquake will also open a single file specified as a command line > argument. Is there a command line syntax that will open more than one > file at once with a single command? I tried several plausible > alternatives with no success. > > Larry Conklin > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: The Canada earthquake, instresing location From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 25 Feb 2006 05:47:08 +0000 Hi all The Canada earthquake, that did happen at 01:39 tonight (UTC) (25th feb.2006) is at intresting location. See map here, http://www.emsc-csem.org/index.php?page=current&sub=detail&id=HM304;NEIR I do not know the earthquake history of this reagion. But i wonders if there is a possibliti for this to be a pre-earthquake for a maybe a bigger event. I do not know if there was some aftershocks from this event, i don't see any signs of it on the usgs webpage. Far as i know, there aren't any fault lines in this region, but my knowlage is lacking regarding this area in terms of geological features. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: The Canada earthquake, instresing location From: Canie canie@........... Date: Fri, 24 Feb 2006 22:08:08 -0800 Here's a page on it from USGS - talks of historic seismicity http://earthquake.usgs.gov/eqcenter/recenteqsww/Quakes/usjpad.php Canie At 09:47 PM 2/24/2006, you wrote: >Hi all > >The Canada earthquake, that did happen at 01:39 tonight (UTC) (25th >feb.2006) is at intresting location. See map here, >http://www.emsc-csem.org/index.php?page=3Dcurrent&sub=3Ddetail&id=3DHM304;N= EIR > >I do not know the earthquake history of this reagion. But i wonders if >there is a possibliti for this to be a pre-earthquake for a maybe a >bigger event. I do not know if there was some aftershocks from this >event, i don't see any signs of it on the usgs webpage. Far as i know, >there aren't any fault lines in this region, but my knowlage is lacking >regarding this area in terms of geological features. > >Regards. >-- >J=F3n Fr=EDmann J=F3nsson >http://www.jonfr.com >http://www.simnet.is/jonfr500/earthquake/ > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: The Canada earthquake, instresing location From: Dave Nelson davenn@............... Date: Sat, 25 Feb 2006 22:01:59 +1100 Hi Jon the nth american/canadian continent is very old and is heavily faulted and regular small to medium quakes are common including the occassional large event as the link that Carnie gave shows there is plent of activity in this= region one thing you will find is that many of the river channels ... eg the St Lawrence River follow faultlines as the rock along the=20 faultlines is softer and easily erroded this is a common feature along older landscapes and is a feature I=20 learnt to recognise quickly during my geological studies in new zealand the rivers of the tibetan plateau in the himilayan mountains in asia is= =20 a classic example of this feature cheers At 05:47 AM 2/25/2006 +0000, you wrote: >Hi all >I do not know the earthquake history of this reagion. But i wonders if >there is a possibliti for this to be a pre-earthquake for a maybe a >bigger event. I do not know if there was some aftershocks from this >event, i don't see any signs of it on the usgs webpage. Far as i know, >there aren't any fault lines in this region, but my knowlage is lacking >regarding this area in terms of geological features. >Regards. >J=F3n Fr=EDmann J=F3nsson Dave Nelson VK2TDN Sydney Australia www.sydneystormcity.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Winquake Ascii Text File From: "Geoffrey" gmvoeth@........... Date: Sat, 25 Feb 2006 22:54:38 -0700 Hello PSN: Could someone please send me a Winquake Ascii text file so I may check my conversion from a raw 8 bit format to Winquake ascii. This is what I think it should look like: ----------------START of File------------------ ! PSN ASCII Event File Format 1.0 Start Time: yyyy/dd/mm hh:mm:ss.s Number of Samples: nnnn SPS: 18.205556 Comment: A/D Converter Bits: Data Minimum: -127 Data Maximum: 128 ! Sensor Information: Sensor Location: Apache Junction, Arizona Sensor Latitude: 33.421380 Sensor Longitude: -111.574770 Sensor Orientation: Z ! Event Information: Event Latitude: Event Longitude: Event Time: Event Magnitude: Event Depth: ! WinQuake Information: Magnitude Correction: Mb Magnitude Correction: Ms Period: 20.000000 Mb Period: 1.000000 Md Duration: PS Pick Information: ! SDR Information: Lock Indicator: Data: -2 <------------- First Data Point -8 --------------END Of File-------------------- I am guessing those are minus signs in front of the two data points. I am not certain what the file extension should be or if I am missing something else. I am too cheap to buy Winquake at this time but I would like to be able to share my files with people who have this program. I understand only the first four lines are necessary. This text file is one I tried to convert: http://users.isp.com/gmvoethb293690/WQFIJI00.TXT If you have Winquake you can try it out and please tell me what happens. Regards; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Two earthquakes at the same time From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 28 Feb 2006 06:03:54 +0000 Hi all Yesterday i did record a earthquake at mag 3.07ML at 02:42 UTC. Today i was updateing the time and location with the final resault from the Icelandic met office regarding this earthquake when i did notice that where actually two earthquaks at that same time, happening with less then 1 sec (they where just less then 100ms apart in time) time diffrance. I problay did detect both of those earthquakes, but becose how close they are in time it is hard for me to tell what earthquake is what in the trace. This also leads to the fact the trace is a bit diffrence since there where two earthquakes almost at the same loaction at the same time. The trace is on the Psn event file list, the automatic location that i did use did give up the size 2.9ML. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Room Temp Super Conductor coil From: "Geoffrey" gmvoeth@........... Date: Wed, 1 Mar 2006 08:32:01 -0700 Would a room temperature superconductor make a good coil for coil-magnet seismic sensor ? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Does Anyone know how to get ahold of Larry From: "Geoffrey" gmvoeth@........... Date: Wed, 1 Mar 2006 09:59:46 -0700 I was interested in registering Winquake but when I sent a message to Larry this is what came back ************* See Below ************ This is the Postfix program at host mail13.mdx.safepages.com. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to If you do so, please include this problem report. You can delete your own text from the attached returned message. The Postfix program : host mail1.webtronics.com[66.92.4.80] said: 550 5.1.1 is not a valid mailbox (in reply to RCPT TO command) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Does Anyone know how to get ahold of Larry From: "Steve Hammond" shammon1@............. Date: Wed, 1 Mar 2006 10:08:45 -0800 He should see this. Steve Hammond -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Geoffrey Sent: Wednesday, March 01, 2006 9:00 AM To: PSN Subject: Does Anyone know how to get ahold of Larry I was interested in registering Winquake but when I sent a message to Larry this is what came back ************* See Below ************ This is the Postfix program at host mail13.mdx.safepages.com. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to If you do so, please include this problem report. You can delete your own text from the attached returned message. The Postfix program : host mail1.webtronics.com[66.92.4.80] said: 550 5.1.1 is not a valid mailbox (in reply to RCPT TO command) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Room Temp Super Conductor coil From: Ben Bradley benbradley@............... Date: Wed, 01 Mar 2006 13:13:50 -0500 Geoffrey wrote: > Would a room temperature superconductor make a good coil for coil-magnet > seismic sensor ? I don't see any advantage, as the coil resistance in a coil used for a seismic sensor is of little significance. The resistance may be fairly high due to the thin wire and large number of turns of the coil, but it's easy enough to make high-impedance circuitry to measure signal voltage without loading down the coil. > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Room Temp Super Conductor coil From: "Jack Ivey" ivey@.......... Date: Wed, 1 Mar 2006 13:39:40 -0500 The thermal noise produced by the resistance of the coil would go to zero, but it's unlikely that this is the primary source of noise in most seismometers. Jack > Would a room temperature superconductor make a good coil for coil-magnet=20 > seismic sensor ? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Room Temp Super Conductor coil From: ChrisAtUpw@....... Date: Wed, 1 Mar 2006 13:52:30 EST In a message dated 01/03/2006, ivey@.......... writes: The thermal noise produced by the resistance of the coil would go to zero, but it's unlikely that this is the primary source of noise in most seismometers. Hi there, Where do you get a room temperature superconductor? And what is it? Last time I looked they had critical temperatures just above liquid O2, 90 K. Coil / amplifier low noise combinations are designed on the coil resistance, so if this did go to zero, you would need to develop a different amplifier circuit - not use the same one. Regards, Chris Chapman

In a message dated 01/03/2006, ivey@.......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 thermal noise produced by the resistance of the coil would go to zero, but= =20 it's unlikely that this is the primary source of noise in most=20 seismometers.

Hi there,

Where do you get a room temperature superconduc= tor?=20 And what is it? Last time I looked they had critical temperatures just=20 above liquid O2, 90 K.

Coil / amplifier low noise combinations are=20 designed on the coil resistance, so if this did go to zero, you would need t= o=20 develop a different amplifier circuit - not use the same one.

Regards,

Chris Chapman

Subject: Re: Room Temp Super Conductor coil From: ChrisAtUpw@....... Date: Thu, 2 Mar 2006 08:09:18 EST In a message dated 01/03/2006, gmvoeth@........... writes: Would a room temperature superconductor make a good coil for coil-magnet seismic sensor ? The highest superconducting temperature to date is 138 K = -135 C See _http://www.superconductors.org/_ (http://www.superconductors.org/) There is still quite a long way to go before we get anywhere near room temperature. Regards, Chris Chapman

In a message dated 01/03/2006, gmvoeth@........... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Would a=20 room temperature superconductor make a good coil for coil-magnet seismic=20 sensor ?

The highest superconducting temperature to date= is=20 138 K =3D -135 C

See http://www.superconductors.org/= There=20 is still quite a long way to go before we get anywhere near room=20 temperature.

Regards,

Chris Chapman

Subject: STM's VBB equations From: Barry Lotz barry_lotz@............. Date: Thu, 2 Mar 2006 19:26:40 -0800 (PST) Hi All I have constructed 3 long period seismographs which used info from STM's web site. They work well. What isn't working well is duplicating STM's equation results for the sensors response. I have tried my DOS version of mathcad and have just created the equations in Excel. I get the same results with both. However they differ from that STM got and also Al Coleman. I have been able to duplicate most of their results except for the response slope at both ends of the velocity graph, especially at the low end. My graphs drop off too dramatically. Has anyone run the equations and duplicated STM's results with his seismograph characteristics? I am an engineer and understand equations. I suppose that I'm not reproducing some subtle portion of the equations, though I have stared at them for days. Regards Barry

Hi All

I have constructed 3 long period seismographs which used info from STM's web site. They work well. What isn't working well is duplicating STM's equation results for the sensors response. I have tried my DOS version of mathcad and have just created the equations in Excel. I get the same results with both. However they differ from that STM got and also Al Coleman. I have been able to duplicate most of their results except for the response slope at both ends of the velocity graph, especially at the low end. My graphs drop off too dramatically. Has anyone run the equations and duplicated STM's results with his seismograph characteristics? I am an engineer and understand equations. I suppose that I'm not reproducing some subtle portion of the equations, though I have stared at them for days.

Regards

Barry

Subject: Re: STM's VBB equations From: Brett Nordgren Brett3kg@............. Date: Fri, 03 Mar 2006 07:37:07 -0500 Barry, If you haven't already, you may want to look at some of my data on http://bnordgren.org/seismo/ In particular, the files 'loop3.pdf', 'lpmeas2.pdf', and probably some others. If you can provide some more details, I'll be happy to try to help. Regards Brett At 07:26 PM 3/2/2006 -0800, you wrote: >Hi All > I have constructed 3 long period seismographs which used info from > STM's web site. They work well. What isn't working well is duplicating > STM's equation results for the sensors response. I have tried my DOS > version of mathcad and have just created the equations in Excel. I get > the same results with both. However they differ from that STM got and > also Al Coleman. I have been able to duplicate most of their results > except for the response slope at both ends of the velocity graph, > especially at the low end. My graphs drop off too dramatically. Has > anyone run the equations and duplicated STM's results with his > seismograph characteristics? I am an engineer and understand equations. I > suppose that I'm not reproducing some subtle portion of the equations, > though I have stared at them for days. >Regards >Barry > If my e-mail address above is not working you can always reach my mail form at: http://bnordgren.org/contactB.html using your Web browser. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: STM's VBB equations From: Brett Nordgren Brett3kg@............. Date: Fri, 03 Mar 2006 08:27:16 -0500 Barry, I see now that there is a newer version of the 'loop' pdf that's not shown in the index. It corrects some errors, adds some clarifications and has some notes to myself about what more needs to be worked on. http://bnordgren.org/seismo/loop4.pdf is probably a better one to use. Regards Brett __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: My Online seismographs are offline for the next 24 hours, computer From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 06 Mar 2006 14:01:21 +0000 Hi all My online seismogrpahs are not going to update in the next 24 hours becose of a computer failure. I had planned to change about hard drive in the computer that work out the data from the geophone. However i did suffer psu failure when i was changeing about the hard drive.I am going to try to run winsdr in linux with wine API software in order to continue recording earthquakes, but i won't update the online graphs in such low level user mode. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: speaking about bad luck From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 06 Mar 2006 15:52:06 +0000 Hi all I had a really bad luck today. As i told you in my email early today i had a psu failure in the computer that records earthquakes for me. But also today there was a earthquake that was 4.5Mb on the Reykjanes ridge, it was felt in Reykjavik. More info here, http://www.emsc-csem.org/index.php?page=current&sub=detail&id=HP408;2006 But becose my earthquake computer is down i didn't record this earthquake. :( I really hate it when something like this happens. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: My Online seismographs are offline for the next 24 hours, computer hardwa... From: ChrisAtUpw@....... Date: Mon, 6 Mar 2006 21:47:56 EST In a message dated 06/03/2006, jonfr500@......... writes: However i did suffer psu failure when i was changeing about the hard drive. Hi Jon, Look inside the PSU case, opening one side if necessary. They very often have a fuse on the circuit board that they don't tell you about! Regards, Chris Chapman

In a message dated 06/03/2006, jonfr500@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>However=20 i did
suffer psu failure when i was changeing about the hard=20 drive.

Hi Jon,

Look inside the PSU case, opening one side if=20 necessary. They very often have a fuse on the circuit board that they don= 't=20 tell you about!

Regards,

Chris Chapman

Subject: Re: My Online seismographs are offline for the next 24 hours, From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 07 Mar 2006 16:10:01 +0000 Hi Chris The psu did work agen this morning when i did test it. I didn't get new psu today as expected, that is why i did test the psu that did fail yesterday. I also did discover a problem with the new hard drive, i found out that it wasn't so new as the store who sold it ment it to be. I did send them the hard drive back and i will get new one after few days. I am going to get new psu tomorrow and i expect the change to with out a problem, one can only hope. I did try to open the psu box, but i didn't find any clear way to open the box. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: WinSDR crashing on single line display From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 11 Mar 2006 00:25:53 +0000 Hi all In my computer the winSDR computer has the issue of crashing when i try to use the single line display feature. Why this happens is unkown to me, but i want to see if anyone else that is using Winsdr has this problem. I don't think this is a memory releated problem, since i am not haveing problem with other software or Windows 2000. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: line driver question From: Barry Lotz barry_lotz@............. Date: Tue, 14 Mar 2006 20:59:58 -0800 (PST) Hi All I was planning to put a line driver on the position voltage output of my vbb style sensor. Currently I run it directly about 40' to my house but I think it affects the triple feedback circuit. The simple way is to put a non-inverting follower at the circuit output. The question is (lets see if I can explain this) the non-inverting opamp on the velocity output of the sensor has a small resistor between the output of the opamp (~10 ohms) and the line going back to the negative opamp input and a small (pf) capacitor between the opamp output and the negative input . I think this is for damping high frequency oscillations. Should I use this with the unity gain follower? I'm not sure if its necessary or how to do this. The only way I can think of is to put a high resistor (~100k) before the positive opamp input and a 100k in the line going back to the negative input and then put the small cap and resistor as noted above. I'm not sure that this will acomplish anything. I didn't want to have a voltage divider before the non inverting opamp to reduce the voltage in half and then have a 2X noninverting opamp line driver. I think the voltage divider will affect the current flow to my feedback coil. Regards Barry

Hi All

I was planning to put a line driver on the position voltage output of my vbb style sensor. Currently I run it directly about 40' to my house but I think it affects the triple feedback circuit. The simple way is to put a non-inverting follower at the circuit output. The question is (lets see if I can explain this) the non-inverting opamp on the velocity output of the sensor has a small resistor between the output of the opamp (~10 ohms) and the line going back to the negative opamp input and a small (pf) capacitor between the opamp output and the negative input . I think this is for damping high frequency oscillations. Should I use this with the unity gain follower? I'm not sure if its necessary or how to do this. The only way I can think of is to put a high resistor (~100k) before the positive opamp input and a 100k in the line going back to the negative input and then put the small cap and resistor as noted above. I'm not sure that this will acomplish anything.

I didn't want to have a voltage divider before the non inverting opamp to reduce the voltage in half and then have a 2X noninverting opamp line driver. I think the voltage divider will affect the current flow to my feedback coil.

Regards

Barry

Subject: Re: line driver question From: John Popelish jpopelish@........ Date: Wed, 15 Mar 2006 00:26:18 -0500 Barry Lotz wrote: > Hi All > I was planning to put a line driver on the position voltage > output of my vbb style sensor. Currently I run it directly > about 40' to my house but I think it affects the triple feedback > circuit. The simple way is to put a non-inverting follower > at the circuit output. The simple way to accomplish what? > The question is (lets see if I can explain this) > the non-inverting opamp on the velocity output of the sensor > has a small resistor between the output of the opamp (~10 ohms) > and the line going back to the negative opamp input > and a small (pf) capacitor between the opamp output > and the negative input. I think this is for damping high frequency > oscillations. It improves the opamps stability in the presence of a capacitive load, like long wiring has. I seldom see this between opamps on the same board. > Should I use this with the unity gain follower? It probably can't hurt. But I don't understand the purpose of the follower, to begin with. > I'm not sure if its necessary or how to do this. > The only way I can think of is to put a high resistor (~100k) > before the positive opamp input and a 100k in the line going > back to the negative input and then put the small cap and resistor > as noted above. The input resistor in the + input leg is necessary, only if the bias current error of the opamp is significant to you. Some opamps have such low bias current that the drop across the 100k feedback resistor is less than the offset voltage of the input. > I'm not sure that this will acomplish anything. You may be solving a non problem. Will this follower drive a long wire? > I didn't want to have a voltage divider before the > non inverting opamp to reduce the voltage in half and then have > a 2X noninverting opamp line driver. I agree that this is not the way to go, if it can be avoided. > I think the voltage divider will affect the current flow > to my feedback coil. It will not improve the accuracy of the follower. But, if this opamp drives a feedback current, how 'bout configuring it as a voltage controlled current source, so that wiring resistance will have little effect on the accuracy? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: line driver question From: "Geoffrey" gmvoeth@........... Date: Wed, 15 Mar 2006 05:39:51 -0700 > It will not improve the accuracy of the follower. But, if this opamp > drives a feedback current, how 'bout configuring it as a voltage > controlled current source, so that wiring resistance will have little > effect on the accuracy? Are you talking about something like they use in industry and telephone called a 20 milliamp loop ? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: line driver question From: John Popelish jpopelish@........ Date: Wed, 15 Mar 2006 10:09:37 -0500 Geoffrey wrote: > >> It will not improve the accuracy of the follower. But, if this opamp >> drives a feedback current, how 'bout configuring it as a voltage >> controlled current source, so that wiring resistance will have little >> effect on the accuracy? > > > > Are you talking about something like they use in industry > and telephone called a 20 milliamp loop ? Something like, yes, in that it is a circuit that regulates current, rather than voltage. However, the teletype 20 mA loop had only two output values, 0 and 20 mA, and was often only crudely regulated (sometimes just with a big series resistor and a high voltage power supply). Voltage negative feedback (feedback from the output that is proportional to the output voltage) tends to lower the output impedance of an amplifier. That is, it tends to make the output voltage almost independent of the load current. But if the negative feedback is proportional to the load current, instead of output voltage, it tends to raise the output impedance, and make it almost independent of the voltage. Add resistance (wiring) in series with the load,m and the output voltage increases to compensate and keep the current as intended. This works well only at frequencies below those where the wiring acts as a capacitive load that rolls off the high frequencies, so there are limits to how fast the current at the far end of a wire can be regulated. But at 40 feet of length, it is probably high enough. Whether or not a current regulator is a better idea than a voltage regulator output, in this application, depends on details I don't have in front of me. If accurate voltage at a distance is needed, a feedback pair of wires that act as long volt meter leads that return the voltage feedback from the load are another possibility for improving accuracy. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: line driver question From: Brett Nordgren Brett3kg@............. Date: Wed, 15 Mar 2006 10:17:33 -0500 Hi Barry, At 08:59 PM 3/14/2006 -0800, you wrote: >Hi All > I was planning to put a line driver on the position voltage output of my > vbb style sensor. Currently I run it directly about 40' to my house but I > think it affects the triple feedback circuit. That is possible, though not certain. I think that the position ouput comes off from the capacitor of the integrator branch, putting the cable capacitance in parallel with the relatively large integrator capacitor. Adding a few (hundred) pf of cable capacitance to that, shouldn't affect things much, unless the loop is already close to oscillating. Small amounts of DC introduced back into the cable or resistive loading would be a more serious problem. >The simple way is to put a non-inverting follower at the circuit output. >The question is (lets see if I can explain this) the non-inverting opamp >on the velocity output of the sensor has a small resistor between the >output of the opamp (~10 ohms) and the line going back to the negative >opamp input and a small (pf) capacitor between the opamp output and the >negative input . I think this is for damping high frequency oscillations. The RC was possibly a trial and error solution to kill a high frequency oscillation. A good analysis of why the loop was oscillating in the first place might suggest some better solution for that issue. >Should I use this with the unity gain follower? I'm not sure if its >necessary or how to do this. The only way I can think of is to put a high >resistor (~100k) before the positive opamp input and a 100k in the line >going back to the negative input and then put the small cap and resistor >as noted above. I'm not sure that this will acomplish anything. A unity gain follower couldn't hurt and would isolate the signal path from AC and DC leakage feeding back into it from the cable and load circuits. Input signal from the integrator capacitor goes to the plus op amp input, negative input connects to its output which also drives the cable. You might want to add 1k or so in series between the op amp output and cable input end to reduce the danger to the op amp from accidental shorts or voltage transients fed back through the cable. At the low frequencies involved, the added resistance shouldn't have much of an effect. >I didn't want to have a voltage divider before the non inverting opamp to >reduce the voltage in half and then have a 2X noninverting opamp line >driver. I think the voltage divider will affect the current flow to my >feedback coil. >Regards >Barry It would help if I could see the circuit. Is there an image file available? The circuit in my head may be far from what you have. Regards, Brett If my e-mail address above is not working you can always reach my mail form at: http://bnordgren.org/contactB.html using your Web browser. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: line driver question From: Richard Gagnon richg_1998@......... Date: Wed, 15 Mar 2006 07:27:00 -0800 (PST) > Something like, yes, in that it is a circuit that regulates current, > rather than voltage. However, the teletype 20 mA loop had only two > output values, 0 and 20 mA, and was often only crudely regulated > (sometimes just with a big series resistor and a high voltage power > supply). I work in industry in the USA that uses 20ma and it is 4ma to 20ma with regulated power supplies. The signal can be any value between those two numbers, quite often 0 signal is 4ma and maximum signal is 20ma. Machine computer control is very effective at sending the exact values via a d/a module. This may have nothing to do with this thread but I wanted to comment on the technology. Cheers Richard __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: line driver question From: John Popelish jpopelish@........ Date: Wed, 15 Mar 2006 10:44:54 -0500 Richard Gagnon wrote: > I work in industry So do I. :-) > in the USA that uses 20ma and it is 4ma to 20ma with > regulated power supplies. The signal can be any value between those two > numbers, quite often 0 signal is 4ma and maximum signal is 20ma. Machine > computer control is very effective at sending the exact values via a d/a > module. > This may have nothing to do with this thread but I wanted to comment on the > technology. Yes, that is the analog extension of the old digital 20 mA teletype current loop. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Moonquakes, intresting artical by nasa From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Thu, 16 Mar 2006 04:03:01 +0000 Hi all I want to point out this artical from nasa about moonquakes. http://science.nasa.gov/headlines/y2006/15mar_moonquakes.htm?list131101 Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Moonquakes, intresting artical by nasa From: "Geoffrey" gmvoeth@........... Date: Wed, 15 Mar 2006 21:43:31 -0700 If you look hard enough you should also be able to find a design that they are considering for use on MARS. It is a capacitive sensor I think with an X/Y motion mass suspended by a series of leaf springs. It looks like it would be great for amateurs if only could get our hands on such a thing. They are putting considerable time and effort or so it seems into making a light weight seismometer that would be very portable. I can not remember where I saw the design but they had a photo of the guts to the thing. I have always thought it would be nice to have a seismometer you could easily move from one place to another. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: line driver question From: Barry Lotz barry_lotz@............. Date: Wed, 15 Mar 2006 20:45:50 -0800 (PST) John,Brett,Richard&Geoffrey Thanks for the "feedback" :). All I am trying to do is monitor a voltage in a feedback circuit from 40' from the circuit without affecting the performance of the feedback circuit. The monitored voltage goes to a LCD voltage display in my house.I think I will just try a follower with a resistor at the output , to prevent transient voltages from entering the feedback circuit from the shielded line. regards Barry

John,Brett,Richard&Geoffrey

Thanks for the "feedback" :). All I am trying to do is monitor a voltage in a feedback circuit from 40' from the circuit without affecting the performance of the feedback circuit. The monitored voltage goes to a LCD voltage display in my house.I think I will just try a follower with a resistor at the output , to prevent transient voltages from entering the feedback circuit from the shielded line.
regards

Barry

Subject: RE: line driver question From: "Keith Payea" kpayea@........... Date: Wed, 15 Mar 2006 21:12:12 -0800 Barry: The circuit you describe is the classic way to deal with a large capacitive load on an op-amp. The series resistor decouples the capacitance from the op-amp output, and the local feedback capacitor keeps the whole thing stable. There are also op-amps which are designed to drive highly capacitive loads like this. It's not so critical if you don't need high gain in addition to the line driving capability. I use a part called the LM837 in my VBB output to drive the 70 or 80 feet of cable back to the SDR system. See the schematic at: http://www.bryantlabs.net/Images/SenseAmp.pdf You can see I have a small resistor in series with the output also. You are right to add a buffer between the internal "Analog Computer" and the cable. I agree the issue is not so much the added capacitance as the potential to feed noise into the process back up the cable. Opamps are cheap... Cheers, Keith _____ From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Barry Lotz Sent: Wednesday, March 15, 2006 8:46 PM To: psn-l@.............. Subject: Re: line driver question John,Brett,Richard&Geoffrey Thanks for the "feedback" :). All I am trying to do is monitor a voltage in a feedback circuit from 40' from the circuit without affecting the performance of the feedback circuit. The monitored voltage goes to a LCD voltage display in my house.I think I will just try a follower with a resistor at the output , to prevent transient voltages from entering the feedback circuit from the shielded line. regards Barry

Barry:

The circuit you describe is the classic way to = deal with a=20 large capacitive load on an op-amp. The series resistor decouples = the=20 capacitance from the op-amp output, and the local feedback capacitor = keeps the=20 whole thing stable. There are also op-amps which are designed to = drive=20 highly capacitive loads like this. It's not so critical if you = don't need=20 high gain in addition to the line driving = capability.

I use a part called the LM837 in my VBB output = to drive the=20 70 or 80 feet of cable back to the SDR system. See the schematic = at: http://www.bryantl= abs.net/Images/SenseAmp.pdf =20 You can see I have a small resistor in series with the output=20 also.

You are right to add a buffer between the = internal "Analog=20 Computer" and the cable. I agree the issue is not so much the = added=20 capacitance as the potential to feed noise into the process back up the=20 cable. Opamps are cheap...

Cheers,

Keith

From: psn-l-request@................. [mailto:psn-l-request@............... On Behalf Of Barry=20 Lotz
Sent: Wednesday, March 15, 2006 8:46 PM
To:=20 psn-l@..............
Subject: Re: line driver=20 question

John,Brett,Richard&Geoffrey

Thanks for the "feedback" :). All I am trying to do is = monitor a=20 voltage in a feedback circuit from 40' from the circuit = without=20 affecting the performance of the feedback circuit. The monitored voltage = goes to=20 a LCD voltage display in my house.I think I will just try a follower = with a=20 resistor at the output , to prevent transient voltages from = entering the=20 feedback circuit from the shielded line.
regards

Barry

Subject: Op Amp circuits From: Brett Nordgren Brett3kg@............. Date: Thu, 16 Mar 2006 08:24:03 -0500 Barry, In looking around for op-amp information, I just ran across the excellent TI application note below. http://focus.ti.com/lit/an/sboa092a/sboa092a.pdf It has 93 pages of op-amp circuits and information on how to design with them. Hope you or someone else here may find it useful. Regards, Brett __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: line driver question From: "Steve Hammond" shammon1@............. Date: Thu, 16 Mar 2006 08:07:53 -0800 Hi Berry, you might send this question to TJ Byers at tjbyers@....... . He writes the Q&A column in Nuts&Volts. He likes unusual questions. Steve Hammond -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Barry Lotz Sent: Wednesday, March 15, 2006 8:46 PM To: psn-l@.............. Subject: Re: line driver question John,Brett,Richard&Geoffrey Thanks for the "feedback" :). All I am trying to do is monitor a voltage in a feedback circuit from 40' from the circuit without affecting the performance of the feedback circuit. The monitored voltage goes to a LCD voltage display in my house.I think I will just try a follower with a resistor at the output , to prevent transient voltages from entering the feedback circuit from the shielded line. regards Barry

Hi=20 Berry, you might send this question to TJ Byers at tjbyers@....... . He writes the = Q&A column=20 in Nuts&Volts. He likes unusual questions.

Steve=20 Hammond

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of Barry=20 Lotz
Sent: Wednesday, March 15, 2006 8:46 PM
To:=20 psn-l@..............
Subject: Re: line driver=20 question

John,Brett,Richard&Geoffrey

Thanks for the "feedback" :). All I am trying to do is = monitor a=20 voltage in a feedback circuit from 40' from the circuit = without=20 affecting the performance of the feedback circuit. The monitored = voltage goes=20 to a LCD voltage display in my house.I think I will just try a = follower with a=20 resistor at the output , to prevent transient voltages from = entering the=20 feedback circuit from the shielded line.
regards

Barry

Subject: RE: line driver question From: "Steve Hammond" shammon1@............. Date: Thu, 16 Mar 2006 08:10:47 -0800 Ops... Sorry Barry-- (Not Berry) It's early and I'm still on coffee #1. S-- -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Steve Hammond Sent: Thursday, March 16, 2006 8:08 AM To: psn-l@.............. Subject: RE: line driver question Hi Berry, you might send this question to TJ Byers at tjbyers@....... . He writes the Q&A column in Nuts&Volts. He likes unusual questions. Steve Hammond -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Barry Lotz Sent: Wednesday, March 15, 2006 8:46 PM To: psn-l@.............. Subject: Re: line driver question John,Brett,Richard&Geoffrey Thanks for the "feedback" :). All I am trying to do is monitor a voltage in a feedback circuit from 40' from the circuit without affecting the performance of the feedback circuit. The monitored voltage goes to a LCD voltage display in my house.I think I will just try a follower with a resistor at the output , to prevent transient voltages from entering the feedback circuit from the shielded line. regards Barry

Ops...=20 Sorry Barry-- (Not Berry) It's early and I'm still on coffee=20 #1.

S--

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of Steve=20 Hammond
Sent: Thursday, March 16, 2006 8:08 AM
To: = psn-l@..............
Subject: RE: line driver=20 question

Hi=20 Berry, you might send this question to TJ Byers at tjbyers@....... . He writes the = Q&A=20 column in Nuts&Volts. He likes unusual = questions.

Steve Hammond

-----Original Message-----
From:=20 psn-l-request@.............. = [mailto:psn-l-request@...............On=20 Behalf Of Barry Lotz
Sent: Wednesday, March 15, 2006 = 8:46=20 PM
To: psn-l@..............
Subject: Re: line = driver=20 question

John,Brett,Richard&Geoffrey

Thanks for the "feedback" :). All I am trying to do is = monitor a=20 voltage in a feedback circuit from 40' from the circuit = without=20 affecting the performance of the feedback circuit. The monitored = voltage=20 goes to a LCD voltage display in my house.I think I will just try a = follower=20 with a resistor at the output , to prevent transient voltages = from=20 entering the feedback circuit from the shielded = line.
regards

Barry

Subject: RE: line driver question From: Barry Lotz barry_lotz@............. Date: Thu, 16 Mar 2006 20:05:04 -0800 (PST) Hi Steve Ah Nuts & Volts! I have about ten years worth. I didn't think of that. I like their new magazine format. I recommend it to all. Regards Barry Steve Hammond wrote: Hi Berry, you might send this question to TJ Byers at tjbyers@....... . He writes the Q&A column in Nuts&Volts. He likes unusual questions. Steve Hammond

Hi Steve

Ah Nuts & Volts! I have about ten years worth. I didn't think of that. I like their new magazine format. I recommend it to all.

Regards

Barry

Steve Hammond <shammon1@ix.netcom.com> wrote:

Hi Berry, you might send this question to TJ Byers at tjbyers@aol.com . He writes the Q&A column in Nuts&Volts. He likes unusual questions.

Steve Hammond

Subject: Long period seismonitor sensitivite ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 17 Mar 2006 17:28:02 +0000 Hi all With long period seismonitor what is the smallest earthquake that can be detected with such seismonitor ? Then i mean in teleseismic earthquake range. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Drum recorders From: "Steve Hammond" shammon1@............. Date: Fri, 17 Mar 2006 10:49:05 -0800 I have two 75-100 lbs. drum recorders that I have been given over the years. I would like to pass them on to somebody on the PSN list. They both need ink pen / supply tanks. I live in the Santa Cruz area. If you are interested, please send my a note off-line. Regards, Steve Hammond PSN San Jose, Aptos, CA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Long period seismonitor sensitivite ? From: Angel sismos@.............. Date: Fri, 17 Mar 2006 20:06:10 +0000 Hello J�n, Take a look at this page, it might help answer your question. http://jclahr.com/science/psn/magnitude.html Angel Friday, March 17, 2006, 5:28:02 PM, you wrote: > Hi all > With long period seismonitor what is the smallest earthquake that can be > detected with such seismonitor ? Then i mean in teleseismic earthquake > range. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Drum recorders From: Tamati chief.cook.nz@............ Date: Sat, 18 Mar 2006 09:05:01 +1300 TAMATI's WORD's OF WISDOM FOR THE GOOD OF ALL MANKIND HTTP://LIVE-PLANET.BLOGSPOT.COM http://www.webspawner.com/users/chiefcooknz/index.html Please give me feed back on what you think chief.cook.nz.@............ NZ-021-150-33-59 or NZ-07-855-0195 Hi What a b*((*&^ that I'm in NZ grrrrrrr'a but that's the brakes, no-cash to pay frieght that a bigger GRRRRRRRR'A Cheers Tamati From the Castle of Tamati, Hinemoa and Karauwa the Dog From the Castle of Tom, Robyn and the Dog I'm Just a Stone's Throw Away:- NZ-021-150-33-59 or NZ-07-855-0195 Bush Telegragh:- = chief.cook.nz@............ My Regular Pitstop:- Tamati = P.O.BOX 19-356 CENTRAL = HAMILTON NEW = ZEALAND ----- Original Message -----=20 From: "Steve Hammond" To: Sent: Saturday, March 18, 2006 7:49 AM Subject: Drum recorders >I have two 75-100 lbs. drum recorders that I have been given over the = years. > I would like to pass them on to somebody on the PSN list. They both = need ink > pen / supply tanks. I live in the Santa Cruz area. If you are = interested, > please send my a note off-line. > Regards, Steve Hammond PSN San Jose, Aptos, CA >=20 > __________________________________________________________ >=20 > Public Seismic Network Mailing List (PSN-L) >=20 > To leave this list email PSN-L-REQUEST@.............. with=20 > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information.

What a b*((*&^ that I'm in = NZ =20 grrrrrrr'a

but that's the brakes, no-cash to pay = frieght=20 that a bigger GRRRRRRRR'A

Cheers Tamati
From the Castle of = Tamati,=20 Hinemoa and Karauwa the Dog
From the Castle of Tom, Robyn and the=20 Dog

I'm Just a Stone's Throw Away:- = NZ-021-150-33-59=20 or=20 NZ-07-855-0195
         &= nbsp;           &n= bsp;       =20 Bush Telegragh:- chief.cook.nz@............
=          &nbs= p;            = ;=20 My Regular Pitstop:-=20 Tamati
          &nb= sp;           &nbs= p;            = ;            =             &= nbsp;     =20 P.O.BOX 19-356=20 CENTRAL
          &n= bsp;           &nb= sp;           &nbs= p;            = ;            =       =20 HAMILTON
          &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;      =20 NEW ZEALAND

----- Original Message ----- =

From: "Steve Hammond" = <shammon1@.............>

To: <psn-l@..............>

Sent: Saturday, March 18, 2006 7:49=20 AM

Subject: Drum=20 recorders

>I have two 75-100 lbs. drum recorders that I have = been given=20 over the years.
> I would like to pass them on to somebody on the = PSN=20 list. They both need ink
> pen / supply tanks. I live in the Santa = Cruz=20 area. If you are interested,
> please send my a note = off-line.
>=20 Regards, Steve Hammond PSN San Jose, Aptos, CA
>
>=20 __________________________________________________________
> =
>=20 Public Seismic Network Mailing List (PSN-L)
>
> To leave = this list=20 email PSN-L-REQUEST@.............. with
> the body of the message (first line only): = unsubscribe
> See http://www.seismicnet.com/maillist.html for more information. Subject: Detecting small earthquakes, update From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 18 Mar 2006 00:54:00 +0000 Hi all I have now been able to detect earthquakes down to 1.2ML at ~94 Km. I did also record a 1.6ML earthquake at 82Km the other day. Yesterday i did record a 2.47ML (clear) earthquake at 150Km, i did also record two other earthquakes yesterday that where 1.5ML and 1.6ML at ~150Km range but the signal that i got was poor. I did submitt those recordings to the psn list, becose the automatic system that Icelandic Met Office has did register both of those earthquakes as 2.1ML in size. I don't submit earthquakes smaller then 2.0ML in size to the psn event file list, becose it is really hard to see if there actually is a earthquake in the signal when earthquakes are that small, also the fact that i am about ~80Km away from the closest active seismitic zone here in Iceland, both South of my location, West of my location and North-East of my location. I am unsure of this, but i don't think WinSDR is desinged to detect this small earthquakes. I have to manual register those earthquakes. But it might also be that i have the noise setting so high that it doesn't detect that small earthquakes automatic. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Drum recorders From: "Kareem at HeyJooJoo" system98765@............. Date: Fri, 17 Mar 2006 18:30:27 -0800 Hi Steve, I'm interested but how do we get a hold of you off line? Contact me via my website: http://www.heyjoojoo.com/contact/feedback.php Kareem El Sobrante (The Leftovers), Ca -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Steve Hammond Sent: Friday, March 17, 2006 10:49 AM To: psn-l@.............. Subject: Drum recorders I have two 75-100 lbs. drum recorders that I have been given over the years. I would like to pass them on to somebody on the PSN list. They both need ink pen / supply tanks. I live in the Santa Cruz area. If you are interested, please send my a note off-line. Regards, Steve Hammond PSN San Jose, Aptos, CA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Long period seismonitor sensitivity ? From: ChrisAtUpw@....... Date: Fri, 17 Mar 2006 22:56:18 EST In a message dated 17/03/2006, jonfr500@......... writes: With a long period seismometer what is the smallest earthquake that can be detected with such a seismometer? I mean in the teleseismic earthquake range. Hi Jon, It depends on your instrument characteristics, the intrinsic equipment noise and on the local ambient seismic noise levels. For a system using 4.5 Hz geophones without period extension, you are likely to be frequency limited to local and near regional quakes, less than 6 deg, maybe quite a lot less. If you can detect 1.0, 0.5 Hz and longer period events either with different instruments or with low frequency period extension, you should be able to detect M6 quakes worldwide, but how much smaller will depend on the range of the quake and on your local noise, which is weather, environment and time related. Some data for an AS-1 can be found at _http://www2.bc.edu/~kafka/SeismoEd_SRL/kr03_page1.html_ (http://www2.bc.edu/~kafka/SeismoEd_SRL/kr03_page1.html) See page 6. I would expect a good quality Lehman or SG seismometer with a period of 20 sec to do better than this - the long period waves are of greater amplitude and the noise is likely to be less. Regional quakes are defined as being from 6 to 16 deg and teleseismic from 16 to 180 deg. There are several regions in the teleseismic range which have different characteristic and many different paths possible Regards, Chris Chapman

In a message dated 17/03/2006, jonfr500@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>With a=20 long period seismometer what is the smallest earthquake that can=20 be
detected with such a seismometer? I mean in the teleseismic earthqua= ke=20 range.

Hi Jon,

It depends on your instrument characteristics,=20= the=20 intrinsic equipment noise and on the local ambient seismic noise levels= ..=20 For a system using 4.5 Hz geophones without period extension, you are=20 likely to be frequency limited to local and near regional quakes, less than=20= 6=20 deg, maybe quite a lot less. If you can detect 1.0, 0.5 Hz and longer period= =20 events either with different instruments or with low frequency period extens= ion,=20 you should be able to detect M6 quakes worldwide, but how much smaller will=20 depend on the range of the quake and on your local noise, which is weather,=20 environment and time related.

Some data for an AS-1 can be found at http://www2.= bc.edu/~kafka/SeismoEd_SRL/kr03_page1.html =20 See page 6. I would expect a good quality Lehman or SG seismometer with a pe= riod=20 of 20 sec to do better than this - the long period waves are of greater=20 amplitude and the noise is likely to be less. Regional quakes are defined as= =20 being from 6 to 16 deg and teleseismic from 16 to 180 deg. There are several= =20 regions in the teleseismic range which have different characteristic and man= y=20 different paths possible

Regards,

Chris Chapman

Subject: Re: Long period seismonitor sensitivity ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sat, 18 Mar 2006 15:22:54 +0000 Hi Chris Thanks for that info. I plan in the future to build two long period seismonitors, one that is 1Hz and other that is 0.1Hz (SG seismonitor, if possible) to monitor teleseimic earthquakes. With my current hardware i can detect most regonal earthquakes that are 4.5Mb or larger along with local earthquakes that i detect alot of. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Long period seismonitor sensitivite ? From: Barry Lotz barry_lotz@............. Date: Sat, 18 Mar 2006 07:37:48 -0800 (PST) Hi Jon S-T Morrissey sent PSN an email on 13 nov 1999 which had an equation relating magnitude,amplitude, period and distance. I made a log-log plot of this, the x-axis was distance (km) the y-axis was counts. Each line was one magnitude. It was then interesting to plot my events on this sheet to see how they co-related. The problem I see is one of sensor gain and a/d converter. If you increase the gain to get more distant events then you clip a larger event that may come. I think a higher count a/d with lower gain would give a larger event magnitude range but I'm not sure where the noise begins to enter the picture. this will depent on the electronics & site. regards Barry regards Barry J�n Fr�mann wrote: Hi all With long period seismonitor what is the smallest earthquake that can be detected with such seismonitor ? Then i mean in teleseismic earthquake range. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________

Hi Jon

S-T Morrissey sent PSN an email on 13 nov 1999 which had an equation relating magnitude,amplitude, period and distance. I made a log-log plot of this, the x-axis was distance (km) the y-axis was counts. Each line was one magnitude. It was then interesting to plot my events on this sheet to see how they co-related. The problem I see is one of sensor gain and a/d converter. If you increase the gain to get more distant events then you clip a larger event that may come. I think a higher count a/d with lower gain would give a larger event magnitude range but I'm not sure where the noise begins to enter the picture. this will depent on the electronics & site.

regards

Barry

regards

Barry

J�n Fr�mann <jonfr500@.........> wrote:

Hi all

With long period seismonitor what is the smallest earthquake that can be
detected with such seismonitor ? Then i mean in teleseismic earthquake
range.

Regards.
--
J�n Fr�mann J�nsson
http://www.jonfr.com
http://www.simnet.is/jonfr500/earthquake/

__________________________________________________________

Subject: RE: Drum recorders From: "Steve Hammond" shammon1@............. Date: Sat, 18 Mar 2006 09:35:43 -0800 Hi Kareem, I'll talk photos today and send them to you and Paul in Colorado. Let's take this off-line, you can contact me at shammon1@.............. To the members, I have two people that have contacted me for the drums. If they are not taken I'll send another note to the list. Thanks, Steve Hammond -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Kareem at HeyJooJoo Sent: Friday, March 17, 2006 6:30 PM To: psn-l@.............. Subject: RE: Drum recorders Hi Steve, I'm interested but how do we get a hold of you off line? Contact me via my website: http://www.heyjoojoo.com/contact/feedback.php Kareem El Sobrante (The Leftovers), Ca -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Steve Hammond Sent: Friday, March 17, 2006 10:49 AM To: psn-l@.............. Subject: Drum recorders I have two 75-100 lbs. drum recorders that I have been given over the years. I would like to pass them on to somebody on the PSN list. They both need ink pen / supply tanks. I live in the Santa Cruz area. If you are interested, please send my a note off-line. Regards, Steve Hammond PSN San Jose, Aptos, CA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re[2]: Long period seismonitor sensitivity ? From: Angel sismos@.............. Date: Sun, 19 Mar 2006 13:47:03 +0000 Hello J�n, I have been following your progress in Iceland with interest, thanks for all of the information. I see that you mention that you want to build some long period devices and I would to invite you (and anyone else) to the FMES list. We have not been too active but the FMES (Fluid Mass Electolytic Seismograph) is very easy to build and is good from about 5 hz to 50 seconds. It has no moving parts except the fluid, which is water, anti-freeze and a foam reducer. You can join the list at http://groups.yahoo.com/group/fmes/ You can see some of the traces of different FMESes at http://64.116.183.133/FMES/welcome.html http://64.116.183.133/welcome.html http://www.regioweer.info/seismo.php two of those are mine and the other belongs to Marchal Dave, Chris, Marchal and myself have working systems and I plan to build more, we would welcome other to make some of these device so that we can learn more faster and have more ideas come to all of use. As the Perl perople say, "There is more than one way to do it" regards, Angel Saturday, March 18, 2006, 3:22:54 PM, you wrote: > Hi Chris > Thanks for that info. I plan in the future to build two long period > seismonitors, one that is 1Hz and other that is 0.1Hz (SG seismonitor, > if possible) to monitor teleseimic earthquakes. With my current hardware > i can detect most regonal earthquakes that are 4.5Mb or larger along > with local earthquakes that i detect alot of. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Re[2]: Long period seismonitor sensitivity ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Sun, 19 Mar 2006 23:07:35 +0000 Hi Angel I am happy to know that somebody is taking intrest in my earthquake recordings. I don't get many large earthquakes, but i get alot of smaller earthquakes. That is why i want to build teleseismic station, to monitor the large distant earthquakes that happen, also to be able to monitor regonal earthquakes better. I also plan to use the seismonitor to monitor volcano activie better, since my current geophone is limited by 2Hz cutoff. But volcano eruption tremors can go alot lower then that. I am not ready for fluid seismonitors yet, but i find the consept intresting. Since i have to learn more about normal seismonitors before i can start to understand the working of a fluid seismonitors. Everything takes time and i plan to take a good time to learn this type of science. I also have limited space for seismonitors. As can been seen on the noise of my geophone graphs. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: geophone location From: "Geoffrey" gmvoeth@........... Date: Sun, 19 Mar 2006 21:20:40 -0700 Hello; Am I the only one or do others of you out there have geophones in crowded locations like this: http://users.isp.com/gmvoethb293690/AJAZUSA.JPG Regards; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: geophone location From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 20 Mar 2006 05:14:04 +0000 Hi Geoffrey I live in a small town, with about ~680 ppl liveing in it. There isn't alot of issue that i deal with. But car and other motor driven noise is modrate and not exessive. I have my geophone inside to shield it from weather noise. You can see the town where i live here http://www.ismennt.is/not/jonasg/0landid/jg02/hvammstangi/hvammstangi-93-18507.jpg The block where i live is North of the picture (left part of the picture). It is the block north (with a white walls and a brown type of roof) of the house with the two red roofs. This picture is a bit old, few buildings are missing from it. I hope that you can find it, but this is the town where i live. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: geophone location From: ian ian@........... Date: Mon, 20 Mar 2006 09:14:50 +0000 not to be out done(!), here's my location: http://www.gohawaiian.net/northrigSatPic.jpg The pin points to my house. Despite it all, I still get loads of noise from my 3 neighbours, wind and the oceans. The gash behind my house is a pleasant narrow valley, with a 6ft wide river (burn). One day I'll dig a deep hole and build a proper vault. Ian J�n Fr�mann wrote: >Hi Geoffrey > >I live in a small town, with about ~680 ppl liveing in it. There isn't >alot of issue that i deal with. But car and other motor driven noise is >modrate and not exessive. I have my geophone inside to shield it from >weather noise. You can see the town where i live here >http://www.ismennt.is/not/jonasg/0landid/jg02/hvammstangi/hvammstangi-93-18507.jpg > >The block where i live is North of the picture (left part of the >picture). It is the block north (with a white walls and a brown type of >roof) of the house with the two red roofs. This picture is a bit old, >few buildings are missing from it. I hope that you can find it, but this >is the town where i live. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Unidentified Signal From: "Geoffrey" gmvoeth@........... Date: Mon, 20 Mar 2006 20:31:00 -0700 Hello PSN: This seems to be an EQ but I can not get any confirmation. Does anyone concurr ? http://users.isp.com/gmvoethb293690/UEQ.BMP http://users.isp.com/gmvoethb293690/UEQ.WAV http://users.isp.com/gmvoethb293690/UEQ.PSN Regards; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Unidentified Signal From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 21 Mar 2006 03:47:20 +0000 Hi Geoffrey You might have recored a 5.0Mb earthquake in Mexico, see here http://www.emsc-csem.org/index.php?page=current&sub=detail&id=HU976;2006 Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Signal To Noise Ratio of a Seismic Sensor From: "Geoffrey" gmvoeth@........... Date: Sat, 25 Mar 2006 02:25:33 -0700 Hello PSN: Can someone out there run down a list of best ways to increase the signal to noise ratio of a seismic sensor ? Things like: 1. in a mass spring system use a larger mass 2. use a phased array 3. use low resistance's in the circuitry 4. use a narrow bandwidth 5. use a high Q 6. shield everything against anything not a seismic signal. 7. a high signal to noise ratio is not possible for the average amateur due to cost it might take a bunch of amatures to pool their monies and talents to create a decent seismic sensor, possibly such a thing is only possible at a university where both money and talent exists. Does any know of a system out there with the highest signal to noise ratio...if so can we see it ? More then likely it is in military hands and is secret ? In all the discussions I have seen in this group none seem to concentrate on signal to noise ratio. Sincerely; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: ian ian@........... Date: Sat, 25 Mar 2006 10:19:32 +0000 I increased the s/n ratio by getting those small cubic super magnets, arranging them in a column and have them sit inside the core of the pickup coil. They move with the arm of the Lehman sensor (being attached to it). Ian Geoffrey wrote: > Hello PSN: > > Can someone out there run down a list of > best ways to increase the signal to noise > ratio of a seismic sensor ? > > Things like: > 1. in a mass spring system use a larger mass > 2. use a phased array > 3. use low resistance's in the circuitry > 4. use a narrow bandwidth > 5. use a high Q > 6. shield everything against anything not a seismic signal. > 7. a high signal to noise ratio is not possible for the average > amateur due to cost > it might take a bunch of amatures to pool their monies and talents to > create a decent seismic sensor, possibly such a thing is only possible > at a university where both money and talent exists. > > Does any know of a system out there with the > highest signal to noise ratio...if so can we see it ? > > More then likely it is in military hands > and is secret ? > > In all the discussions I have seen in this group > none seem to concentrate on signal to noise ratio. > > Sincerely; > gmvoeth > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: ian ian@........... Date: Sat, 25 Mar 2006 11:54:14 +0000 just to clarify what I said about magnets, I've drawn a simple sketch: http://www.iasmith.com/pickup.gif Hope that helps Ian Geoffrey wrote: > Hello PSN: > > Can someone out there run down a list of > best ways to increase the signal to noise > ratio of a seismic sensor ? > > Things like: > 1. in a mass spring system use a larger mass > 2. use a phased array > 3. use low resistance's in the circuitry > 4. use a narrow bandwidth > 5. use a high Q > 6. shield everything against anything not a seismic signal. > 7. a high signal to noise ratio is not possible for the average > amateur due to cost > it might take a bunch of amatures to pool their monies and talents to > create a decent seismic sensor, possibly such a thing is only possible > at a university where both money and talent exists. > > Does any know of a system out there with the > highest signal to noise ratio...if so can we see it ? > > More then likely it is in military hands > and is secret ? > > In all the discussions I have seen in this group > none seem to concentrate on signal to noise ratio. > > Sincerely; > gmvoeth > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: John Popelish jpopelish@........ Date: Sat, 25 Mar 2006 13:01:51 -0500 ian wrote: > just to clarify what I said about magnets, I've drawn a simple sketch: > http://www.iasmith.com/pickup.gif You might crank the signal up a bit more by splitting that stack of magnets in half, and clamping or gluing them on opposite sides of an iron slug, with the magnets repelling each other at the attachment to the slug. The slug should sit in the center of the coil. The coil generates voltage in proportion to the flux that is passing radially through the coil, and this arrangement crowds a lot more of the flux in that direction. It also makes the total magnetic field balanced, so that the Earth's magnetic field cannot push or pull on the magnets as it changes. This reduces interference from things like solar storms. Your present design wasts a lot of flux that passes out the hole in the coil and generates no signal. Making the change I am suggesting might double your signal while reducing some sources of interference and not increasing resistive noise at all. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: ChrisAtUpw@....... Date: Sat, 25 Mar 2006 17:24:28 EST In a message dated 25/03/2006, gmvoeth@........... writes: Can someone out there run down a list of best ways to increase the signal to noise ratio of a seismic sensor? Hi Geoff, Wow, a BIG subject! Difficult to cover everything. Things like: 1. in a mass spring system use a larger mass Above about 35 gm, the intrinsic kT noise of the mass is less than natural noise. For 'safety', use maybe 5x to 10x this as minimum. For a spring / mass system the ends of the spring need to be straight wires effectively clamped. The same applies to suspension systems. Good clamp design is important. The mass should preferably be non magnetic. No horse shoe or open pole magnets should be mounted on the armature. This is just asking for trouble and you will get it! Mount the sensor and damping magnets on the baseplate and put the coils and damping plates on the arm. Note that carefully designed 'potcore' magnets are used as the mass in some seismometers. These do not have a high external magnetic field. 2. use a phased array This would allow you to cancel much of the local environmental noise if it is physically large, but it is a major undertaking. 3. use low resistance's in the circuitry Choose the amplifier noise impedance to roughly match the sensor resistance. 4. use a narrow bandwidth This can be fairly critical. However it varies with the local noise and the range of the signal that you want to detect. For local and near regional signals you need maybe 10 to 20 Hz. For teleseismic quakes you may only need 2 to 3 Hz, or less. In noisy situations you need properly matched fairly sharp cut-off multipole filters. You may also wish to provide a high pass filter to reduce VLF 1/f noise. 5. use a high Q Oscillators for driving sensor systems need to have very good frequency and amplitude stability. 6. shield everything against anything not a seismic signal. Agreed, but you do need a single effective earthing point, usually linked to the input of the first opamp where you have the minimum signal. 7. a high signal to noise ratio is not possible for the average amateur due to cost it might take a bunch of amateurs to pool their moneys and talents to create a decent seismic sensor, possibly such a thing is only possible at a university where both money and talent exists. I disagree entirely. Amateurs should be able to achieve instrument noise levels below their local ambient seismic levels without great difficulty. The more likely problems are interference, RF, magnetic or static electric, poor earthing, poor shielding, utility supply signals and noise and local environmental noise commonly due to wind, lightning and static electric discharge, human activity including ordinary movement, cars, lorries and other road traffic, trains, road and building work, quarrying, power plants, heavy machinery, mining.... You need to try to identify the noise sources. It may be that you need to treat your site as though it were a heavy engineering factory and use isolating transformers and filters for supplying your system and the computer, sealed metal cases, common point earthing and braided screened connecting cables. It is no accident that most seismic sites are well away from human activity and fully encased borehole instruments are often used, buried maybe 100 m below ground level. This eliminates a great deal of the surface and weather related noise. However, the design of sensor and damping systems is very important. It is quite easy to increase the output of a system which used a coil and a horse shoe magnet, by using a NdFeB magnet array and a smaller coil. For a Lehman, I use two 1/4" thick mild steel plates, 3.5" long by 2" wide. The corners are drilled to take 1/4" mild steel set screws 2.5" long with mild steel washers and nuts. The two plates are held maybe 3/4" to 1" apart for a sensor, using three nuts on every bolt. A bolt is firmly secured to one plate using a nut. The second plate is mounted in between pairs of nuts on the free thread, to allow the separation of the plates to be adjusted. Four NdFeB magnets 1/8" thick by 1" square are mounted on the inside faces of the plates. A N+S pair on one face is opposed by a S+N pair on the other. The sensor coil is mounted in the high intensity magnetic field in the centre. This construction gives quite an effective magnetic and electrostatic screen around the coil. The external stray field is low. The sensitivity is high due to the high field and the response is reasonably linear. If you use rectangular instead of round coils, it can be made very highly linear over +/-1/2" movement. For induced current damping, I use four NdFeB bar magnets 1"x1/2"x1/4" thick in two opposing squares, with the same 1/4" steel plate mounting. I use a copper damping plate, 1/16" to 1/8" thick as appropriate, a bit over 2" wide and 2.5" free length. This allows the arm to swing +/-1/2" without the edge of the copper plate overlapping the edge of the 1" magnet square. The N+S join of the magnet pairs is set perpendicular to the direction of motion. The damping is adjusted by varying by the length of copper tongue overlapping the magnet square and also by varying the separation of the 1/4" mild steel plates and hence the magnet separations. Does any know of a system out there with the highest signal to noise ratio...if so can we see it ? More then likely it is in military hands and is secret ? More likely to be a commercial secret of the various seismometer manufacturers! It takes quite a bit of effort to get the instrument noise below the minimum earth noise levels. However, unless you are very fortunate with your site, you are very unlikely to see seismic noise levels even approaching that low. Try either wedging your sensor in a fixed position or substituting a resistor for it and running the whole system for 24 hrs on a weekday. This should demonstrate the amplitude and timing of many interfering signals. But it won't pick up sensor movement due to drafts, local magnetic field changes (including the earth, your refrigerators, car, bicycle or mowing machine), ground movement or tilt, insects or animals. Then you have the interesting task of identifying these sources and eliminating the effects. Compare the signals and timing with an active trace taken a seismically quiet day. Get onto the www and see how ham radio operators deal with earthing in your area, also the utility company. There are large areas of the US where the rocks and soils are dry and have very poor electrical conductivity. Your house or mobile home wiring may be sticking way up above the effective local 'earth' plane. For noise coming in through the utility wiring, you can provide a filter, but check that this has a good rejection from a few hundred Hz up and is not simply an RF filter. The next stage is to use a 1:1 isolating transformer with a metal case and an electrostatic screen in between the windings. Consider providing a separate Earth for the screen, the case and the electronics. The more extreme alternative is to use two batteries, one to drive the equipment and a laptop computer while the other is charged on a separate power circuit. An alternative is to use a large ferrite core transformer, similar to that in a TV set, to provide a 15 kHz isolated charging circuit. You can also use optical or radio links to transfer data to and from the phone system. Hope that these comments / suggestions are of some help. Regards, Chris Chapman

In a message dated 25/03/2006, gmvoeth@........... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Can=20 someone out there run down a list of best ways to increase the signal to=20 noise
ratio of a seismic sensor?

Hi Geoff,

Wow, a BIG subject! Difficult to cover=20 everything.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Things=20 like:
1. in a mass spring system use a larger mass

Above about 35 gm, the intrinsic kT noise of th= e=20 mass is less than natural noise. For 'safety', use maybe 5x to 10x this as=20 minimum.

For a spring / mass system the ends of the spri= ng=20 need to be straight wires effectively clamped. The same applies to suspensio= n=20 systems. Good clamp design is important.

The mass should preferably be non magnetic.

No horse shoe or open pole magnets should be=20 mounted on the armature. This is just asking for trouble and you= =20 will get it! Mount the sensor and damping magnets on the basep= late=20 and put the coils and damping plates on the arm. Note that carefully=20 designed 'potcore' magnets are used as the mass in some seismometers. T= hese=20 do not have a high external magnetic field.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>2. use a=20 phased array

This would allow you to cancel much of the=20 local environmental noise if it is physically large, but it is a m= ajor=20 undertaking.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>3. use=20 low resistance's in the circuitry

Choose the amplifier noise impedance to=20 roughly match the sensor resistance.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>4. use a=20 narrow bandwidth

This can be fairly critical. However it varies=20= with=20 the local noise and the range of the signal that you want to detect. For loc= al=20 and near regional signals you need maybe 10 to 20 Hz. For teleseismic quakes= you=20 may only need 2 to 3 Hz, or less.

In noisy situations you need properly matched=20 fairly sharp cut-off multipole filters.

You may also wish to provide a high pass filter= to=20 reduce VLF 1/f noise.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>5. use a=20 high Q

Oscillators for driving sensor systems need to=20= have=20 very good frequency and amplitude stability.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>6.=20 shield everything against anything not a seismic signal.

Agreed, but you do need a single effective eart= hing=20 point, usually linked to the input of the first opamp where you have the min= imum=20 signal.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>7. a=20 high signal to noise ratio is not possible for the average amateur due to=20 cost
   it might take a bunch of amateurs to pool their money= s=20 and talents to
   create a decent seismic sensor, possibly su= ch a=20 thing is only possible
   at a university where both money an= d=20 talent exists.

I disagree entirely.

Amateurs should be able to achieve instrument n= oise=20 levels below their local ambient seismic levels without great=20 difficulty.

The more likely problems are interference,= RF,=20 magnetic or static electric, poor earthing, poor shielding, utility=20 supply signals and noise and local environmental noise commonly du= e to=20 wind, lightning and static electric discharge, human activity including ordi= nary=20 movement, cars, lorries and other road traffic, trains, road and building wo= rk,=20 quarrying, power plants, heavy machinery, mining.... You need to try to iden= tify=20 the noise sources.

It may be that you need to treat your site as=20 though it were a heavy engineering factory and use isolating transformers an= d=20 filters for supplying your system and the computer, sealed metal cases, comm= on=20 point earthing and braided screened connecting cables.

It is no accident that most seismic sites=20 are well away from human activity and fully encased borehole instrument= s=20 are often used, buried maybe 100 m below ground level. This eliminates a gre= at=20 deal of the surface and weather related noise.

However, the design of sensor and damping syste= ms=20 is very important. It is quite easy to increase the output of a system which= =20 used a coil and a horse shoe magnet, by using a NdFeB magnet array and a sma= ller=20 coil.

For a Lehman, I use two 1/4" thick mild steel=20 plates, 3.5" long by 2" wide. The corners are drilled to take 1/4" mild stee= l=20 set screws 2.5" long with mild steel washers and nuts. The two plates a= re=20 held maybe 3/4" to 1" apart for a sensor, using three nuts on every bolt.=20 A bolt is firmly secured to one plate using a nut. The second plate is=20 mounted in between pairs of nuts on the free thread, to allow the separation= of=20 the plates to be adjusted. Four NdFeB magnets 1/8" thick by 1" square are=20 mounted on the inside faces of the plates. A N+S pair on one face is=20 opposed by a S+N pair on the other. The sensor coil is mounted in the high=20 intensity magnetic field in the centre.

This construction gives quite an effective magn= etic=20 and electrostatic screen around the coil. The external stray field is low. T= he=20 sensitivity is high due to the high field and the response is reasonably lin= ear.=20 If you use rectangular instead of round coils, it can be made very highly li= near=20 over +/-1/2" movement.

For induced current damping, I=20 use four NdFeB bar magnets 1"x1/2"x1/4" thick in two opposing squa= res,=20 with the same 1/4" steel plate mounting. I use a copper damping plate,=20 1/16" to 1/8" thick as appropriate, a bit over 2" wide and 2.= 5"=20 free length. This allows the arm to swing +/-1/2" without the edge of the co= pper=20 plate overlapping the edge of the 1" magnet square. The N+S join of the magn= et=20 pairs is set perpendicular to the direction of motion. The damping is adjust= ed=20 by varying by the length of copper tongue overlapping the magnet square and=20= also=20 by varying the separation of the 1/4" mild steel plates and hence the magnet= =20 separations.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Does any=20 know of a system out there with the
highest signal to noise ratio...if=20= so=20 can we see it ?

More then likely it is in military hands and is sec= ret=20 ?

More likely to be a commercial secret of t= he=20 various seismometer manufacturers! It takes quite a bit of effort to get the= =20 instrument noise below the minimum earth noise levels. However, unless=20= you=20 are very fortunate with your site, you are very unlikely to see seismic nois= e=20 levels even approaching that low.

Try either wedging your sensor in a fixed posit= ion=20 or substituting a resistor for it and running the whole system for 24 hrs on= a=20 weekday. This should demonstrate the amplitude and timing of many interferin= g=20 signals. But it won't pick up sensor movement due to drafts, local magnetic=20 field changes (including the earth, your refrigerators, car, bicycle or mowi= ng=20 machine), ground movement or tilt, insects or animals. Then you have the=20 interesting task of identifying these sources and eliminating the effects.=20 Compare the signals and timing with an active trace taken a seismically quie= t=20 day.

Get onto the www and see how ham radio operator= s=20 deal with earthing in your area, also the utility company. There are large a= reas=20 of the US where the rocks and soils are dry and have very poor electrical=20 conductivity. Your house or mobile home wiring may be sticking way up above=20= the=20 effective local 'earth' plane.

For noise coming in through the utility wiring,= you=20 can provide a filter, but check that this has a good rejection from a few=20 hundred Hz up and is not simply an RF filter. The next stage is to use a 1:1= =20 isolating transformer with a metal case and an electrostatic sc= reen=20 in between the windings. Consider providing a separate Earth f= or=20 the screen, the case and the electronics. The more extreme alterna= tive=20 is to use two batteries, one to drive the equipment and a laptop computer wh= ile=20 the other is charged on a separate power circuit. An alternative is to=20= use=20 a large ferrite core transformer, similar to that in a TV set, to provide a=20= 15=20 kHz isolated charging circuit. You can also use optical or radio links=20= to=20 transfer data to and from the phone system.

Hope that these comments / suggestions are of s= ome=20 help.

Regards,

Chris Chapman

Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: Dave Nelson davenn@............... Date: Sun, 26 Mar 2006 08:34:01 +1000 Agree with you John, Ian, as shown in your drawing 1/2 of your magnets are outside the coil area and only one side of the supporting bar. This severely reduces the amount of voltage generated in the coils. As to Geoffery's questions, another good rule is ALWAYS use love noise components.... Bi-FET Op-Amps .... eg the OPA 027 and similar series, rather 741 etc type Metal Film resistors ... particularly are much lower noise producing than standard carbon resistors I have also always used coaxial cable for feedline between the sensor and the preamp board. and for the short period geophones ... Bury them ! even 6 inches below ground level cuts out a lot of stray RF field pickup and other electrical noise. cheers Dave At 01:01 PM 25/03/2006 -0500, you wrote: >ian wrote: >>just to clarify what I said about magnets, I've drawn a simple sketch: >>http://www.iasmith.com/pickup.gif > >You might crank the signal up a bit more by splitting that stack of >magnets in half, and clamping or gluing them on opposite sides of an iron >slug, with the magnets repelling each other at the attachment to the >slug. The slug should sit in the center of the coil. > >The coil generates voltage in proportion to the flux that is passing >radially through the coil, and this arrangement crowds a lot more of the >flux in that direction. It also makes the total magnetic field balanced, >so that the Earth's magnetic field cannot push or pull on the magnets as >it changes. This reduces interference from things like solar storms. > >Your present design wasts a lot of flux that passes out the hole in the >coil and generates no signal. Making the change I am suggesting might >double your signal while reducing some sources of interference and not >increasing resistive noise at all. -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 24/03/2006 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: Dave Nelson davenn@............... Date: Sun, 26 Mar 2006 08:44:02 +1000 dont ya just love typo's As to Geoffery's questions, another good rule is ALWAYS use love noise components.... should read .. ALWAYS use low noise components.... snip Dave N -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 24/03/2006 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: ChrisAtUpw@....... Date: Sat, 25 Mar 2006 18:45:16 EST In a message dated 25/03/2006, davenn@............... writes: Bi-FET Op-Amps .... eg the OPA 027 and similar series, rather 741 etc type Hi Dave, Google can't find an OPA027 ! and neither can I !! OPA27 are very low noise, but they are not Bi-FET The later types are OPA227 LT1007 etc In general, FET opamps have a much higher voltage noise than ordinary transistor types. I would not use one by choice in a geophone or a coil sensor circuit. Some of the less expensive / older types suffer from step noise - transient level or pulsed shifts. When you connect up a geophone, you need to wire the metal case to the earth / shield line. Regards, Chris Chapman

In a message dated 25/03/2006, davenn@............... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2> =20 Bi-FET Op-Amps .... eg the OPA 027&nb= sp;=20 and similar
series, rather 741 etc=20 type

Hi Dave,

Google can't find an OPA027 ! and neither can I= =20 !!

OPA27 are very low noise, but they are not Bi-F= ET=20 The later types are OPA227 LT1007 etc

In general, FET opamps have a much higher volta= ge=20 noise than ordinary transistor types. I would not use one by choice in=20= a=20 geophone or a coil sensor circuit. Some of the less expensive / older types=20 suffer from step noise - transient level or pulsed shifts.

When you connect up a geophone, you need t= o=20 wire the metal case to the earth / shield line.

Regards,

Chris Chapman

Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: Dave Nelson davenn@............... Date: Sun, 26 Mar 2006 15:03:46 +1000 yup Chris jst some more typo's :) cheers Dave At 06:45 PM 25/03/2006 -0500, you wrote: >In a message dated 25/03/2006, davenn@............... writes: > Bi-FET Op-Amps .... eg the OPA 027 and similar >series, rather 741 etc type >Hi Dave, > Google can't find an OPA027 ! and neither can I !! > OPA27 are very low noise, but they are not Bi-FET The later types are > OPA227 LT1007 etc > In general, FET opamps have a much higher voltage noise than ordinary > transistor types. I would not use one by choice in a geophone or a coil > sensor circuit. Some of the less expensive / older types suffer from step > noise - transient level or pulsed shifts. > > When you connect up a geophone, you need to wire the metal case to > the earth / shield line. > > Regards, > > Chris Chapman > > >No virus found in this incoming message. >Checked by AVG Anti-Virus. >Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 24/03/2006 yup Chris

jst some more typo's :)

cheers
Dave

At 06:45 PM 25/03/2006 -0500, you wrote:

In a message dated 25/03/2006, davenn@............... writes:

Bi-FET Op-Amps     .... eg the OPA 027 and similar
series, rather 741   etc type
Hi Dave,
    Google can't find an OPA027 ! and neither can I !!
    OPA27 are very low noise, but they are not Bi-FET The later types are OPA227 LT1007 etc
    In general, FET opamps have a much higher voltage noise than ordinary transistor types. I would not use one by choice in a geophone or a coil sensor circuit. Some of the less expensive / older types suffer from step noise - transient level or pulsed shifts.

    When you connect up a geophone, you need to wire the metal case to the earth / shield line.

    Regards,

    Chris Chapman

No virus found in this incoming message.
Checked by AVG Anti-Virus.
Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 24/03/2006

No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 24/03/2006 Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: ian ian@........... Date: Sun, 26 Mar 2006 07:56:02 +0100 sketches or pictures would be very useful for the suggested magnet arrangements... TIA Ian ChrisAtUpw@....... wrote: > In a message dated 25/03/2006, gmvoeth@........... writes: > > Can someone out there run down a list of best ways to increase the > signal to noise > ratio of a seismic sensor? > > Hi Geoff, > > Wow, a BIG subject! Difficult to cover everything. > > Things like: > 1. in a mass spring system use a larger mass > > Above about 35 gm, the intrinsic kT noise of the mass is less than > natural noise. For 'safety', use maybe 5x to 10x this as minimum. > For a spring / mass system the ends of the spring need to be > straight wires effectively clamped. The same applies to suspension > systems. Good clamp design is important. > The mass should preferably be non magnetic. > No horse shoe or open pole magnets should be mounted on the > armature. This is just asking for trouble and you will get it! Mount > the sensor and damping magnets on the baseplate and put the coils and > damping plates on the arm. Note that carefully designed 'potcore' > magnets are used as the mass in some seismometers. These do not have a > high external magnetic field. > > 2. use a phased array > > This would allow you to cancel much of the local environmental > noise if it is physically large, but it is a major undertaking. > > 3. use low resistance's in the circuitry > > Choose the amplifier noise impedance to roughly match the sensor > resistance. > > 4. use a narrow bandwidth > > This can be fairly critical. However it varies with the local > noise and the range of the signal that you want to detect. For local > and near regional signals you need maybe 10 to 20 Hz. For teleseismic > quakes you may only need 2 to 3 Hz, or less. > In noisy situations you need properly matched fairly sharp cut-off > multipole filters. > You may also wish to provide a high pass filter to reduce VLF 1/f > noise. > > 5. use a high Q > > Oscillators for driving sensor systems need to have very good > frequency and amplitude stability. > > 6. shield everything against anything not a seismic signal. > > Agreed, but you do need a single effective earthing point, usually > linked to the input of the first opamp where you have the minimum signal. > > 7. a high signal to noise ratio is not possible for the average > amateur due to cost > it might take a bunch of amateurs to pool their moneys and > talents to > create a decent seismic sensor, possibly such a thing is only > possible > at a university where both money and talent exists. > > I disagree entirely. > Amateurs should be able to achieve instrument noise levels below > their local ambient seismic levels without great difficulty. > The more likely problems are interference, RF, magnetic or static > electric, poor earthing, poor shielding, utility supply signals and > noise and local environmental noise commonly due to wind, lightning > and static electric discharge, human activity including ordinary > movement, cars, lorries and other road traffic, trains, road and > building work, quarrying, power plants, heavy machinery, mining.... > You need to try to identify the noise sources. > It may be that you need to treat your site as though it were a > heavy engineering factory and use isolating transformers and filters > for supplying your system and the computer, sealed metal cases, common > point earthing and braided screened connecting cables. > It is no accident that most seismic sites are well away from human > activity and fully encased borehole instruments are often used, buried > maybe 100 m below ground level. This eliminates a great deal of the > surface and weather related noise. > > However, the design of sensor and damping systems is very > important. It is quite easy to increase the output of a system which > used a coil and a horse shoe magnet, by using a NdFeB magnet array and > a smaller coil. > > For a Lehman, I use two 1/4" thick mild steel plates, 3.5" long by > 2" wide. The corners are drilled to take 1/4" mild steel set screws > 2.5" long with mild steel washers and nuts. The two plates are held > maybe 3/4" to 1" apart for a sensor, using three nuts on every bolt. > A bolt is firmly secured to one plate using a nut. The second plate is > mounted in between pairs of nuts on the free thread, to allow the > separation of the plates to be adjusted. Four NdFeB magnets 1/8" thick > by 1" square are mounted on the inside faces of the plates. A N+S > pair on one face is opposed by a S+N pair on the other. The sensor > coil is mounted in the high intensity magnetic field in the centre. > This construction gives quite an effective magnetic and > electrostatic screen around the coil. The external stray field is low. > The sensitivity is high due to the high field and the response is > reasonably linear. If you use rectangular instead of round coils, it > can be made very highly linear over +/-1/2" movement. > For induced current damping, I use four NdFeB bar magnets > 1"x1/2"x1/4" thick in two opposing squares, with the same 1/4" steel > plate mounting. I use a copper damping plate, 1/16" to 1/8" thick as > appropriate, a bit over 2" wide and 2.5" free length. This allows the > arm to swing +/-1/2" without the edge of the copper plate overlapping > the edge of the 1" magnet square. The N+S join of the magnet pairs is > set perpendicular to the direction of motion. The damping is adjusted > by varying by the length of copper tongue overlapping the magnet > square and also by varying the separation of the 1/4" mild steel > plates and hence the magnet separations. > > Does any know of a system out there with the > highest signal to noise ratio...if so can we see it ? > > More then likely it is in military hands and is secret ? > > More likely to be a commercial secret of the various seismometer > manufacturers! It takes quite a bit of effort to get the instrument > noise below the minimum earth noise levels. However, unless you are > very fortunate with your site, you are very unlikely to see seismic > noise levels even approaching that low. > > Try either wedging your sensor in a fixed position or substituting > a resistor for it and running the whole system for 24 hrs on a > weekday. This should demonstrate the amplitude and timing of many > interfering signals. But it won't pick up sensor movement due to > drafts, local magnetic field changes (including the earth, your > refrigerators, car, bicycle or mowing machine), ground movement or > tilt, insects or animals. Then you have the interesting task of > identifying these sources and eliminating the effects. Compare the > signals and timing with an active trace taken a seismically quiet day. > > Get onto the www and see how ham radio operators deal with > earthing in your area, also the utility company. There are large areas > of the US where the rocks and soils are dry and have very poor > electrical conductivity. Your house or mobile home wiring may be > sticking way up above the effective local 'earth' plane. > > For noise coming in through the utility wiring, you can provide a > filter, but check that this has a good rejection from a few hundred Hz > up and is not simply an RF filter. The next stage is to use a 1:1 > isolating transformer with a metal case and an electrostatic screen in > between the windings. Consider providing a separate Earth for > the screen, the case and the electronics. The more extreme alternative > is to use two batteries, one to drive the equipment and a laptop > computer while the other is charged on a separate power circuit. An > alternative is to use a large ferrite core transformer, similar to > that in a TV set, to provide a 15 kHz isolated charging circuit. You > can also use optical or radio links to transfer data to and from the > phone system. > > Hope that these comments / suggestions are of some help. > > Regards, > > Chris Chapman sketches or pictures would be very useful for the suggested magnet arrangements...

TIA

Ian

ChrisAtUpw@....... wrote:

In a message dated 25/03/2006, gmvoeth@........... writes:

Can someone out there run down a list of best ways to increase the signal to noise
ratio of a seismic sensor?

Hi Geoff,

    Wow, a BIG subject! Difficult to cover everything.

Things like:
1. in a mass spring system use a larger mass

    Above about 35 gm, the intrinsic kT noise of the mass is less than natural noise. For 'safety', use maybe 5x to 10x this as minimum.

    For a spring / mass system the ends of the spring need to be straight wires effectively clamped. The same applies to suspension systems. Good clamp design is important.

    The mass should preferably be non magnetic.

    No horse shoe or open pole magnets should be mounted on the armature. This is just asking for trouble and you will get it! Mount the sensor and damping magnets on the baseplate and put the coils and damping plates on the arm. Note that carefully designed 'potcore' magnets are used as the mass in some seismometers. These do not have a high external magnetic field.

2. use a phased array

    This would allow you to cancel much of the local environmental noise if it is physically large, but it is a major undertaking.

3. use low resistance's in the circuitry

    Choose the amplifier noise impedance to roughly match the sensor resistance.

4. use a narrow bandwidth

    This can be fairly critical. However it varies with the local noise and the range of the signal that you want to detect. For local and near regional signals you need maybe 10 to 20 Hz. For teleseismic quakes you may only need 2 to 3 Hz, or less.

    In noisy situations you need properly matched fairly sharp cut-off multipole filters.

    You may also wish to provide a high pass filter to reduce VLF 1/f noise.

5. use a high Q

    Oscillators for driving sensor systems need to have very good frequency and amplitude stability.

6. shield everything against anything not a seismic signal.

    Agreed, but you do need a single effective earthing point, usually linked to the input of the first opamp where you have the minimum signal.

7. a high signal to noise ratio is not possible for the average amateur due to cost
   it might take a bunch of amateurs to pool their moneys and talents to
   create a decent seismic sensor, possibly such a thing is only possible
   at a university where both money and talent exists.

    I disagree entirely.

    Amateurs should be able to achieve instrument noise levels below their local ambient seismic levels without great difficulty.

    The more likely problems are interference, RF, magnetic or static electric, poor earthing, poor shielding, utility supply signals and noise and local environmental noise commonly due to wind, lightning and static electric discharge, human activity including ordinary movement, cars, lorries and other road traffic, trains, road and building work, quarrying, power plants, heavy machinery, mining.... You need to try to identify the noise sources.

    It may be that you need to treat your site as though it were a heavy engineering factory and use isolating transformers and filters for supplying your system and the computer, sealed metal cases, common point earthing and braided screened connecting cables.

    It is no accident that most seismic sites are well away from human activity and fully encased borehole instruments are often used, buried maybe 100 m below ground level. This eliminates a great deal of the surface and weather related noise.

    However, the design of sensor and damping systems is very important. It is quite easy to increase the output of a system which used a coil and a horse shoe magnet, by using a NdFeB magnet array and a smaller coil.



    For a Lehman, I use two 1/4" thick mild steel plates, 3.5" long by 2" wide. The corners are drilled to take 1/4" mild steel set screws 2.5" long with mild steel washers and nuts. The two plates are held maybe 3/4" to 1" apart for a sensor, using three nuts on every bolt. A bolt is firmly secured to one plate using a nut. The second plate is mounted in between pairs of nuts on the free thread, to allow the separation of the plates to be adjusted. Four NdFeB magnets 1/8" thick by 1" square are mounted on the inside faces of the plates. A N+S pair on one face is opposed by a S+N pair on the other. The sensor coil is mounted in the high intensity magnetic field in the centre.

    This construction gives quite an effective magnetic and electrostatic screen around the coil. The external stray field is low. The sensitivity is high due to the high field and the response is reasonably linear. If you use rectangular instead of round coils, it can be made very highly linear over +/-1/2" movement.

    For induced current damping, I use four NdFeB bar magnets 1"x1/2"x1/4" thick in two opposing squares, with the same 1/4" steel plate mounting. I use a copper damping plate, 1/16" to 1/8" thick as appropriate, a bit over 2" wide and 2.5" free length. This allows the arm to swing +/-1/2" without the edge of the copper plate overlapping the edge of the 1" magnet square. The N+S join of the magnet pairs is set perpendicular to the direction of motion. The damping is adjusted by varying by the length of copper tongue overlapping the magnet square and also by varying the separation of the 1/4" mild steel plates and hence the magnet separations.

Does any know of a system out there with the
highest signal to noise ratio...if so can we see it ?

More then likely it is in military hands and is secret ?

    More likely to be a commercial secret of the various seismometer manufacturers! It takes quite a bit of effort to get the instrument noise below the minimum earth noise levels. However, unless you are very fortunate with your site, you are very unlikely to see seismic noise levels even approaching that low.

    Try either wedging your sensor in a fixed position or substituting a resistor for it and running the whole system for 24 hrs on a weekday. This should demonstrate the amplitude and timing of many interfering signals. But it won't pick up sensor movement due to drafts, local magnetic field changes (including the earth, your refrigerators, car, bicycle or mowing machine), ground movement or tilt, insects or animals. Then you have the interesting task of identifying these sources and eliminating the effects. Compare the signals and timing with an active trace taken a seismically quiet day.

    Get onto the www and see how ham radio operators deal with earthing in your area, also the utility company. There are large areas of the US where the rocks and soils are dry and have very poor electrical conductivity. Your house or mobile home wiring may be sticking way up above the effective local 'earth' plane.

    For noise coming in through the utility wiring, you can provide a filter, but check that this has a good rejection from a few hundred Hz up and is not simply an RF filter. The next stage is to use a 1:1 isolating transformer with a metal case and an electrostatic screen in between the windings. Consider providing a separate Earth for the screen, the case and the electronics. The more extreme alternative is to use two batteries, one to drive the equipment and a laptop computer while the other is charged on a separate power circuit. An alternative is to use a large ferrite core transformer, similar to that in a TV set, to provide a 15 kHz isolated charging circuit. You can also use optical or radio links to transfer data to and from the phone system.

    Hope that these comments / suggestions are of some help.

    Regards,

    Chris Chapman

Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: ian ian@........... Date: Sun, 26 Mar 2006 07:59:20 +0100 the magnets outside the coil are just acting as a convenient support column for the ones that are inside. I'll start thinking about how to get some into the other side of the coil... Ian Dave Nelson wrote: > > Agree with you John, > Ian, as shown in your drawing 1/2 of your magnets are outside > the coil area and only one side of the supporting bar. This severely > reduces the amount of voltage generated in the coils. > > As to Geoffery's questions, > another good rule is ALWAYS use love noise components.... > > Bi-FET Op-Amps .... eg the OPA 027 and similar series, > rather 741 etc type > > Metal Film resistors ... particularly are much lower noise > producing than > standard carbon resistors > > I have also always used coaxial cable for feedline between the > sensor and the > preamp board. and for the short period geophones ... Bury them ! > even 6 inches below ground level cuts out a lot of stray RF field > pickup and other electrical noise. > > cheers > Dave > > > > At 01:01 PM 25/03/2006 -0500, you wrote: > >> ian wrote: >> >>> just to clarify what I said about magnets, I've drawn a simple sketch: >>> http://www.iasmith.com/pickup.gif >> >> >> You might crank the signal up a bit more by splitting that stack of >> magnets in half, and clamping or gluing them on opposite sides of an >> iron slug, with the magnets repelling each other at the attachment to >> the slug. The slug should sit in the center of the coil. >> >> The coil generates voltage in proportion to the flux that is passing >> radially through the coil, and this arrangement crowds a lot more of >> the flux in that direction. It also makes the total magnetic field >> balanced, so that the Earth's magnetic field cannot push or pull on >> the magnets as it changes. This reduces interference from things >> like solar storms. >> >> Your present design wasts a lot of flux that passes out the hole in >> the coil and generates no signal. Making the change I am suggesting >> might double your signal while reducing some sources of interference >> and not increasing resistive noise at all. > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Signal To Noise Ratio of a Seismic Sensor From: "Geoffrey" gmvoeth@........... Date: Sun, 26 Mar 2006 00:49:17 -0700 I am no expert at anything but it is my understanding you want the highest uniform magnetic field possible and you want the wires to move within that field perpendicular. So to compliment the field you will put two horseshoe type magnets in opposition with a gap then have the coil in the middle with one half cutting the N/S poles and the other half cutting the S/N poles. It seems best if the coil is smaller then the magnet faces and is rectangular rather than circular. If you could get several of those old military magnetron magnets like they use in the old days of electronics that are used for Physics demonstrations today at the universities you most probably would have the best magnet you can get. But they look like they weigh 100 lbs each. I cant imagine how you could safely create a one inch gap with those monstrous magnets. They would take off a finger or two if you were not careful in keeping them apart. No one talks about safety when playing with springs and stuff so I guess no amateurs have had any serious accidents trying to build these seismometers. sincerely; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re:Signal To Noise Ratio of a Seismic Sensor From: Roger Sparks rsparks@.......... Date: Sun, 26 Mar 2006 09:27:47 -0800 Hello All, For a good discussion of signal to noise ratio, we can begin by separating seismic noise and instrument noise. Seismic noise--Any motion of the ground or environment that generates a signal on the motion detector that is not the desired quake: 1. Local movement causing ground vibrations 2. Wind or air density change, causing a change in the "float" depth of a vertical sensing seismometer 3. Air movement around the seismometer Instrument noise--Any condition of the sensor or electronics that registers as data in the visual display: 1. Seismometer hinge--non-linearity or friction causes vibration 2. Electronic noise-- visible even when the seismometer is locked 3. Damper characteristics--Oil dampers will have internal fluid waves 4. Temperature changes Some conditions affect the amount of signal captured but do not affect the seismic signal or ground motion: 1. The size of the seismometer rest mass. 2. The period of the seismometer. Longer periods allow increased ground motion before the seismic mass will move. 3. The damper. The damper absorbs seismic energy, and can also be frequency sensitive or non-linear in response After the signal is captured, the electronics can reduce or absorb the signal: 1. Improperly set filters 2. Resistance Each of these generally named sources of noise or signal loss can be discussed in much greater detail. The effects of the signal to noise ratio can be seen by looking at the postings on the PSN website. The omnipresent microseims caused by ocean wave action are detected by many instruments and create a waveform which precludes recording a straight line trace. Small seismic signals, whether generated locally or distant, should appear as higher frequency deviations "riding" on the microseim trace. Only rarely will the seismic signal frequency exactly match the microseim frequency and therefore be masked as being a "greater microseism". BW, Roger psn-l-digest-request@.............. wrote: > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 1 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Signal To Noise Ratio of a Seismic Sensor > From: "Geoffrey" > Date: Sat, 25 Mar 2006 02:25:33 -0700 > > Hello PSN: > > Can someone out there run down a list of > best ways to increase the signal to noise > ratio of a seismic sensor ? > > Things like: > 1. in a mass spring system use a larger mass > 2. use a phased array > 3. use low resistance's in the circuitry > 4. use a narrow bandwidth > 5. use a high Q > 6. shield everything against anything not a seismic signal. > 7. a high signal to noise ratio is not possible for the average amateur due to cost > it might take a bunch of amatures to pool their monies and talents to > create a decent seismic sensor, possibly such a thing is only possible > at a university where both money and talent exists. > > Does any know of a system out there with the > highest signal to noise ratio...if so can we see it ? > > More then likely it is in military hands > and is secret ? > > In all the discussions I have seen in this group > none seem to concentrate on signal to noise ratio. > > Sincerely; > gmvoeth > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Sensor and Damping magnets From: ChrisAtUpw@....... Date: Sun, 26 Mar 2006 21:52:22 EST In a message dated 26/03/2006, gmvoeth@........... writes: it is my understanding you want the highest uniform magnetic field possible and you want the wires to move within that field perpendicular. So to compliment the field you will put two horseshoe type magnets in opposition with a gap then have the coil in the middle with one half cutting the N/S poles and the other half cutting the S/N poles. It seems best if the coil is smaller then the magnet faces and is rectangular rather than circular. Hi Geoff, Ian, If you could get several of those old military magnetron magnets like they use in the old days of electronics that are used for Physics demonstrations today at the universities you most probably would have the best magnet you can get. But they look like they weigh 100 lbs each. They can be used but they are very bulky and don't usually have the pole shape that you want. You are much better off with rectangular coils and rectangular magnets. You need two adjacent areas of opposing high intensity field. NdFeB bar magnets are not very expensive, but they are very powerful. The 'I' is soft iron plate. The 'B' are the support bolts with 3 off nuts locking the plates in place. The 'N' and 'S' are 1" square x 1/8" Neo magnets with poles on the square face. The 'CC-------CC' is a rectangular frame coil with an open centre and maybe 3,000 to 5,000 turns, about 1" wide by 1,1/4" long. The coil overlaps the ends of the magnets coming out of the paper. I used 4 paxolin rods and thin sheet held together with epoxy glue to make the coil frame. Make a reinforced hole in the centre so that you can mount the frame on a bolt in a hand drill to wind on the wire. Sensor. I have exaggerated the coil to magnet separation. Magnets 1"squarex1/8" thick with poles on the square face B B IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII B NNNNNNNNNNSSSSSSSSSS B B B B <- CC------------------CC -> B B CC------------------CC B B B B SSSSSSSSSSNNNNNNNNNN B IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII B B Damper. Cu is the wide copper damping plate, 1/16" to 1/8" thick Magnets 1"x1/2"widex1/4" thick with poles on the 1"x1/2" face View shows the 1/2"x1/4" magnet ends B 3.5" long B Mild Steel Plate IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII 1/4" thick x 2" wide B NNNNNSSSSS B B <- CuCuCuCuCuCuCuCuCuCuCuCu -> B 1/4" mild steel bolts B SSSSSNNNNN B full thread + 3 nuts IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII B B For a Lehman, I use two 1/4" thick bright mild steel plates, 3.5" long by 2" wide. The corners are drilled to take 1/4" mild steel set screws 2.5" long with mild steel washers and nuts. The two plates are held maybe 3/4" to 1" apart for a sensor, using three nuts on every bolt. A bolt is firmly secured to one plate using a nut. The second plate is mounted in between pairs of nuts on the free thread, to allow the separation of the plates to be adjusted and locked. Four NdFeB magnets 1/8" thick by 1" square are mounted on the inside faces of the plates. A N+S pair on one face is opposed by a S+N pair on the other. The sensor coil is mounted at the centre of the high intensity magnetic field. This construction gives quite an effective magnetic and electrostatic screen around the coil. The external stray field is low. The sensitivity is high due to the high field and the response is reasonably linear. If you use rectangular instead of round coils, it can be made very highly linear over +/-1/2" movement. For induced current damping, I use four NdFeB bar magnets 1"x1/2"x1/4" thick in two opposing squares, with the same 1/4" steel plate mounting, but with a much smaller magnet separation. I use a copper damping plate, 1/16" to 1/8" thick as appropriate, a bit over 2" wide and 2.5" free length. This allows the arm to swing +/-1/2" without the edge of the copper plate overlapping the edge of the 1" magnet square. The N+S join of the magnet pairs is set perpendicular to the direction of motion. The damping is adjusted by varying by the length of copper tongue overlapping the magnet square and also by varying the separation of the 1/4" mild steel plates and hence the magnet separations. Most of the damping occurs close to the central N/S magnet join. This is a very effective and easily adjusted design of damper. I have also used soft Al damping plates, but Al is usually more strongly paramagnetic than the copper is diamagnetic and it has a higher resistivity. I use the damping plate to physically limit the sideways travel of the seismometer arm. If the plate is made narrower and the arm drifts, you may get 'odd' force effects as the edge of the plate gets close to the outside edge of the magnets. Al is usually mildly paramagnetic, but copper is usually diamagnetic. I can't imagine how you could safely create a one inch gap with those monstrous magnets. They would take off a finger or two if you were not careful in keeping them apart. With some difficulty and great care! Neo magnets start to get dangerous above about 1/4" thick, 1/2" square. I have a pair 2" square by 1/2" thick. I can't put enough finger force on them to even slide them apart. I use wood blocks and an A frame work bench. Two of these magnets will 'jump together' if less than about a foot apart. Only ever handle ONE free magnet at a time! No one talks about safety when playing with springs and stuff so I guess no amateurs have had any serious accidents trying to build these seismometers. Oh yes they do! Sean's EMails carried several warnings about dry wall scraper spring systems. Construction. Cut and file the 2"x1/4" bright mild steel to length. Mark out the 3 or 4 bolt holes to choice on one plate, then clamp the two plates together and drill all the clearance holes through both plates at the same time. Mark the plate orientation with a centre punch. This ensures perfect bolt alignment. Degrease, then coat the steel with acid anti rust liquid / paste, leave for ~10 min and wipe off with a dry tissue. Let the plates dry. Mark the positions of the magnets, nuts and washers and paint all other surfaces with Hammerite or a similar anti rust paint. Lightly grease the bolts, the clearance holes, exposed iron and the nuts. Fully assemble one plate with bolts and finger tight nuts. Check that the other plate fits on cleanly and fully tighten the nuts. Fit a second nut on each bolt leaving about 3/4" thread between the nuts. Lightly grease and wipe the magnet mounting spaces. Separate a magnet, clean any dust or debris off it using gaffer sticky tape, apply it to the edge of the steel plate and slide it into position. Check that a second magnet has opposite top surface polarity and slide it into position. Check the orientation of the free plate and assemble opposite polarity magnets on it - a N/S magnet pair on one plate opposes S/N pair on the other. Slide the free plate onto the mounting bolts, recheck the magnet polarity, adjust the nuts to give the desired magnet gap separation and fit the lock nuts. Wipe off any excess grease. _http://www.amazingmagnets.com/_ (http://www.amazingmagnets.com/) and _http://www.kjmagnetics.com/_ (http://www.kjmagnetics.com/) in the US stock a wide range of NdFeB magnets amongst many other sources. Geoff, you raised the question of how great a S/N ratio you can get. My 16 bit ADC gives me a 90 dB range. When I was developing my LVDT sensor, I managed to get about 7 nano metre noise over a 6 mm linear movement with 10 Hz bandwidth. This is not far short of 120 dB. However, my local ambient ground noise is well over 10x this and it is strongly dependant on the weather, the local traffic and the time of day. This is my practical concern and it is the major limitation for a lot of 'amateur' systems. Many professional systems use deep boreholes remote from human activity. I agree with Dave on the desirability of burying geophones to reduce the pickup of surface noise. With a low noise geophone / coil type amplifier, you should be able to get quite a bit below 1 micro V input noise for 10 Hz bandwidth without using 'special' circuits. If you were prepared to build a chopper amplifier, you would likely get below 100 nano V. Roger Sparks commented on the presence of ocean microseisms masking small quakes. It is possible to use a twin Tee variable width bandstop filter to remove ~50 dB of this signal. The signals are usually quite narrow band, although they do vary in period around the world and with time. Regards, Chris Chapman

In a message dated 26/03/2006, gmvoeth@........... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>it is my=20 understanding you want the highest uniform magnetic field possible and you= =20 want the wires to move within that field perpendicular. So to compliment t= he=20 field you will put two horseshoe type magnets in opposition with a gap the= n=20 have
the coil in the middle with one half cutting the N/S poles and the= =20 other half cutting the S/N poles.
It seems best if the coil is smaller= =20 then the magnet
faces and is rectangular rather than=20 circular.

Hi Geoff, Ian,

If you=20 could get several of those old military magnetron magnets like they use=20= in=20 the old days of electronics that are used for Physics demonstrations tod= ay=20 at the universities you most probably would have the best magnet you can= =20 get. But they look like they weigh 100 lbs each.

They can be used but they are very bulky and=20 don't usually have the pole shape that you want.

You are much better off with rectangular coils=20 and rectangular magnets.

You need two adjacent areas of opposing high=20 intensity field. NdFeB bar magnets are not very expensive, but they are very= =20 powerful.

The 'I' is soft iron plate.

The 'B' are the support bolts with 3 off nuts=20 locking the plates in place.

The 'N' and 'S' are 1" square x 1/8" Neo magnet= s=20 with poles on the square face.

The 'CC-------CC' is a rectangular frame coil w= ith=20 an open centre and maybe 3,000 to 5,000 turns, about 1" wide by 1,1/4" long.= The=20 coil overlaps the ends of the magnets coming out of the paper. I used=20 4 paxolin rods and thin sheet held together with epoxy glue to make the= =20 coil frame. Make a reinforced hole in the centre so that you can mount the f= rame=20 on a bolt in a hand drill to wind on the wire.

Sensor. I have exaggerated the coil to magnet separation.

Magnets 1"squarex1/8" thick with poles on the square face

B &nbs= p; &n= bsp; = &nbs= p; &n= bsp; B

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII= IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

B &nbs= p; NNNNNNNNNNSSSSSSSSSS = B

B &nbs= p; &n= bsp; = &nbs= p; &n= bsp; B

B &nbs= p; =20 <- CC------------------CC =20 -> = ; B

B &nbs= p; CC------= ------------CC &n= bsp; B

B &nbs= p; &n= bsp; = &nbs= p; &n= bsp; B

B &nbs= p; =20 SSSSSSSSSSNNNNNNNNNN &n= bsp; =20 B

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII= IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

B &nbs= p; &n= bsp; = &nbs= p; &n= bsp; B

Damper. Cu is the wide copper damping plate, 1/16" to 1/8"=20 thick

Magnets 1"x1/2"widex1/4" thick with poles on the 1"x1/2" face

View shows the 1/2"x1/4" magnet ends

B &nbs= p; &n= bsp; 3.5" long &nbs= p; &n= bsp; B = ;=20 Mild Steel Plate

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII= IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII=20 1/4" thick x 2" wide

B &nbs= p; &n= bsp;NNNNNSSSSS &n= bsp; = B

B <-=20 CuCuCuCuCuCuCuCuCuCuCuCu -> B 1/4" mild ste= el=20 bolts

B &nbs= p; =20 SSSSSNNNNN = &nbs= p; =20 B full thread + 3 nuts

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII= IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

B &nbs= p; &n= bsp; = &nbs= p; &n= bsp; =20 B

For a Lehman, I use two 1/4" thick bright mild steel=20 plates, 3.5" long by 2" wide. The corners are drilled to take 1/4" mild stee= l=20 set screws 2.5" long with mild steel washers and nuts. The two plates a= re=20 held maybe 3/4" to 1" apart for a sensor, using three nuts on every bolt.=20 A bolt is firmly secured to one plate using a nut. The second plate is=20 mounted in between pairs of nuts on the free thread, to allow the separation= of=20 the plates to be adjusted and locked. Four NdFeB magnets 1/8" thick by 1" sq= uare=20 are mounted on the inside faces of the plates. A N+S pair on one face i= s=20 opposed by a S+N pair on the other. The sensor coil is mounted at the centre= of=20 the high intensity magnetic field.

For induced current damping, I=20 use four NdFeB bar magnets 1"x1/2"x1/4" thick in two opposing squa= res,=20 with the same 1/4" steel plate mounting, but with a much smaller magnet=20 separation. I use a copper damping plate, 1/16" to 1/8" thick as=20 appropriate, a bit over 2" wide and 2.5" free length. This allows=20= the=20 arm to swing +/-1/2" without the edge of the copper plate overlapping the ed= ge=20 of the 1" magnet square. The N+S join of the magnet pairs is set perpendicul= ar=20 to the direction of motion. The damping is adjusted by varying by the length= of=20 copper tongue overlapping the magnet square and also by varying the separati= on=20 of the 1/4" mild steel plates and hence the magnet separations. Most of the=20 damping occurs close to the central N/S magnet join. This is a very effectiv= e=20 and easily adjusted design of damper.

I have also used soft Al damping plates, but Al= is=20 usually more strongly paramagnetic than the copper is diamagnetic and it has= a=20 higher resistivity. I use the damping plate to physically limit the sideways= =20 travel of the seismometer arm. If the plate is made narrower and the arm dri= fts,=20 you may get 'odd' force effects as the edge of the plate gets close to=20= the=20 outside edge of the magnets. Al is usually mildly paramagnetic, but copper i= s=20 usually diamagnetic.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I can't=20 imagine how you could safely create a one inch gap with those monstrous=20 magnets. They would take off a finger or two if you were not careful in=20 keeping them apart.

With some difficulty and great care= !=20 Neo magnets start to get dangerous above about 1/4" thick, 1/2"=20 square. I have a pair 2" square by 1/2" thick. I can't put eno= ugh=20 finger force on them to even slide them apart. I use wood blocks=20 and an A frame work bench. Two of these magnets will 'jump=20 together' if less than about a foot apart. Only ever=20 handle ONE free magnet at a time!

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>No one=20 talks about safety when playing with springs and stuff so I guess no amate= urs=20 have had any serious accidents trying to build these=20 seismometers.

Oh yes they do! Sean's EMails carried several=20 warnings about dry wall scraper spring systems.

Construction.

Cut and file the 2"x1/4" bright mild steel to=20 length. Mark out the 3 or 4 bolt holes to choice on one plate, the= n=20 clamp the two plates together and drill all the clearance holes through= =20 both plates at the same time. Mark the plate orientation with a centre=20 punch. This ensures perfect bolt alignment. Degrease, then coat the ste= el=20 with acid anti rust liquid / paste, leave for ~10 min and wipe off with= a=20 dry tissue. Let the plates dry. Mark the positions of the magnets,=20 nuts and washers and paint all other surfaces with Hammerit= e or=20 a similar anti rust paint.

Lightly grease the bolts, the clearance holes,=20 exposed iron and the nuts. Fully assemble one plate with bolts and fing= er=20 tight nuts. Check that the other plate fits on cleanly and fully tighten the= =20 nuts. Fit a second nut on each bolt leaving about 3/4" thread between the nu= ts.=20

Lightly grease and wipe the magnet mounting spa= ces.=20 Separate a magnet, clean any dust or debris off it using gaffer sticky tape,= =20 apply it to the edge of the steel plate and slide it into position. Check th= at a=20 second magnet has opposite top surface polarity and slide it into position.=20 Check the orientation of the free plate and assemble opposite polarity magne= ts=20 on it - a N/S magnet pair on one plate opposes S/N pair on the other.

Slide the free plate onto the mounting bolts,=20 recheck the magnet polarity, adjust the nuts to give the desired magnet gap=20 separation and fit the lock nuts. Wipe off any excess grease.

http://www.amazingmagnets.com/&n= bsp;=20 and http://www.kjmagnetics.com/ in= the=20 US stock a wide range of NdFeB magnets amongst many other sources.

Geoff, you raised the question of how great a S= /N=20 ratio you can get. My 16 bit ADC gives me a 90 dB range. When I was=20 developing my LVDT sensor, I managed to get about 7 nano metre noise ov= er a=20 6 mm linear movement with 10 Hz bandwidth. This is not far short of 120= dB.=20 However, my local ambient ground noise is well over 10x this and it is stron= gly=20 dependant on the weather, the local traffic and the time of day. T= his=20 is my practical concern and it is the major limitation for a lot of 'amateur= '=20 systems. Many professional systems use deep boreholes remote from human=20 activity. I agree with Dave on the desirability of burying geophones to= =20 reduce the pickup of surface noise.

With a low noise geophone / coil type amplifier= ,=20 you should be able to get quite a bit below 1 micro V input noise for 10 Hz=20 bandwidth without using 'special' circuits. If you were prepared to build a=20 chopper amplifier, you would likely get below 100 nano V.

Roger Sparks commented on the presence of ocean= =20 microseisms masking small quakes. It is possible to use a twin Tee variable=20 width bandstop filter to remove ~50 dB of this signal. The signals are=20 usually quite narrow band, although they do vary in period around the world=20= and=20 with time.

Regards,

Chris Chapman

Subject: Re: Sensor and Damping magnets From: "James Hannon" jmhannon@......... Date: Mon, 27 Mar 2006 07:41:13 -0600 Here is another good place to buy magnets. http://www.forcefieldmagnets.com/catalog/ Jim Hannon -- Jim Hannon http://www.fmtcs.com/web/jmhannon/ 42,11.90N,91,39.26W WB0TXL -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Sensor and Damping magnets From: ChrisAtUpw@....... Date: Mon, 27 Mar 2006 11:46:53 EST In a message dated 27/03/2006, jmhannon@......... writes: Here is another good place to buy magnets. http://www.forcefieldmagnets.com/catalog/ Hi Jim, They used to be quite good and inexpensive. However, they now only stock the 0033 1"x1/2"x1/4" magnet size, not the 1" square x1/8". For these they want $3+pp each and they only have 39 in stock. Looking at their copper wire they want $18 for a 1lb reel of 36 awg and they only have 4 reels in stock. This is 13,219 ft at 423 Ohm /1000 ft. They have 6 of the 34awg reels @ $17, 8,310 ft at 266 ohms / 1000 ft. You might need a bit over 1,500 ft for a coil. _http://www.kjmagnetics.com/_ (http://www.kjmagnetics.com/) have to 1"x1/2"x1/4" BX084 magnets 4off @ $7.95 and the 1"square x1/8" BX0X02 magnets 4off @ $12.45 When I make suggestions for suppliers, I do try to check that they have the products available and at a 'market' price. Regards, Chris Chapman

In a message dated 27/03/2006, jmhannon@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Here is=20 another good place to buy=20 magnets.
http://www.forcefieldmagnets.com/catalog/

Hi Jim,

They used to be quite good and inexpensive.=20 However, they now only stock the 0033 1"x1/2"x1/4" magnet size, not the 1"=20 square x1/8". For these they want $3+pp each and they only have 39 in stock.= =20

Looking at their copper wire they want $18 for=20= a=20 1lb reel of 36 awg and they only have 4 reels in stock. This is 13,219=20= ft=20 at 423 Ohm /1000 ft. They have 6 of the 34awg reels @ $17, 8,310 ft at= 266=20 ohms / 1000 ft. You might need a bit over 1,500 ft for a coil.

http://www.kjmagnetics.com/ ha= ve to=20 1"x1/2"x1/4" BX084 magnets 4off @ $7.95 and the 1"square x1/8" BX0X02 magnet= s=20 4off @ $12.45

When I make suggestions for suppliers, I do try= to=20 check that they have the products available and at a 'market' price.

Regards,

Chris Chapman

Subject: Re: Sensor and Damping magnets From: "James Hannon" jmhannon@......... Date: Mon, 27 Mar 2006 10:54:51 -0600 Things must have changed. I haven't done any comparisons lately but when I did I thought they had good prices on the magnets. Sorry, Jim Hannon ---------- Original Message ---------------------------------- From: ChrisAtUpw@....... Reply-To: psn-l@.............. Date: Mon, 27 Mar 2006 11:46:53 EST > >In a message dated 27/03/2006, jmhannon@......... writes: > >Here is another good place to buy magnets. >http://www.forcefieldmagnets.com/catalog/ > > > >Hi Jim, > > They used to be quite good and inexpensive. However, they now only stock >the 0033 1"x1/2"x1/4" magnet size, not the 1" square x1/8". For these they >want $3+pp each and they only have 39 in stock. > Looking at their copper wire they want $18 for a 1lb reel of 36 awg and >they only have 4 reels in stock. This is 13,219 ft at 423 Ohm /1000 ft. They >have 6 of the 34awg reels @ $17, 8,310 ft at 266 ohms / 1000 ft. You might >need a bit over 1,500 ft for a coil. > > _http://www.kjmagnetics.com/_ (http://www.kjmagnetics.com/) have to >1"x1/2"x1/4" BX084 magnets 4off @ $7.95 and the 1"square x1/8" BX0X02 magnets >4off @ $12.45 > When I make suggestions for suppliers, I do try to check that they have >the products available and at a 'market' price. > > Regards, > > Chris Chapman > > -- Jim Hannon http://www.fmtcs.com/web/jmhannon/ 42,11.90N,91,39.26W WB0TXL -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Sensor and Damping magnets From: ian ian@........... Date: Mon, 27 Mar 2006 18:10:07 +0100 I got mine from ebay... Real cheap too! Ian James Hannon wrote: >Things must have changed. I haven't done any comparisons lately but when I did I thought they had good prices on the magnets. > >Sorry, >Jim Hannon > > >---------- Original Message ---------------------------------- >From: ChrisAtUpw@....... >Reply-To: psn-l@.............. >Date: Mon, 27 Mar 2006 11:46:53 EST > > > >>In a message dated 27/03/2006, jmhannon@......... writes: >> >>Here is another good place to buy magnets. >>http://www.forcefieldmagnets.com/catalog/ >> >> >> >>Hi Jim, >> >> They used to be quite good and inexpensive. However, they now only stock >>the 0033 1"x1/2"x1/4" magnet size, not the 1" square x1/8". For these they >>want $3+pp each and they only have 39 in stock. >> Looking at their copper wire they want $18 for a 1lb reel of 36 awg and >>they only have 4 reels in stock. This is 13,219 ft at 423 Ohm /1000 ft. They >>have 6 of the 34awg reels @ $17, 8,310 ft at 266 ohms / 1000 ft. You might >>need a bit over 1,500 ft for a coil. >> >> _http://www.kjmagnetics.com/_ (http://www.kjmagnetics.com/) have to >>1"x1/2"x1/4" BX084 magnets 4off @ $7.95 and the 1"square x1/8" BX0X02 magnets >>4off @ $12.45 >> When I make suggestions for suppliers, I do try to check that they have >>the products available and at a 'market' price. >> >> Regards, >> >> Chris Chapman >> >> >> >> > >-- >Jim Hannon >http://www.fmtcs.com/web/jmhannon/ >42,11.90N,91,39.26W >WB0TXL >-- >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > > > I got mine from ebay... Real cheap too!

Ian

James Hannon wrote:

Things must have changed. I haven't done any comparisons lately but when I did I thought they had good prices on the magnets. 

Sorry,
Jim Hannon

---------- Original Message ----------------------------------
From: ChrisAtUpw@.......
Reply-To: psn-l@..............
Date:  Mon, 27 Mar 2006 11:46:53 EST

In a message dated 27/03/2006, jmhannon@......... writes:

Here is  another good place to buy  magnets.
http://www.forcefieldmagnets.com/catalog/



Hi Jim,

   They used to be quite good and inexpensive.  However, they now only stock 
the 0033 1"x1/2"x1/4" magnet size, not the 1"  square x1/8". For these they 
want $3+pp each and they only have 39 in stock. 
   Looking at their copper wire they want $18 for a  1lb reel of 36 awg and 
they only have 4 reels in stock. This is 13,219 ft  at 423 Ohm /1000 ft. They 
have 6 of the 34awg reels @ $17,  8,310 ft at 266  ohms / 1000 ft. You might 
need a bit over 1,500 ft for a coil.

   _http://www.kjmagnetics.com/_ (http://www.kjmagnetics.com/)  have to  
1"x1/2"x1/4" BX084 magnets 4off @ $7.95 and the 1"square x1/8" BX0X02 magnets  
4off @ $12.45 
   When I make suggestions for suppliers, I do try to  check that they have 
the products available and at a 'market' price.

   Regards,

   Chris Chapman


--
Jim Hannon
http://www.fmtcs.com/web/jmhannon/
42,11.90N,91,39.26W
WB0TXL
--
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Subject: Re: Sensor and Damping magnets From: Bobhelenmcclure@....... Date: Mon, 27 Mar 2006 14:54:12 EST I highly recommend the following magnets: _http://www.gaussboys.com_ (http://www.gaussboys.com) Block #18 Shape: Block Size: 50mm x 18mm x 6mm Plating: Nickel Surface Gauss: 2900 Material Grade: N38 Strength: 70 lbs Price: $5.00 each Place pairs on quarter-inch or thicker steel plates and hold the plates apart with stove bolts. Assemble very carefully, using a thick shim to hold the gap, and then jack the gap open with the bolts to release the shim. Wear heavy gloves! For a gap of 0.250 inches, you get a field of 8000 gauss. A rectangular coil of 1100 turns yields 85v-s/m output. You won't need separate damping magnets. A shunt resistor will provide the damping. Bob

I highly recommend the following magnets:

http://www.gaussboys.com
Bl= ock=20 #18
Shape: Block
Size: 50mm x 18mm x 6mm
Plating: Nickel
Sur= face=20 Gauss: 2900
Material Grade: N38
Strength: 70 lbs
Price: $5.00=20 each

Place pairs on quarter-inch or thicker steel plates and hold the plates= =20 apart with stove bolts. Assemble very carefully, using a thick shim to hold=20= the=20 gap, and then jack the gap open with the bolts to release the shim. Wear hea= vy=20 gloves! For a gap of 0.250 inches, you get a field of 8000 gauss. A rectangu= lar=20 coil of 1100 turns yields 85v-s/m output. You won't need separate damping=20 magnets. A shunt resistor will provide the damping.

Bob

Subject: Weeks or month system ? From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Mon, 27 Mar 2006 22:32:15 +0000 Hi all I am wondering if it is better for me to put the files with the earthquakes that i record in week long system or a month long type of system like i have now. I am wondering about this becose i will get more then a 100 files (z,n,e channels) in one folder if i have it in a month type system. I am also unsure how well winquake is going to handle huge number of files. Becose one day i will see a massive earthquake swarm and record large number of earthquakes. I also wonder what system other pepole here have on earthquake recordings time and dates. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Sensor and Damping magnets From: ChrisAtUpw@....... Date: Mon, 27 Mar 2006 22:47:04 EST In a message dated 27/03/2006, Bobhelenmcclure@....... writes: Place pairs on quarter-inch or thicker steel plates and hold the plates apart with stove bolts. Assemble very carefully, using a thick shim to hold the gap, and then jack the gap open with the bolts to release the shim. Wear heavy gloves! For a gap of 0.250 inches, you get a field of 8000 gauss. A rectangular coil of 1100 turns yields 85v-s/m output. You won't need separate damping magnets. A shunt resistor will provide the damping. Hi Bob, What are 'stove bolts' please? You may need rather thicker plate than 1/4" with two side by side 18 mm x 6 mm thick magnets. The 5 mm plate that I used at first was only just thick enough to take the flux of the 1/2" x 1/4" thick magnets. Are you using a pair of magnets on one plate and then putting a bare iron plate over the top, or do you use four magnets on two plates? I have found using four magnets gives a more constant central field. It also allows a bit more thread to fit the two central nuts. The reason why I do not use this sort of damping is that I want the damping and the sensitivity to be independent. The damping that you need is a function of the period. Setting up a system where the sensitivity and the damping are both a function of the period is a bit more difficult the second time. I use the wide copper damping plate as a mechanical stop. The plate edge can never move into the high field region at the edge of the magnets. If your coil drifted off the magnet, the damping would go to zero. I have also had some variable force effects when the copper wire is close to the edge of a magnet. Not all copper wire seems to have the same diamagnetic properties. Is the 85V/m/sec figure correct? It does not sound very high. Regards, Chris Chapman

In a message dated 27/03/2006, Bobhelenmcclure@....... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>

Place pairs on quarter-inch or thicker steel plates and hold the plat= es=20 apart with stove bolts. Assemble very carefully, using a thick shim to hol= d=20 the gap, and then jack the gap open with the bolts to release the shim. We= ar=20 heavy gloves! For a gap of 0.250 inches, you get a field of 8000 gauss. A=20 rectangular coil of 1100 turns yields 85v-s/m output. You won't need separ= ate=20 damping magnets. A shunt resistor will provide the=20 damping.

Hi Bob,

What are 'stove bolts' please?

You may need rather thicker plate than 1/4" wit= h=20 two side by side 18 mm x 6 mm thick magnets. The 5 mm plate that I used= at=20 first was only just thick enough to take the flux of the 1/2" x 1/4" thick=20 magnets.

Are you using a pair of magnets on one plate an= d=20 then putting a bare iron plate over the top, or do you use four magnets= on=20 two plates? I have found using four magnets gives a more constant central fi= eld.=20 It also allows a bit more thread to fit the two central nuts.

The reason why I do not use this sort of dampin= g is=20 that I want the damping and the sensitivity to be independent. The damping t= hat=20 you need is a function of the period. Setting up a system where the sensitiv= ity=20 and the damping are both a function of the period is a bit more difficult th= e=20 second time.

I use the wide copper damping plate as a mechan= ical=20 stop. The plate edge can never move into the high field region at the e= dge=20 of the magnets. If your coil drifted off the magnet, the damping would=20= go=20 to zero. I have also had some variable force effects when the copper wire is= =20 close to the edge of a magnet. Not all copper wire seems to have the sa= me=20 diamagnetic properties.

Is the 85V/m/sec figure correct? It does not so= und=20 very high.

Regards,

Chris Chapman

Subject: RE: Sensor and Damping magnets From: "Jack Ivey" ivey@.......... Date: Tue, 28 Mar 2006 09:51:45 -0500 Chris, =20 >The 5 mm plate that I used at first was only just thick enough to take the flux of the 1/2" x 1/4" thick magnets. Did you calculate this or measure it somehow? =20 Thanks, Jack

Chris,

>The 5 mm plate = that I used at first was only just thick enough to take the flux of the = 1/2" x 1/4" thick magnets.

Did you calculate this or measure = it somehow?

Thanks,

Jack

Subject: Re: Sensor and Damping magnets From: Bobhelenmcclure@....... Date: Tue, 28 Mar 2006 16:54:23 EST Hi Chris, Take a look at _http://www.jclahr.com/science/psn/mcclure/horiz.html_ (http://www.jclahr.com/science/psn/mcclure/horiz.html) for my magnet design. This page shows different sized magnets, but 2" by 3" by 1/4" steel plates for the Gaussboys blk18 magnets work ok, with only slight saturation. I have no problems with sensitivity vs damping. My coil resistance is 340 ohms, and critical damping is achieved with ~25,000 ohms shunt resistance. Regarding output sensitivity, the formula is V=BLnv, where B is magnetic field in Teslas, L is the effective length of wire per turn (in meters) cutting the magnetic field lines, n is the number of turns, and v is the velocity, in meters per second. The L per turn is twice the length of the Gaussboys magnets , so L=0.1m. Let n=1100, B=0.8T, and v=1.0 m/s. This gives a sensitivity of 88v-s/m. The biggest problem I have with this design is the diamagnetism of the copper wire. Having a core of acrylic plastic for the coil and an outer plate of acrylic plastic helps to reduce net diamagnetic force on the coil assembly, since the plastic is also diamagnetic. Bob

Hi Chris,

Take a look at

http://www.jcl= ahr.com/science/psn/mcclure/horiz.html

for my magnet design. This page shows different sized magnets, but 2" b= y 3"=20 by 1/4" steel plates for the Gaussboys blk18 magnets work ok, with only slig= ht=20 saturation.

I have no problems with sensitivity vs damping. My coil resistan= ce=20 is 340 ohms, and critical damping is achieved with ~25,000 ohms shunt=20 resistance.

Regarding output sensitivity, the formula is V=3DBLnv, where B i= s=20 magnetic field in Teslas, L is the effective length of wire per turn (in met= ers)=20 cutting the magnetic field lines, n is the number of turns, and v is the=20 velocity, in meters per second.

The L per turn is twice the length of the Gaussboys magnets , so= =20 L=3D0.1m. Let n=3D1100, B=3D0.8T, and v=3D1.0 m/s. This gives a sensitivity=20= of=20 88v-s/m.

The biggest problem I have with this design is the diamagnetism=20= of=20 the copper wire. Having a core of acrylic plastic for the coil and an outer=20 plate of acrylic plastic helps to reduce net diamagnetic force on the coil=20 assembly, since the plastic is also diamagnetic.

Bob

Subject: Re: Sensor and Damping magnets From: ChrisAtUpw@....... Date: Tue, 28 Mar 2006 17:30:42 EST In a message dated 28/03/2006, Bobhelenmcclure@....... writes: The biggest problem I have with this design is the diamagnetism of the copper wire. Having a core of acrylic plastic for the coil and an outer plate of acrylic plastic helps to reduce net diamagnetic force on the coil assembly, since the plastic is also diamagnetic. Hi Bob, Not all Copper wire is diamagnetic! It was because I had noticed force effects when windings were near or over the edges of the magnets that I used the 1" square magnets and the narrower coils. Regards, Chris

In a message dated 28/03/2006, Bobhelenmcclure@....... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 biggest problem I have with this design is the diamagnetism of the copper=20 wire. Having a core of acrylic plastic for the coil and an outer plate of=20 acrylic plastic helps to reduce net diamagnetic force on the coil assembly= ,=20 since the plastic is also diamagnetic.

Hi Bob,

Not all Copper wire is diamagnetic! It was beca= use=20 I had noticed force effects when windings were near or over the edges o= f=20 the magnets that I used the 1" square magnets and the narrower coils.

Regards,

Chris

Subject: RE: Sensor and Damping magnets From: "Jack Ivey" ivey@.......... Date: Tue, 28 Mar 2006 17:38:45 -0500 >The biggest problem I have with this design is the diamagnetism of the copper wire.=20 =20 How does this manifest itself? Does the coil get pushed out of the slot? =20 >Having a core of acrylic plastic for the coil and an outer plate of acrylic plastic helps to reduce net diamagnetic force on the=20 >coil assembly, since the plastic is also diamagnetic. =20 How does this help? =20 Thanks, Jack

>The biggest problem I have with this design is the = diamagnetism of the copper wire.

How does this manifest = itself? Does the coil get pushed out of the slot?

>Having a core of acrylic plastic for the coil and an outer = plate of acrylic plastic helps to reduce net diamagnetic force on the =

>coil assembly, since the plastic is also = diamagnetic.

How does this = help?

Thanks,

Jack

>The biggest problem I have with this design is the = diamagnetism of the copper wire.

How does this manifest = itself? Does the coil get pushed out of the slot?

>Having a core of acrylic plastic for the coil and an outer = plate of acrylic plastic helps to reduce net diamagnetic force on the =

>coil assembly, since the plastic is also = diamagnetic.

How does this = help?

Thanks,

Jack

Subject: Geophone and long time of vibrations From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Tue, 28 Mar 2006 23:49:32 +0000 Hi all What does long period of vibrations from wind and ocen wave have on the geophone type that i have. I am wondering about the effects becose there is going to be hig wind for the next few days due to a storm that is passing over Iceland. I don't plan to take the geophone offline. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophone and long time of vibrations From: ChrisAtUpw@....... Date: Tue, 28 Mar 2006 19:17:00 EST In a message dated 29/03/2006, jonfr500@......... writes: What does long period of vibrations from wind and ocean wave have on the geophone type that i have. I am wondering about the effects because there is going to be high wind for the next few days due to a storm that is passing over Iceland. I don't plan to take the geophone offline. Hi Jon, Generally a large increase in the background noise. You may also see particular frequencies excited due to buildings, cavities like corridors, ventilation shafts, vertical poles.... increased sea waves.... You don't have trees do you? Regards, Chris Chapman

In a message dated 29/03/2006, jonfr500@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>What=20 does long period of vibrations from wind and ocean wave have on=20 the
geophone type that i have. I am wondering about the effects because= =20 there
is going to be high wind for the next few days due to a storm tha= t=20 is
passing over Iceland. I don't plan to take the geophone=20 offline.

Hi Jon,

Generally a large increase in the background no= ise.=20 You may also see particular frequencies excited due to buildings, cavities l= ike=20 corridors, ventilation shafts, vertical poles.... increased sea waves.... Yo= u=20 don't have trees do you?

Regards,

Chris Chapman

Subject: Re: Geophone and long time of vibrations From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Wed, 29 Mar 2006 00:26:51 +0000 Hi Chris I did type this in wrong. What i ment what effect does long perid vibration have on the geophone componment, the coil, springs and so on. I know about the background noise, it is clearly visable on my online graphs at the moment. But this is going to be long and hig frequancy vibration becose of the wind and problay for some part of the ocen wave hitting the beach. There are not many trees near the house. There are few, but nothing that sheilds the house from the wind. > Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophone and long time of vibrations From: ChrisAtUpw@....... Date: Tue, 28 Mar 2006 20:51:12 EST In a message dated 29/03/2006, jonfr500@......... writes: What i meant what effect does long period vibration have on the geophone component, the coil, springs and so on. But this is going to be long and high frequency vibration because of the wind and problem for some part of the ocean wave hitting the beach. Hi Jon, It is very unlikely indeed to damage your geophones. Your house would probably blow away first..! There are not many trees near the house. There are few, but nothing that shields the house from the wind. It is not the shielding that matters, but the swaying coupled to the ground via the roots. Regards, Chris Chapman

In a message dated 29/03/2006, jonfr500@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>What i=20 meant what effect does long period
vibration have on the geophone=20 component, the coil, springs and so on.
But this is going to be long an= d=20 high frequency
vibration because of the wind and problem for some part=20= of=20 the ocean wave
hitting the beach.

Hi Jon,

It is very unlikely indeed to damage your=20 geophones. Your house would probably blow away first..!

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>There=20 are not many trees near the house. There are few, but nothing that
shie= lds=20 the house from the wind.

It is not the shielding that matters, but the=20 swaying coupled to the ground via the roots.

Regards,

Chris Chapman

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>

Subject: Re: Sensor and Damping magnets From: ChrisAtUpw@....... Date: Tue, 28 Mar 2006 20:59:10 EST In a message dated 28/03/2006, ivey@.......... writes: Chris, >The 5 mm plate that I used at first was only just thick enough to take the flux of the 1/2" x 1/4" thick magnets. Did you calculate this or measure it somehow? Thanks, Jack Hi Jack, I did both. You can look up the flux densities of the magnets and the Bm saturation for mild steel. If you want to get very low leakage flux, all the flux has to go sideways through the mild steel plate. In my design, I allow a 1/2" border around the periphery of the magnets for the internal field to spread out and also to catch stray flux. You get a flux concentration near the magnet join and field from the edges of the magnets themselves. I also mounted various arrangements of magnets on one side of a larger mild steel plate and then used a transformer lamination strip suspended with cellotape on the other side to check if there was any field penetration. With the 5 mm plate and 20x10x5 mm magnet pairs, there was no effect. With 20x20x5 mm magnets there was a small joint area which attracted the strip. Going to 1"x1/2"x1/4" magnet pairs, I could just detect some attraction. Doubling it up to 1"x1"x1/4" magnet pairs produced a fairly strong attraction area. In contrast, the 1"squarex1/8" sensor magnet pairs seemed OK. I chose 1/4" mild steel (6.35 mm) with the 1"x1/2"x1/4" magnet pairs. I may be being 'a bit fussy', but I don't want any stray field about and I do want the maximum field in the magnet gap. Using mild steel bolts to secure the plates was of considerable help - no two magnets have an identical flux and I am using 4 off ! I was satisfied the this was 'good enough'. The maximum damping effect is near the central join. To get maximum damping the copper plate needs to overlap both ends of the 1" magnet square by about 1/2". Regards, Chris Chapman

In a message dated 28/03/2006, ivey@.......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>

Chris,

<= /FONT>>The 5 mm plate= that=20 I used at first was only just thick enough to take the flux of the 1/2" x=20= 1/4"=20 thick magnets.

= Did you calculate this or measure i= t=20 somehow?

Thanks,

Jack

Hi Jack,

I did both. You can look up the flux densities=20= of=20 the magnets and the Bm saturation for mild steel. If you want to get very lo= w=20 leakage flux, all the flux has to go sideways through the mild steel plate.=20= In=20 my design, I allow a 1/2" border around the periphery of the magnets fo= r=20 the internal field to spread out and also to catch stray flux. You= get=20 a flux concentration near the magnet join and field from the edges of the=20 magnets themselves.

I also mounted various arrangements of mag= nets=20 on one side of a larger mild steel plate and then used a transform= er=20 lamination strip suspended with cellotape on the other side to check if= =20 there was any field penetration. With the 5 mm plate and 20x10x5 mm magnet=20 pairs, there was no effect. With 20x20x5 mm magnets there was a small joint=20= area=20 which attracted the strip. Going to 1"x1/2"x1/4" magnet pairs, I could just=20 detect some attraction. Doubling it up to 1"x1"x1/4" magnet pairs produced a= =20 fairly strong attraction area. In contrast, the 1"squarex1/8" sensor ma= gnet=20 pairs seemed OK.

I chose 1/4" mild steel (6.35 mm) with the=20 1"x1/2"x1/4" magnet pairs. I may be being 'a bit fussy', but I don't wa= nt=20 any stray field about and I do want the maximum field in the magnet gap. Usi= ng=20 mild steel bolts to secure the plates was of considerable help - no two magn= ets=20 have an identical flux and I am using 4 off ! I was satisfied the this was '= good=20 enough'.

The maximum damping effect is near the=20 central join. To get maximum damping the copper plate needs to overlap=20= both=20 ends of the 1" magnet square by about 1/2".

Regards,

Chris Chapman

Subject: Re: Sensor and Damping magnets From: Bobhelenmcclure@....... Date: Tue, 28 Mar 2006 23:58:31 EST Chris-- =20 I purchased #38 wire (Low temperature (105=B0C, NEMA STD MW-1-c) enamel=20 coated magnet wire) on quarter-pound spools for $7.50 off from Alltronics.c= om. It=20 is diamagnetic. I believe that if a wire is fabricated from OFHC copper, it= =20 will be diamagnetic, but I do not know anything about this particular wire=20 except that it is cheap and has a very low temperature rating. =20 In an attempt to answer Jack Ivey's question, a diamagnetic coil in my 4=20 pole magnet structure experiences a decentering force, which makes stable=20 adjustment of natural period very difficult. Imbedding the coil in a thick=20 diamagnetic sheet of plastic of transverse dimensions larger than the magne= tic=20 field region reduces the diamagnetic pull exerted on the coil by the gradie= nts of=20 the field reversal and the edge fields of the magnet. =20 Bob

Chris--

I purchased #38 wire (Low temperatur= e=20 (105=B0C, NEMA STD MW-1-c) enamel coated magnet wire) on quarter-poun= d=20 spools for $7.50 off from Alltronics.com. It is diamagnetic. I believe that=20= if a=20 wire is fabricated from OFHC copper, it will be diamagnetic, but I do not kn= ow=20 anything about this particular wire except that it is cheap and has a very l= ow=20 temperature rating.

In an attempt to answer Jack Ivey's question, a=20 diamagnetic coil in my 4 pole magnet structure experiences a decentering for= ce,=20 which makes stable adjustment of natural period very difficult. Imbeddi= ng=20 the coil in a thick diamagnetic sheet of plastic of transverse dimensions la= rger=20 than the magnetic field region reduces the diamagnetic pull exerted on the c= oil=20 by the gradients of the field reversal and the edge fields of the magnet.

Bob

Subject: 2006 SF Quake From: Richard Webb dwebb002@............. Date: Wed, 29 Mar 2006 17:31:11 -0500 Hi, The SSA is having the 2006 meeting in SF the week of April 17. Are any PSN types going to be there? Dick Raleigh, NC __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: l15b 4.5 Geophone, detecting teleseismic earthquake From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr500@......... Date: Fri, 31 Mar 2006 02:18:48 +0000 Hi all Is it impossible for l15b 4.5Hz geophone to detect teleseismic earthquakes or just improbable. I am not sure of this yet, but i think that i did detect the Iran earthquake that did happen today at 01:17, 31 Mars 2006, it was 5.7mb in size based on data from emsc-csem. It was visable at Icelandic Met Office stations on 2Hz and somewhat above and below frequancyes, according to tremor plots on there website. Regards. -- J�n Fr�mann J�nsson http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: L15B 4.5 Geophone, detecting teleseismic earthquake From: ChrisAtUpw@....... Date: Thu, 30 Mar 2006 21:57:46 EST In a message dated 31/03/2006, jonfr500@......... writes: Is it impossible for L15B 4.5Hz geophone to detect teleseismic earthquakes or just improbable. Hi Jon, The sensitivity is down to ~1/5 at 2 Hz and it falls off increasingly rapidly below this. At 1 Hz it is ~1/20. So what you can see depends on the P wave frequency and on the magnitude of the quake. I would say that it may be 'difficult'. It is possible to use a 'Roberts type' frequency compensating amplifier to boost the output of a 4.5 Hz geophone fairly level down to ~0.5 Hz. This enables you to use these geophones fairly well for teleseismic quakes. Regards, Chris Chapman

In a message dated 31/03/2006, jonfr500@......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Is it=20 impossible for L15B 4.5Hz geophone to detect teleseismic
earthquakes or= =20 just improbable.

Hi Jon,

The sensitivity is down to ~1/5 at 2 Hz and it=20 falls off increasingly rapidly below this. At 1 Hz it is ~1/20. So what you=20= can=20 see depends on the P wave frequency and on the magnitude of the quake.=20= I=20 would say that it may be 'difficult'.

It is possible to use a 'Roberts type' frequenc= y=20 compensating amplifier to boost the output of a 4.5 Hz geophone fairly level= =20 down to ~0.5 Hz. This enables you to use these geophones fairly well fo= r=20 teleseismic quakes.

Regards,

Chris Chapman

Subject: Re: 2006 SF Quake From: John or Jan Lahr JohnJan@........ Date: Thu, 30 Mar 2006 20:25:36 -0800 I'll be attending the meeting. Maybe we should have an informal PSN meeting one evening? Tuesday or Wednesday would be the best for me. (April 18 or 19). Cheers, John At 02:31 PM 3/29/2006, you wrote: >Hi, > >The SSA is having the 2006 meeting in SF the week of April 17. Are >any PSN types going to be there? > >Dick >Raleigh, NC >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body >of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: L15B 4.5 Geophone, detecting teleseismic earthquake From: "Kareem at HeyJooJoo" system98765@............. Date: Thu, 30 Mar 2006 20:45:16 -0800 Hi Chris (& everyone else), Where can one get more information about the 'Roberts Amplifyer'? Kareem -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Thursday, March 30, 2006 6:58 PM To: psn-l@.............. Subject: Re: L15B 4.5 Geophone, detecting teleseismic earthquake In a message dated 31/03/2006, jonfr500@......... writes: Is it impossible for L15B 4.5Hz geophone to detect teleseismic earthquakes or just improbable. Hi Jon, The sensitivity is down to ~1/5 at 2 Hz and it falls off increasingly rapidly below this. At 1 Hz it is ~1/20. So what you can see depends on the P wave frequency and on the magnitude of the quake. I would say that it may be 'difficult'. It is possible to use a 'Roberts type' frequency compensating amplifier to boost the output of a 4.5 Hz geophone fairly level down to ~0.5 Hz. This enables you to use these geophones fairly well for teleseismic quakes. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: speaking about bad luck From: ian ian@........... Date: Fri, 31 Mar 2006 06:07:30 +0100 it used to (and still does) happen to me all the time. So much so that some people have asked me to warn them when my seismometer is off! I missed the Boxing day quake in Indonesia for instance. Ian J�n Fr�mann wrote: >Hi all > >I had a really bad luck today. As i told you in my email early today i >had a psu failure in the computer that records earthquakes for me. But >also today there was a earthquake that was 4.5Mb on the Reykjanes ridge, >it was felt in Reykjavik. More info here, >http://www.emsc-csem.org/index.php?page=current&sub=detail&id=HP408;2006 > >But becose my earthquake computer is down i didn't record this >earthquake. :( > >I really hate it when something like this happens. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: speaking about bad luck From: ian ian@........... Date: Fri, 31 Mar 2006 06:07:30 +0100 it used to (and still does) happen to me all the time. So much so that some people have asked me to warn them when my seismometer is off! I missed the Boxing day quake in Indonesia for instance. Ian J�n Fr�mann wrote: >Hi all > >I had a really bad luck today. As i told you in my email early today i >had a psu failure in the computer that records earthquakes for me. But >also today there was a earthquake that was 4.5Mb on the Reykjanes ridge, >it was felt in Reykjavik. More info here, >http://www.emsc-csem.org/index.php?page=current&sub=detail&id=HP408;2006 > >But becose my earthquake computer is down i didn't record this >earthquake. :( > >I really hate it when something like this happens. > >Regards. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 2006 SF Quake From: Richard Webb dwebb002@............. Date: Fri, 31 Mar 2006 08:59:29 -0500 John, I think an informal get together on either day would be great. Dick John or Jan Lahr wrote: > I'll be attending the meeting. Maybe we should have an informal PSN > meeting one evening? > Tuesday or Wednesday would be the best for me. (April 18 or 19). > > Cheers, > John > > At 02:31 PM 3/29/2006, you wrote: >> Hi, >> >> The SSA is having the 2006 meeting in SF the week of April 17. Are >> any PSN types going to be there? >> >> Dick >> Raleigh, NC >> __________________________________________________________ >> >> Public Seismic Network Mailing List (PSN-L) >> >> To leave this list email PSN-L-REQUEST@.............. with the body >> of the message (first line only): unsubscribe >> See http://www.seismicnet.com/maillist.html for more information. > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: L15B 4.5 Geophone, detecting teleseismic earthquake From: ChrisAtUpw@....... Date: Fri, 31 Mar 2006 10:26:37 EST In a message dated 31/03/2006, system98765@............. writes: Hi Chris (& everyone else), Where can one get more information about the 'Roberts Amplifier'? Kareem Hi Kareem, Go to _http://psn.quake.net/bibliography.html_ (http://psn.quake.net/bibliography.html) Roberts, PM "A Versatile Equilization Circuit for Increasing Seismometer Velocity Response Below the Natural Frequency." (for 4.5Hz geophones) BSSA, vol 79, pp 1607-1617 Oct. 1989 Your local library should be able to get you a photocopy. I made some simple circuit changes which reduced the very low frequency noise, if anyone is interested. The modified circuit seems to work fine. Lennartz use geophone compensators of this general type on their professional range. You get about a factor of 10 reduction in the minimum frequency - e.g. a 4.5Hz geophone will reproduce ~flat down to 0.45Hz. This enables you to pick up teleseismic quakes as well as local and regional ones. Regards, Chris Chapman

In a message dated 31/03/2006, system98765@............. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Hi Chris=20 (& everyone else),
Where can one get more information about the=20 'Roberts Amplifier'?
Kareem

Hi Kareem,

Go to http://psn.quake.net/bibliog= raphy.html

Roberts, PM "A Versatile Equilization Circuit f= or=20 Increasing Seismometer Velocity Response Below the Natural Frequency." (for=20 4.5Hz geophones) BSSA, vol 79, pp 1607-1617 Oct. 1989

Your local library should be able to get you a=20 photocopy.

I made some simple circuit changes which reduce= d=20 the very low frequency noise, if anyone is interested. The modified circuit=20 seems to work fine. Lennartz use geophone compensators of this general type=20= on=20 their professional range. You get about a factor of 10 reduction in the mini= mum=20 frequency - e.g. a 4.5Hz geophone will reproduce ~flat down to 0.45Hz. This=20 enables you to pick up teleseismic quakes as well as local and regional=20 ones.

Regards,

Chris Chapman

Subject: RE: 2006 SF Quake From: "Keith Payea" kpayea@........... Date: Fri, 31 Mar 2006 09:01:03 -0800 All: I'm up for it. Either day is fine. If everyone interested chimes in, we can get an idea of how many to accommodate. Keith Payea Santa Rosa, CA -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Richard Webb Sent: Friday, March 31, 2006 5:59 AM To: psn-l@.............. Subject: Re: 2006 SF Quake John, I think an informal get together on either day would be great. Dick John or Jan Lahr wrote: > I'll be attending the meeting. Maybe we should have an informal PSN > meeting one evening? > Tuesday or Wednesday would be the best for me. (April 18 or 19). > > Cheers, > John > > At 02:31 PM 3/29/2006, you wrote: >> Hi, >> >> The SSA is having the 2006 meeting in SF the week of April 17. Are >> any PSN types going to be there? >> >> Dick >> Raleigh, NC >> __________________________________________________________ >> >> Public Seismic Network Mailing List (PSN-L) >> >> To leave this list email PSN-L-REQUEST@.............. with the body >> of the message (first line only): unsubscribe >> See http://www.seismicnet.com/maillist.html for more information. > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: L15B 4.5 Geophone, detecting teleseismic earthquake From: Stephen & Kathy skmort@.......... Date: Fri, 31 Mar 2006 10:15:32 -0800 Count me in,,, I'd like to see your circuit!!!! Stephen PSN Station #55 ChrisAtUpw@....... wrote: > In a message dated 31/03/2006, system98765@............. writes: > > Hi Chris (& everyone else), > Where can one get more information about the 'Roberts Amplifier'? > Kareem > > Hi Kareem, > > Go to http://psn.quake.net/bibliography.html > > Roberts, PM "A Versatile Equilization Circuit for Increasing > Seismometer Velocity Response Below the Natural Frequency." (for 4.5Hz > geophones) BSSA, vol 79, pp 1607-1617 Oct. 1989 > > Your local library should be able to get you a photocopy. > > I made some simple circuit changes which reduced the very low > frequency noise, if anyone is interested. The modified circuit seems to > work fine. Lennartz use geophone compensators of this general type on > their professional range. You get about a factor of 10 reduction in the > minimum frequency - e.g. a 4.5Hz geophone will reproduce ~flat down to > 0.45Hz. This enables you to pick up teleseismic quakes as well as local > and regional ones. > > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L)

Subject:	Your New PSN Event File
Date:	Wed, 04 Jan 06 09:47:51 -0800
From:	event_processor@..............
To:	ian <ian@...........>