Subject: Re: A little Friday coolness From: John Lahr johnjan@........ Date: Sat, 30 Jun 2007 12:02:23 -0700 Hi Paul, There was an instrument called a seismoscope that was an inverted pendulum that scratched a smoked glass plate to record the 2-dimensional motion of the pendulum. If swung in the absence of ground motion, a record like that of a Harmonograph would be generated. See: http://www.data.scec.org/Module/sec3pg07.html and There is a picture of the outside of a seismoscope posted here: http://www.geocities.com/meredithlamb/page022.html I can't find one right now that shows the inside. Does anyone have such a picture? With out any indication of time, these records were very hard to interpret. Cheers, John At 01:06 PM 6/29/2007, you wrote: >Folks, > >With all the talk about pendulums, it reminded me of a article I saw >in a magazine once. > >The article was about a Harmonograph. > >I won't even think about the math involved that would be Chris's department. > >It seems to me like a mechanical pendulum adding machine. >Where the length, decay, friction.. all play a roll in drawing not a >seismogram, but a ...? > >Early predecessor to the Spirograph toy?? Interesting, and not too >far off topic. > >PauLC >W1VLF > >http://physics.kenyon.edu/EarlyApparatus/Oscillations_and_Waves/Harmonographs/Harmonographs.html > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismic sensors From: ChrisAtUpw@....... Date: Sat, 30 Jun 2007 19:07:05 EDT In a message dated 2007/06/29, Tangazazen@....... writes: > Hi Chris, > Each of the photo detector quadrants generate about 0.7 microamp which > are fed into virtual earth charge sensitive amplifiers. > There are numerous noise sources but as you point out the shot noise > associated with the photo current is dominant. The quadrant detector is 8mm dia, in > fact a larger detector means a larger capacitance which in turn increases the > noise. Hi Martin, What sort of seismometer are you using this on? Is it in a feedback loop? 8 mm is rather small for use with a Lehman. These tend to have appreciable drifts, but +/-1/2" is usually adequate. You can get 10mm long Si photocells quite easily. You are driving the photo output into a zero impedance maintained at zero volts. What I don't follow is where any considerations of capacity arise? And why would increased capacity increase the noise? L and C components usually have no noise associated with them. However, this seems to be a very small photocurrent. What actually limits your resolution, if it isn't the shot noise of the photocurrent? It is the 'lock-in amplifier' approach that controls the noise level. For an integration > time of a few milliseconds the effective bandwidth at 10KHz is 100 - 200 or > so Hz. Lock-in systems can pull out a signal that is substantially less than > the noise level. Certainly lock-in amplifiers make you immune to 1/f noise and the output signal is integrated. I would hope for a bandwidth considerably less than 200 Hz. I appreciate that lock-in amplifiers can allow you to dig below ambient noise levels, but what does this do to the S/N ratio? What measured resolution are you getting? > The noise level of the LED has not been noticeable. The random conversion > to photons is offset by the use of a diffuse encapsulation, a bit like an > integrating sphere. The important requirement of the LED is uniformity of the > light spot and reasonable linearity when modulated. The feedback from the sum of > the quad elements is dynamic but there is a limit to how much the amplifier > loop can correct for nonlinearity. Which LED and photocell are you using? What is the optical setup? What sort of shutter are you using? Can you not use a LED with a flat window and a metal case - no integral lens? I would expect a diffuse response to give a reduced resolution? > LED temperature dependence under constant current conditions is non linear > but -0.7% over 20C to 80C is an approximate figure for a Gallium Arsenide > Phosphide at 670nm. The feedback loop as mentioned overcomes any temperature > dependence. Interestingly LED temperature coefficients seems to get smaller at > the shorter wavelength but the quantum yield of the LED and the response of > the Silicon diode decrease, it's a question of optimisation. This is still quite a serious temperature dependence. How are you driving the LED? Is it constant on current, variable time, or constant on time, variable current? Half sine, triangle or square wave? Maybe switch to GaAs photocells? > If I had to choose between full capacitive bridge and a quad photo > detector I would choose the latter, It's a much more elegant solution. Do you have a circuit diagram, please? Regards, Chris Chapman In a me= ssage dated 2007/06/29, Tangazazen@....... writes:

Hi Chris,
      Each of the photo detector quadrants generate= about 0.7 microamp which are fed into virtual earth charge sensitive amplif= iers.
There are numerous noise sources but as you point out the shot noise associa= ted with the photo current is dominant. The quadrant detector is 8mm dia, in= fact a larger detector means a larger capacitance which in turn increases t= he noise.


Hi Martin,

       What sort of seismometer are you using=20= this on? Is it in a feedback loop? 8 mm is rather small for use with a Lehma= n. These tend to have appreciable drifts, but +/-1/2" is usually adequate. Y= ou can get 10mm long Si photocells quite easily.

       You are driving the photo output into a= zero impedance maintained at zero volts. What I don't follow is where any c= onsiderations of capacity arise? And why would increased capacity increase t= he noise? L and C components usually have no noise associated with them.

       However, this seems to be a very small=20= photocurrent. What actually limits your resolution, if it isn't the shot noi= se of the photocurrent?

It is the 'lock-in amplifier' approach that controls the noise level. For an= integration
time of a few milliseconds the= effective bandwidth at 10KHz is 100 - 200 or so Hz. Lock-in systems can pul= l out a signal that is substantially less than the noise level.

       Certainly lock-in amplifiers make you=20= immune to 1/f noise and the output signal is integrated. I would hope for a=20= bandwidth considerably less than 200 Hz. I appreciate that lock-in amplifier= s can allow you to dig below ambient noise levels, but what does this do to=20= the S/N ratio?

       What measured resolution are you gettin= g?

The noise level of the LED has=20= not been noticeable. The random conversion to photons is offset by the use o= f a diffuse encapsulation, a bit like an integrating sphere. The important r= equirement of the LED is uniformity of the light spot and reasonable lineari= ty when modulated. The feedback from the sum of the quad elements is dynamic= but there is a limit to how much the amplifier loop can correct for nonline= arity.


       Which LED and photocell are you using?=
       What is the optical setup?
       What sort of shutter are you using?
       Can you not use a LED with a flat windo= w and a metal case - no integral lens?
       I would expect a diffuse response to gi= ve a reduced resolution?

LED temperature dependence und= er constant current conditions is non linear but -0.7% over 20C to 80C is an= approximate figure for a Gallium Arsenide Phosphide at 670nm. The feedback=20= loop as mentioned overcomes any temperature dependence. Interestingly LED te= mperature coefficients seems to get smaller at the shorter wavelength but th= e quantum yield of the LED and the response of the Silicon diode decrease, i= t's a question of optimisation. 

  
       This is still quite a serious temperatu= re dependence.
       How are you driving the LED? Is it cons= tant on current, variable time, or constant on time, variable current? Half=20= sine, triangle or square wave?
       Maybe switch to GaAs photocells?=

If I had to choose between ful= l capacitive bridge and a quad photo detector I would choose the latter, It'= s a much more elegant solution.


       Do you have a circuit diagram, please?<= BR>
       Regards,

       Chris Chapman Subject: Re: Seismic sensors From: Tangazazen@....... Date: Sun, 1 Jul 2007 06:19:04 EDT Hi Chris, The seismometer is not a Lehman but a single pendulum with a natural period of 1 second. It is supported by two pairs of leaf suspensions arranged in a gimble form and give the pendulum two degrees of freedom but no rotation about it's axis. The LED and projection optics are mounted on the lower end and projects a 4mm spot of light modulated at 10KHz onto the quadrant photo cell. The quadrant detector produces the X & Y components of motion which in turn, via phase-sensitive detectors and appropriate feedback to orthogonal force transducers, hold the pendulum in a fixed position. A two axis broadband in fact but with a period of 60 seconds. The two axis output signals are of course the restraining force in volts/meter/second. Unlike the vertical broadband, temperature correction is unnecessary and tilt errors are compensated by giving the integrator a large dynamic range. The capacitance does not directly generate noise but modifies the source impedance which in turn change the ratio of the noise voltage to noise current contributions to the total noise. The photo current of 0.7 micro amps is large compared with the FET gate leakage current and is the dominate noise source. Narrower bandwidths of lock-in systems will improve the S/N ratio but may compromise the transient response, it's a question of optimisation. The important characteristics of the LED are uniformity of the light spot and linearity. The LED control feedback is dynamic i.e. both amplitude and wave form are controlled, but there is a limit to how much the loop can correct non-linearity before the onset of instability. The theoretical analysis of Force Balance Feedback is covered in Thomas Forbriger and Erhard Wielandt papers, the former is in German but the more practical aspects are well documented by Sean-Thomas Morrissey and Allen Coleman. I should perhaps point out that large quadrant silicon photo detectors are a little expensive to say the least and I would not have use this approach if I had not been given a handful. Regards Martin
Hi Chris,
 
     The seismometer is not a Lehman but a single=20 pendulum with a natural period of 1 second. It is supported by two pairs of=20= leaf=20 suspensions arranged in a gimble form and give the pendulum two degrees of=20 freedom but no rotation about it's axis. The LED and projection optics=20= are=20 mounted on the lower end and projects a 4mm spot of light modulated at 10KHz= =20 onto the quadrant photo cell. The quadrant detector produces the X & Y=20 components of motion which in turn, via phase-sensitive detectors and=20 appropriate feedback to orthogonal force transducers, hold the pendulum in a= =20 fixed position. A two axis broadband in fact but with a period of 60=20 seconds. The two axis output signals are of course the restraining forc= e in=20 volts/meter/second. Unlike the vertical broadband, temperature correction is= =20 unnecessary and tilt errors are compensated by giving the integrator a large= =20 dynamic range. 
 
The capacitance does not directly generate noise but modifies the=20 source impedance which in turn change the ratio of the noise voltage to nois= e=20 current contributions to the total noise. The photo current of 0.7 micr= o=20 amps is large compared with the FET gate leakage current and is the dominate= =20 noise source.
 
Narrower bandwidths of lock-in systems will improve the S/N ratio but m= ay=20 compromise the transient response, it's a question of optimisation.
 
The important characteristics of the LED are uniformity of the light sp= ot=20 and linearity. The LED control feedback is dynamic i.e. both amplitude and w= ave=20 form are controlled, but there is a limit to how much the loop can=20 correct non-linearity before the onset of instability.
 
The theoretical analysis of Force Balance Feedback is covered in Thomas= =20 Forbriger and Erhard Wielandt papers, the former is in German but the more=20 practical aspects are well documented by Sean-Thomas Morrissey and Allen=20 Coleman.
 
 I should perhaps point out that large quadrant silicon photo=20 detectors are a little expensive to say the least and I would not have use t= his=20 approach if I had not been given a handful.
 
 
 
 Regards Martin
 Subject: Earthquake at 110km depth ?! From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Sun, 01 Jul 2007 13:06:57 +0000 Hi all The SIL network of the Icelandic met office has detected something intresting, the automatic system shows a earthquake at 110km depth, where the crust is only ~30 km thick. This might be a error, but my station shows a event at that same time. If this earthquake gets confirmed at depth of more then 30km there must be something intresting be under the crust in my area. I did check for gloabl earthquake and I didn't see any event big enugh to create a false local earthquake, but that requires a mag 8.0+ less then 7700 km away from Iceland to do that. Any suggestion on what this is are welcomed. Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthquake at 110km depth ?! From: Mark Robinson mark.robinson@............... Date: Mon, 02 Jul 2007 02:09:21 +1200 Jón Frímann wrote: > Hi all > > The SIL network of the Icelandic met office has detected something > intresting, the automatic system shows a earthquake at 110km depth, > where the crust is only ~30 km thick. This might be a error, but my > station shows a event at that same time. If this earthquake gets > confirmed at depth of more then 30km there must be something intresting > be under the crust in my area. > > I did check for gloabl earthquake and I didn't see any event big enugh > to create a false local earthquake, but that requires a mag 8.0+ less > then 7700 km away from Iceland to do that. > > Any suggestion on what this is are welcomed. Hi Jón, You might be interested to look at this image: http://www.geonet.org.nz/images/earthquake/quakes/2757147gc.png It's a scattergram of earthquake locations mapped onto the earth's surface and a plot showing the depth of the quakes along a line perpendicular to the major fault. I'm sure you'll be able to find similar plots for Iceland. -- cheers Mark __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthquake at 110km depth ?! From: John Lahr johnjan@........ Date: Sun, 01 Jul 2007 08:04:25 -0700 J=F3n, You can explore in map view and cross section the=20 seismicity of any area with the free program=20 SeismicEruption. This is on Alan Jones' web site: http://www.geol.binghamton.edu/faculty/jones/ To visualize the paths of teleseismic arrivals, Alan's program SeismicWaves= is excellent (from the same site). Cheers, John At 07:09 AM 7/1/2007, you wrote: >J=F3n Fr=EDmann wrote: >>Hi all >> >>intresting, the automatic system shows a earthquake at 110km depth, > >Hi J=F3n, > >You might be interested to look at this image: > >I'm sure you'll be able to find similar plots for Iceland. >-- >cheers >Mark > >____________ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthquake at 110km depth ?! From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Sun, 01 Jul 2007 15:31:43 +0000 Hi all The only telesesmic earthquake that is close to this event is a mb5.5 earthquake in Japan at 04:12 UTC. http://www.emsc-csem.org/index.php?page=3Dcurrent&sub=3Ddetail&id=3D48436 But I do not think that this event is big enugh to create a viewable wave on the SIL network, but that is based on 1Hz stations and my 4.5Hz geophone, I have have had bigger events closer then this and not seen them. This is a mistery to me. Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthquake at 110km depth ?! From: Tangazazen@....... Date: Sun, 1 Jul 2007 12:14:35 EDT Hi Jon, It might well be the M 5.5 earthquake from Japan at 04:12 UTC. While my recorder was not active the seismometer alarm did wake me unfortunately, just after that time. I have in the past picked up the M 5.4 from Luzon on 6-5-07 and a whole series from Ryukyo Islands on 20-4-07. The later consisted of 7 events ranging from 5.1 to 6.1 between 00:26:45 to 05:23:11 UTC. I wish some of these teleseismic events would occur during more civilised hours! Regards Martin
Hi Jon,
 
   It might well be the M 5.5 earthquake from Japan at 04:12=20= UTC.=20 While my recorder was not active the seismometer alarm did wake me= =20 unfortunately, just after that time. I have in the past picked up the&n= bsp;=20 M 5.4 from Luzon on 6-5-07 and a whole series from Ryukyo Islands on 20-4-07= ..=20 The later consisted of 7 events ranging from 5.1 to 6.1 between 00:26:45 to=20 05:23:11 UTC.  I wish some of these teleseismic events would occur= =20 during more civilised hours!
 
 
Regards Martin
 Subject: Re: Seismic sensors From: ChrisAtUpw@....... Date: Sun, 1 Jul 2007 13:47:39 EDT In a message dated 2007/07/01 11:19:30 GMT Daylight Time, Tangazazen@....... writes: > Subj:Re: Seismic sensors > Date:2007/07/01 11:19:30 GMT Daylight Time > From:Tangazazen@....... > Reply-to:psn-l@.............. > To:psn-l@.............. > Sent from the Internet > > > > Hi Chris, > > The seismometer is not a Lehman but a single pendulum with a natural > period of 1 second. It is supported by two pairs of leaf suspensions arranged > in a gimble form and give the pendulum two degrees of freedom but no rotation > about it's axis. The LED and projection optics are mounted on the lower end > and projects a 4mm spot of light modulated at 10KHz onto the quadrant photo > cell. The quadrant detector produces the X & Y components of motion which in > turn, via phase-sensitive detectors and appropriate feedback to orthogonal > force transducers, hold the pendulum in a fixed position. A two axis broadband in > fact but with a period of 60 seconds. The two axis output signals are of > course the restraining force in volts/meter/second. Unlike the vertical > broadband, temperature correction is unnecessary and tilt errors are compensated by > giving the integrator a large dynamic range. > > The capacitance does not directly generate noise but modifies the source > impedance which in turn change the ratio of the noise voltage to noise current > contributions to the total noise. The photo current of 0.7 micro amps is large > compared with the FET gate leakage current and is the dominate noise source. > > Narrower bandwidths of lock-in systems will improve the S/N ratio but may > compromise the transient response, it's a question of optimisation. > > The important characteristics of the LED are uniformity of the light spot > and linearity. The LED control feedback is dynamic i.e. both amplitude and wave > form are controlled, but there is a limit to how much the loop can correct > non-linearity before the onset of instability. > > The theoretical analysis of Force Balance Feedback is covered in Thomas > Forbriger and Erhard Wielandt papers, the former is in German but the more > practical aspects are well documented by Sean-Thomas Morrissey and Allen Coleman. > > I should perhaps point out that large quadrant silicon photo detectors are > a little expensive to say the least and I would not have use this approach if > I had not been given a handful. > > > > Regards Martin > In a me= ssage dated 2007/07/01 11:19:30 GMT Daylight Time, Tangazazen@....... writes= :


Subj:Re: Seismic sensors
Date:2007/07/01 11:19:30 GMT Daylight Time
From:Tangazazen@.......
Reply-to:psn-l@.............. To:psn-l@..............
Sent from the Internet



Hi Chris,

     The seismometer is not a Lehman but a single pendul= um with a natural period of 1 second. It is supported by two pairs of leaf s= uspensions arranged in a gimble form and give the pendulum two degrees of fr= eedom but no rotation about it's axis. The LED and projection optics are mou= nted on the lower end and projects a 4mm spot of light modulated at 10KHz on= to the quadrant photo cell. The quadrant detector produces the X & Y com= ponents of motion which in turn, via phase-sensitive detectors and appropria= te feedback to orthogonal force transducers, hold the pendulum in a fixed po= sition. A two axis broadband in fact but with a period of 60 seconds. The tw= o axis output signals are of course the restraining force in volts/meter/sec= ond. Unlike the vertical broadband, temperature correction is unnecessary an= d tilt errors are compensated by giving the integrator a large dynamic range= ..

The capacitance does not directly generate noise but modifies the source imp= edance which in turn change the ratio of the noise voltage to noise current=20= contributions to the total noise. The photo current of 0.7 micro amps is lar= ge compared with the FET gate leakage current and is the dominate noise sour= ce.

Narrower bandwidths of lock-in systems will improve the S/N ratio but may co= mpromise the transient response, it's a question of optimisation.

The important characteristics of the LED are uniformity of the light spot an= d linearity. The LED control feedback is dynamic i.e. both amplitude and wav= e form are controlled, but there is a limit to how much the loop can correct= non-linearity before the onset of instability.

The theoretical analysis of Force Balance Feedback is covered in Thomas Forb= riger and Erhard Wielandt papers, the former is in German but the more pract= ical aspects are well documented by Sean-Thomas Morrissey and Allen Coleman.=

I should perhaps point out that large quadrant silicon photo detectors are=20= a little expensive to say the least and I would not have use this approach i= f I had not been given a handful.



Regards Martin


 Subject: Re: Seismic sensors From: ChrisAtUpw@....... Date: Sun, 1 Jul 2007 13:53:19 EDT In a message dated 2007/07/01 11:19:30 GMT Daylight Time, Tangazazen@....... writes: > The important characteristics of the LED are uniformity of the light spot > and linearity. The LED control feedback is dynamic i.e. both amplitude and > wave form are controlled, but there is a limit to how much the loop can correct > non-linearity before the onset of instability. > > I should perhaps point out that large quadrant silicon photo detectors are > a little expensive to say the least. Hi Martin, Do you use a round or a square spot and do you use a mask to define it accurately? What are the type numbers of your driver LED and the photodetector, please? Regards, Chris Chapman In a me= ssage dated 2007/07/01 11:19:30 GMT Daylight Time, Tangazazen@....... writes= :


The important characteristics o= f the LED are uniformity of the light spot and linearity. The LED control fe= edback is dynamic i.e. both amplitude and wave form are controlled, but ther= e is a limit to how much the loop can correct non-linearity before the onset= of instability.

I should perhaps point out that large quadrant silicon photo detectors are=20= a little expensive to say the least.


Hi Martin,

       Do you use a round or a square spot and= do you use a mask to define it accurately?

       What are the type numbers of your drive= r LED and the photodetector, please?

       Regards,
      
       Chris Chapman Subject: 6 month to go From: tchannel1@............ Date: Mon, 2 Jul 2007 21:48:32 -0600 Hi All, Where are all the big ones? Or should I ask, Major ones? = Years 2000-2006 averaged 12, Earthquakes 7.0-7.9M, per year. With six months gone and six months to go, this site shows 2 thus far, = this year. At this rate we would only see two more, for a total of = four, vs. twelve. I would think, from this, we are either going to = have a very slow year for Major earthquakes, or its going to be busy the = next six month. We would need 1.666 Majors events each month, to the = end of the year just to maintain that six year average. (Was it )? John, please let us know it you unplug your machine again. Ted http://www.infoplease.com/ipa/A0197840.html
Hi All,  Where are all the big=20 ones?   Or should  I ask, Major ones?  Years = 2000-2006=20 averaged 12, Earthquakes  7.0-7.9M, per year.
With six months gone and six months to = go, this=20 site shows 2 thus far, this year.  At this rate we would only see = two more,=20 for a total of four, vs. twelve.     I would think, = from=20 this, we are either going to have a very slow year for Major = earthquakes, or its=20 going to be busy the next six month.  We would need 1.666 Majors = events=20 each month, to the end of the year just to maintain that six year=20 average.
 
(Was it )? John, please let us know it = you unplug=20 your machine again.
Ted
 
 
 
 
http://www.infopleas= e.com/ipa/A0197840.html
Subject: Re: Period From: "Geoffrey" gmvoeth@........... Date: Tue, 3 Jul 2007 02:17:31 -0700 Hello tchannel1, I think it might be interesting to sum all three axis possibly by some kind of vector math to obtain a single signal. I have never done this before but I know for a fact the main signal most probably is not in any of the three planes but some vector of all three together. Regards; geoff ----- Original Message ----- From: To: Sent: Saturday, June 30, 2007 06:07 Subject: Period Hi All, I just did a side by side comparison of an Earthquake recorded by a Vertical with a 2? second period and a Horz Pendulum with a 10? second period. The different on this 6.7M at 10000km was very pronounced, showing all the advantages of the Horz. However, using the Vertical, I record many more Earthquake, and smaller ones. If the event is large, both sensors are impressive (to me). In planning my next sensor, I need to pick a target period. I already see the advantage of each. What period might be the best target? Or is it just better to pick one end of the spectrum and not the center? Thanks, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Period From: "Geoffrey" gmvoeth@........... Date: Tue, 3 Jul 2007 03:44:57 -0700 Hello tchannel1; This is a response to your post and intended for everyone at PSN. A period range of 0.2 Hz to 2Hz is by far the best range for seeing P and S of most EQ signals If one lives in a noisy area with lots of vehicular traffic this is the best range to use. In this range you should be able to crank up the gain until you see both low and high frq noise about +/- two samples maybe four then you should be able to see a 4.0 regional quake at 6 degrees of distance as the guideline for a MDL (Minimum discernable level). The smaller the bandwidth the less the noise. If you are in a quiet area by all means open up the bandwidth to see the close quakes better. If you have like a 24 bit A/D converter you can make the gain adjustable simply be looking at 8 or 12 or 16 bits and scaling everything else then you can digitally set the gain from the keyboard. If you program a modulo recorder of 12 minutes or so there are almost no earthquakes of any size that you will miss with a computer oriented recorder and a seismic alarm that works something like a venus fly trap trigger hairs. Do you know if anyone has ever used a laser pointer in a seismic sensor ? Possibly using surfaced mirrors to provide mechanical amplification like a lever arm ? If you do not build your own electronics and program your own software then most probably forget these finer details. Like Always, I am no expert but i do have several broken years of practical experience. To me an Amateur can be a layman who simply watches the signals and cares nothing more about the science since an amateur receives No pay for his hobby. Laymen Professional Expert are different ideas. I think you can find all three in any amateur group. I am an Amateur layman with some formal technical education and experience but no degree\certificates that means anything. The range I tell you here is from personal experience over the past 13 years. I have found the 500LB geophone used all over the world by the USGS gives the best signal right down to 20 seconds even tho it is a 1sec free period device. It does not have the severe natural damping of the smaller geophones but does have a very powerful magnet. My thought is this; The sensor should be in a vacuum and have a very powerful magnet and in a faraday shield otherwise the sensor will typically be marginal at best. Everything needs to be shielded and bonded between the Computer including the sensor. AntiAlising filtration by whatever means prior to conversion/recording by the A/D converter. Do not use the sensor coil for damping because that reduces sensitivity but instead use a seperate magnet/Copper Plate arrangement. The preamplifier to be a differential type with both +/- of the opamp equalized for DC. Put as little load on the sensor as possible. It used to be easy to get copper in Arizona but not any more unless you pay lots of cash, copper has become outrageously expensive along with everything else. It seems to me they (My Country/USA) do not want people playing around with Science and Technology unless they are rich or Formally educated. I think they (My USA) are overly Religious and overly paranoid. The majority of people here are not well enough educated (including myself). It is humbling to note that after study of life that intelligence/education are not necessary for survival. Winquake is the best public seismic program I have seen for the layman. I will convert my data to text to use in winquake and find the data easier to analyze. But to be most precise and accurate I will read using my own program on a sample by sample bases. Winquake gives a sort of standard for PSN and lets people share their data. But I have found that if you are converting your own data into PSN form you must start the first sample relating to an exact start of minute or the times will not be right. In Winquake You must test your sample rate and make sure its right. Start all your data for winquake at HH:MM:00.0 the seconds always being zero for your very first sample. You need cal markes from WWV/CHU or something like that to see the top of second zero in each minute. Say Minute 59-60 second mark goes high at sample #1025 use sample #1024 as the very first sample and stop the samples at the N= The next cal mark high - one sample at the end. Winquake should agree that the times are all right so long as you got the sample rate right. Winquake does not give me good times if I do not follow this idea. I can not just start out in the middle of a minute and end just anywhere. Without Cal marks of some standard type the times for the layman are uncertain. Winquake needs a FFT waterfall display to see a movie like of shifting frequencies over time. Possibly in 1024 sample chunks advancing one sample for the next 1024. Nothing fancy, Black and white and shades of gray, totally suitable. Regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: 6 month to go From: "Michael Kimzey" mckimzey@........... Date: Tue, 03 Jul 2007 07:40:59 -0400 >With six months gone and six months to go, this site shows 2 thus far, this >year. At this rate we would only see two more, for a total of four, vs. >twelve. I would think, from this, we are either going to have a very >slow year for Major earthquakes, or its going to be busy the next six >month. We would need 1.666 Majors events each month, to the end of the >year just to maintain that six year average. > >(Was it )? John, please let us know it you unplug your machine again. >Ted > It was me...and all sensors are on-line again...and just to further confound everyone, I collecting parts for a copy of Sean's Vertical. When it's complete, I expect the cessation of all seismic activity across the world!! - Mike __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Period From: ChrisAtUpw@....... Date: Tue, 3 Jul 2007 09:30:11 EDT In a message dated 2007/07/03, gmvoeth@........... writes: > Do you know if anyone has ever used a laser pointer > in a seismic sensor ? Possibly using surfaced mirrors > to provide mechanical amplification like a lever arm ? Hi Geoff, Laser pointers are very noisy and drift in intensity with temperature. You could maybe use a multiple reflection optical lever system with surface silvered mirrors, but getting satisfactory results may be difficult. The red light is too long a wavelength to use interference fringe counting at all easily. You have steps of ~300 nano metres between each fringe. Sensing to a fraction of a wavelength is possible using Moire fringes, but costly. Using large area differential Si or GaAs photocells and a stabilised voltage tungsten bulb work reasonably well. You can also use IR LEDs, but you need to stabilise the output - the photo output drifts quite strongly with temperature. IR and Superbright LEDs may be reasonably quiet, but ordinary LEDs can be quite noisy. The % noise decreases with increasing total photo current. The signal is proportional to the number of photons N in any sample, but the noise is proportional to Sqrt N. The size of the detector needs to be several thousand wavelengths minimum. You can also use IR LEDs in pulsed mode as the signal generator in a phase lock loop differential photo detector system, but the photo output needs to be stabilised. Photo detectors are well described at http://sales.hamamatsu.com/assets/applications/SSD/photodiode_technical_information.pdf Regards, Chris Chapman In a me= ssage dated 2007/07/03, gmvoeth@........... writes:

Do you know if anyone has ever=20= used a laser pointer
in a seismic sensor ? Possibly using surfaced mirrors
to provide mechanical amplification like a lever arm ?


Hi Geoff,

       Laser pointers are very noisy and drift= in intensity with temperature. You could maybe use a multiple reflection op= tical lever system with surface silvered mirrors, but getting satisfactory r= esults may be difficult.
       The red light is too long a wavelength=20= to use interference fringe counting at all easily. You have steps of ~300 na= no metres between each fringe. Sensing to a fraction of a wavelength is poss= ible using Moire fringes, but costly.

       Using large area differential Si or GaA= s photocells and a stabilised voltage tungsten bulb work reasonably well. Yo= u can also use IR LEDs, but you need to stabilise the output - the photo out= put drifts quite strongly with temperature. IR and Superbright LEDs may be r= easonably quiet, but ordinary LEDs can be quite noisy.
       The % noise decreases with increasing t= otal photo current. The signal is proportional to the number of photons N in= any sample, but the noise is proportional to Sqrt N. The size of the detect= or needs to be several thousand wavelengths minimum.

       You can also use IR LEDs in pulsed mode= as the signal generator in a phase lock loop differential photo detector sy= stem, but the photo output needs to be stabilised.

       Photo detectors are well described at h= ttp://sales.hamamatsu.com/assets/applications/SSD/photodiode_technical_infor= mation.pdf
      
       Regards,

       Chris Chapman

 Subject: Yes we felt it! 4.3M Central California From: tchannel1@............ Date: Tue, 3 Jul 2007 08:02:20 -0600 Hi All, Linda's Brother in Morgan Hill Ca. 16.5 miles North of the = 070702.195853.tcidzs.psn writes: =20 "Hi Linda and Ted, Yes, we did feel the earthquake at 12:58 this afternoon. I always look = at the clock when we have an earthquake so I knew your time was right = on. The dishes in my kitchen cupboards even rattled." We=20
Hi All,  Linda's Brother in Morgan = Hill=20 Ca.  16.5 miles North of the 070702.195853.tcidzs.psn writes:  =

"Hi Linda and = Ted,

Yes, we did = feel the=20 earthquake at 12:58 this afternoon. I always look at the clock when we = have an=20 earthquake so I knew your time was right on. The dishes in my kitchen = cupboards=20 even rattled."

We=20

Subject: RE: Period From: "Bob Hancock" carpediem1@......... Date: Tue, 3 Jul 2007 07:03:52 -0700 Hi Geoff - If you did sum all the channels, how would you compensate for the fact that the P & S body waves do not always have the same initial direction (compression or dilation,) of travel on all channels. In addition, how would you compensate for Love waves which only appear on the transverse channel, and Rayleigh wave only appears only on the vertical and radial channels? Finally, the fault dynamics (focal mechanism) adds it own twist to the amplitudes of waves and how visible they will be depending upon the event to station and station to event azimuths. It would take a very complex algorithm to accomplish this and while I am certain it could be done, I am not sure just what would be accomplished. Bob -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Geoffrey Sent: Tuesday, July 03, 2007 02:18 To: psn-l@.............. Subject: Re: Period Hello tchannel1, I think it might be interesting to sum all three axis possibly by some kind of vector math to obtain a single signal. I have never done this before but I know for a fact the main signal most probably is not in any of the three planes but some vector of all three together. Regards; geoff ----- Original Message ----- From: To: Sent: Saturday, June 30, 2007 06:07 Subject: Period Hi All, I just did a side by side comparison of an Earthquake recorded by a Vertical with a 2? second period and a Horz Pendulum with a 10? second period. The different on this 6.7M at 10000km was very pronounced, showing all the advantages of the Horz. However, using the Vertical, I record many more Earthquake, and smaller ones. If the event is large, both sensors are impressive (to me). In planning my next sensor, I need to pick a target period. I already see the advantage of each. What period might be the best target? Or is it just better to pick one end of the spectrum and not the center? Thanks, Ted __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 6 month to go From: tchannel1@............ Date: Tue, 3 Jul 2007 08:11:48 -0600 Mike, Thanks, and we will be watching. Ted ----- Original Message ----- From: "Michael Kimzey" To: Sent: Tuesday, July 03, 2007 5:40 AM Subject: RE: 6 month to go > > >>With six months gone and six months to go, this site shows 2 thus far, >>this year. At this rate we would only see two more, for a total of four, >>vs. twelve. I would think, from this, we are either going to have a >>very slow year for Major earthquakes, or its going to be busy the next six >>month. We would need 1.666 Majors events each month, to the end of the >>year just to maintain that six year average. >> >>(Was it )? John, please let us know it you unplug your machine again. >>Ted >> > > It was me...and all sensors are on-line again...and just to further > confound everyone, I collecting parts for a copy of Sean's Vertical. When > it's complete, I expect the cessation of all seismic activity across the > world!! > > - Mike > > > __________________________________________________________ > > 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: Period From: tchannel1@............ Date: Tue, 3 Jul 2007 08:13:23 -0600 Hi Geoff, >Do you know if anyone has ever used a laser pointer in a seismic sensor ? Possibly using surfaced mirrors to provide mechanical amplification like a lever arm ? No I do not. Thanks for all this good information. Ted ----- Original Message ----- From: "Geoffrey" To: Sent: Tuesday, July 03, 2007 4:44 AM Subject: Re: Period > Hello tchannel1; > > This is a response to your post and intended > for everyone at PSN. > > A period range of 0.2 Hz to 2Hz is by far the best > range for seeing P and S of most EQ signals > If one lives in a noisy area with lots of vehicular > traffic this is the best range to use. In this range you > should be able to crank up the gain until you see > both low and high frq noise about +/- two samples > maybe four then you should be able to see a 4.0 > regional quake at 6 degrees of distance as the > guideline for a MDL (Minimum discernable level). > The smaller the bandwidth the less the noise. > If you are in a quiet area by all means open up the bandwidth > to see the close quakes better. > If you have like a 24 bit A/D converter you can make the gain > adjustable simply be looking at 8 or 12 or 16 bits and scaling > everything else then you can digitally set the gain from > the keyboard. > > If you program a modulo recorder of 12 minutes or so > there are almost no earthquakes of any size > that you will miss with a computer oriented recorder > and a seismic alarm that works something like a venus fly trap > trigger hairs. > > Do you know if anyone has ever used a laser pointer > in a seismic sensor ? Possibly using surfaced mirrors > to provide mechanical amplification like a lever arm ? > > If you do not build your own electronics and program your own > software then most probably forget these finer details. > Like Always, I am no expert but i do have several broken > years of practical experience. > > To me an Amateur can be a layman who simply watches the signals > and cares nothing more about the science since an amateur receives > No pay for his hobby. Laymen Professional Expert are different ideas. > I think you can find all three in any amateur group. I am an Amateur > layman > with some formal technical education and experience but no > degree\certificates > that means anything. > The range I tell you here is from personal experience over the past 13 > years. > I have found the 500LB geophone used all over the world by the USGS gives > the > best signal right down to 20 seconds even tho it is a 1sec free period > device. > It does not have the severe natural damping of the smaller geophones > but does have a very powerful magnet. > > My thought is this; > The sensor should be in a vacuum and have a very powerful magnet > and in a faraday shield otherwise the sensor will typically be marginal at > best. > Everything needs to be shielded and bonded between the Computer including > the sensor. > AntiAlising filtration by whatever means prior to conversion/recording by > the A/D converter. > Do not use the sensor coil for damping because that reduces sensitivity > but instead > use a seperate magnet/Copper Plate arrangement. The preamplifier to be a > differential type with both +/- of the opamp equalized for DC. > Put as little load on the sensor as possible. > It used to be easy to get copper in Arizona but not any more > unless you pay lots of cash, copper has become outrageously expensive > along with everything else. > It seems to me they (My Country/USA) do not want people playing > around with Science and Technology unless they are rich or > Formally educated. I think they (My USA) are overly Religious and overly > paranoid. > The majority of people here are not well enough educated (including > myself). > It is humbling to note that after study of life that > intelligence/education are not necessary for survival. > > Winquake is the best public seismic program I have seen for the layman. > I will convert my data to text to use in winquake and find the data > easier to analyze. But to be most precise and accurate I will read > using my own program on a sample by sample bases. > Winquake gives a sort of standard for PSN and lets people > share their data. But I have found that if you are converting > your own data into PSN form you must start the first sample > relating to an exact start of minute or the times will not be right. > In Winquake You must test your sample rate and make sure its right. > Start all your data for winquake at HH:MM:00.0 the seconds always > being zero for your very first sample. You need cal markes from > WWV/CHU or something like that to see the top of second zero > in each minute. > Say Minute 59-60 second mark goes high at sample #1025 > use sample #1024 as the very first sample and stop the samples > at the N= The next cal mark high - one sample at the end. Winquake > should agree that the times are all right so long as you got the > sample rate right. > Winquake does not give me good times if I do not follow this idea. > I can not just start out in the middle of a minute and end just anywhere. > Without Cal marks of some standard type the times for the layman are > uncertain. > > Winquake needs a FFT waterfall display to see a movie like of > shifting frequencies over time. > Possibly in 1024 sample chunks advancing one sample for the next 1024. > Nothing fancy, Black and white and shades of gray, totally suitable. > > Regards; > geoff > __________________________________________________________ > > 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: 6 month to go From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Tue, 03 Jul 2007 17:11:26 +0000 Hi all I have to repair my computer tomorrow. I am expecting stuff to happen. :-/ I have to replace the video card in my computer, the one I currently have is dieing and giving bad colors and dark screen. That is also the reason why I haven't send in new earthquakes for the past days. Besides that I have been away for two weeks now in vacation. Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Period From: Bobhelenmcclure@....... Date: Tue, 3 Jul 2007 21:40:38 EDT On 3 Jul 2007 03:44:57 gmvoeth@....... wrote: Winquake needs a FFT waterfall display to see a movie like of shifting frequencies over time. Possibly in 1024 sample chunks advancing one sample for the next 1024. Nothing fancy, Black and white and shades of gray, totally suitable. Hi Geoff, WinQuake does not have a waterfall display, but it does have a useful procedure for viewing a scanning spectrogram. Here is how: (1) Set "X Scale" to the time interval window you want to use for an FFT. You will get a slider button on the bottom of the screen which will allow you to view any portion of the event record. (2) From the menu bar, select "Calculate", "FFT...", "View Only". An FFT plot will appear. (3) From the menu bar, select "Window", "Arrange". You can then simultaneously view the windowed event data and the FFT for the window. (4) Use the slider button to scan through the file. As the event data slides through the window, the FFT display will update almost continuously to display the spectrum for the data displayed in the window. (Unfortunately, the scale for the FFT may change as well.) Bob PSN Station REM Locust Valley, NY ************************************** See what's free at http://www.aol.com.
On 3 Jul 2007 03:44:57 gmvoeth@....... wrote:
Winquake needs a FFT=20 waterfall display to see a movie like of shifting frequencies over=20 time.
Possibly in 1024 sample chunks advancing one sample for the next=20 1024.
Nothing fancy, Black and white and shades of gray,  totally=20 suitable.
 
Hi Geoff,
 
  WinQuake does not have a waterfall display, but it does have a=20 useful procedure for viewing a scanning spectrogram. Here is how:
 
(1) Set "X Scale" to the time interval window you want to use for an FF= T.=20 You will get a slider button on the bottom of the screen which will allow yo= u to=20 view any portion of the event record.
 
(2) From the menu bar, select "Calculate", "FFT...", "View Only". An FF= T=20 plot will appear.
 
(3) From the menu bar, select "Window", "Arrange". You can then=20 simultaneously view the windowed event data and the FFT for the window.
 
(4) Use the slider button to scan through the file. As the event data=20 slides through the window, the FFT display will update almost continuously t= o=20 display the spectrum for the data displayed in the window. (Unfortunately, t= he=20 scale for the FFT may change as well.)
 
Bob
PSN Station REM
Locust Valley, NY



See what's free at AOL.com.
Subject: RE: Period From: "Paul Cianciolo" Paulc@........ Date: Thu, 5 Jul 2007 09:50:01 -0400 Bob, Geoff This was quite helpful as it was a question I had been wondering about as well. PauLC W1VLF -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Bobhelenmcclure@....... Sent: Tuesday, July 03, 2007 9:41 PM To: psn-l@.............. Cc: gmvoeth@........... Subject: Re: Period On 3 Jul 2007 03:44:57 gmvoeth@....... wrote: Winquake needs a FFT waterfall display to see a movie like of shifting frequencies over time. Possibly in 1024 sample chunks advancing one sample for the next 1024. Nothing fancy, Black and white and shades of gray, totally suitable. Hi Geoff, WinQuake does not have a waterfall display, but it does have a useful procedure for viewing a scanning spectrogram. Here is how: (1) Set "X Scale" to the time interval window you want to use for an FFT. You will get a slider button on the bottom of the screen which will allow you to view any portion of the event record. (2) From the menu bar, select "Calculate", "FFT...", "View Only". An FFT plot will appear. (3) From the menu bar, select "Window", "Arrange". You can then simultaneously view the windowed event data and the FFT for the window. (4) Use the slider button to scan through the file. As the event data slides through the window, the FFT display will update almost continuously to display the spectrum for the data displayed in the window. (Unfortunately, the scale for the FFT may change as well.) Bob PSN Station REM Locust Valley, NY ---------------------------------------------------------------------------- -- See what's free at AOL.com.
Bob, Geoff
 
This was quite helpful as it was a = question=20 I had been wondering about as well.
 
 
 
PauLC
W1VLF
 
 
 
 -----Original=20 Message-----
From: psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of=20 Bobhelenmcclure@.......
Sent: Tuesday, July 03, 2007 9:41=20 PM
To: psn-l@..............
Cc:=20 gmvoeth@...........
Subject: Re: Period

On 3 Jul 2007 03:44:57 gmvoeth@....... wrote:
Winquake needs a = FFT=20 waterfall display to see a movie like of shifting frequencies over=20 time.
Possibly in 1024 sample chunks advancing one sample for the = next=20 1024.
Nothing fancy, Black and white and shades of gray,  = totally=20 suitable.
 
Hi Geoff,
 
  WinQuake does not have a waterfall display, but it does = have a=20 useful procedure for viewing a scanning spectrogram. Here is = how:
 
(1) Set "X Scale" to the time interval window you want to use for = an FFT.=20 You will get a slider button on the bottom of the screen which will = allow you=20 to view any portion of the event record.
 
(2) From the menu bar, select "Calculate", "FFT...", "View Only". = An FFT=20 plot will appear.
 
(3) From the menu bar, select "Window", "Arrange". You can then=20 simultaneously view the windowed event data and the FFT for the = window.
 
(4) Use the slider button to scan through the file. As the event = data=20 slides through the window, the FFT display will update almost = continuously to=20 display the spectrum for the data displayed in the window. = (Unfortunately, the=20 scale for the FFT may change as well.)
 
Bob
PSN Station REM
Locust Valley, NY



See what's free at AOL.com.=20
Subject: Earthquake in Canada! From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Fri, 06 Jul 2007 02:07:26 +0000 Hi all A rare event just happend, a earthquake in Canada, http://www.emsc-csem.org/index.php?page=3Dcurrent&sub=3Ddetail&id=3D48916 Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Earthquake in Canada! From: "Michael Kimzey" mckimzey@........... Date: Thu, 05 Jul 2007 22:17:10 -0400 There was just one in Mexico, also. The one in Canada may also be in the signal I recorded. This will be a first for me, but I will get to work with 2 P and S' on the same signal. Nice. - Mike __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Earthquake in Canada! From: =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= jonfr@......... Date: Fri, 06 Jul 2007 04:04:49 +0000 Hi all I am looking at the raw date from emsc, is it possible that the earthquake in Canada is actually a false one ? USGS does not list it as current, the raw data from emsc can be seen here, http://www.emsc-csem.org/index.php?page=3Dcurrent&sub=3Dmsg Regards. --=20 J=F3n Fr=EDmann http://www.jonfr.com http://www.simnet.is/jonfr500/earthquake/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Earthquake in Canada! From: "Michael Kimzey" mckimzey@........... Date: Fri, 06 Jul 2007 06:42:55 -0400 >I am looking at the raw date from emsc, is it possible that the >earthquake in Canada is actually a false one ? USGS does not list it as >current, the raw data from emsc can be seen here, >http://www.emsc-csem.org/index.php?page=current&sub=msg I suspect that it might be a false alarm. The main screen doesn't even list it. The linked page does have that disclaimer that it's raw data only... - Mike __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Did I feel it??? From: tchannel1@............ Date: Fri, 6 Jul 2007 10:51:57 -0600 This is a new story: My wife Linda (IMMG Museum) came upstairs from = our basement last night and said she was sure she felt the earth move! = I was standing in front of the fridge, looking at the last two cupcakes, = "Should I eat the two cupcakes, or have some nice carrots? Let's see, = if I choose the cupcakes, I could eat just one, at 250 calories=3D30 = mins on the treadmill, or I could eat 20 carrots, and save that 30 = mins?" Just as I was pouring a glass of milk to go with the two = cupcakes, she grabbed my arm, nearly spilling my milk, and proclaimed, = "I just felt what I thought was an earthquake!" Here it is in her own words: But first, the timeline, and these are fairly accurate and true: 01:12:00 Linda felt the earth move. 01:12:15 Linda got up and walked up to the helicorder and noted the = time, but saw no earthquake signal. 01:14:00 Linda walked upstairs to tell me. 01:16:12 I put down my cupcakes and walked downstairs and saw the = earthquake begin; about 12 seconds of the signal were already traced on = the screen. 01:16:01 The P wave arrived in Boise Idaho. Linda writing: "I was sitting on the couch in the basement when I felt = ever so slightly lightheaded and the couch felt as if the ground swelled = a tiny bit underneath it about 5 or 6 times. The movement was nearly = undetectable (I'm sure if I had been standing or moving around, I would = not have felt it), and the ground swells passed at about the same rate = as a heartbeat. I am confident I really felt something because I = thought to myself, "Huh, how strange this sensation is . . . I wonder = whether that was an earthquake . . . weird, I thought there would be = more distance between waves . . . they are actually pretty close = together, exactly like ripples spreading out in a pond when a stone is = thrown in; it kind of feels like when we used to sit in our sailboat = when the wind was quiet and feel the water gently rock the boat."=20 Is there any kind of wave I would have felt before the P wave actually = arrived? Yes, I was awake, not dreaming! Linda and Ted
This is a new story:   My = wife Linda=20 (IMMG Museum) came upstairs from our basement last night and said she = was sure=20 she felt the earth move!  I was standing in front of the fridge, = looking at=20 the last two cupcakes,  "Should I eat the two cupcakes, or have = some nice=20 carrots?  Let's see, if I choose the cupcakes, I could eat just = one, at 250=20 calories=3D30 mins on the treadmill, or I could eat 20 carrots, and save = that 30=20 mins?"  Just as I was pouring a glass of milk to go with the = two=20 cupcakes, she grabbed my arm, nearly spilling my milk, and = proclaimed, "I=20 just felt what I thought was an earthquake!"
 
Here it is in her own = words:
 
But first, the timeline, and these are = fairly=20 accurate and true:
01:12:00 Linda felt the earth = move.
01:12:15 Linda got up and = walked up to the=20 helicorder and noted the time, but saw no earthquake = signal.
01:14:00 Linda walked upstairs to tell=20 me.
01:16:12 I put down my cupcakes and = walked=20 downstairs and saw the earthquake begin; about 12 seconds of the signal = were=20 already traced on the screen.
01:16:01 The P wave arrived = in Boise=20 Idaho.
 
Linda writing:  "I was sitting on = the couch in=20 the basement when I felt ever so slightly lightheaded and the = couch felt as=20 if the ground swelled a tiny bit underneath it about 5 or 6 = times. =20 The movement was nearly undetectable (I'm sure if I had been standing or = moving=20 around, I would not have felt it), and the ground swells passed at about = the=20 same rate as a heartbeat.  I am confident I really felt something = because I=20 thought to myself, "Huh, how strange this sensation is . . . I wonder = whether=20 that was an earthquake . . . weird, I thought there would be more = distance=20 between waves . . . they are actually pretty close together, = exactly like=20 ripples spreading out in a pond when a stone is thrown in; it kind of = feels like=20 when we used to sit in our sailboat when the wind was quiet and = feel the=20 water gently rock the boat." 
 
Is there any kind of wave I would have = felt before=20 the P wave actually arrived?  Yes, I was awake, not = dreaming!
 
Linda and = Ted
Subject: Re: Did I feel it??? From: Pete Rowe ptrowe@......... Date: Fri, 6 Jul 2007 11:23:19 -0700 (PDT) Ted Before we discuss this further we need the following information: Just how many cupcakes had Linda had? What was in the cupcakes? Perhaps the USGS could buy this recipe from her and finally predict earthquakes??? Enjoy life!!! Pete --- tchannel1@............ wrote: > This is a new story: My wife Linda (IMMG Museum) > came upstairs from our basement last night and said > she was sure she felt the earth move! I was > standing in front of the fridge, looking at the last > two cupcakes, "Should I eat the two cupcakes, or > have some nice carrots? Let's see, if I choose the > cupcakes, I could eat just one, at 250 calories=30 > mins on the treadmill, or I could eat 20 carrots, > and save that 30 mins?" Just as I was pouring a > glass of milk to go with the two cupcakes, she > grabbed my arm, nearly spilling my milk, and > proclaimed, "I just felt what I thought was an > earthquake!" > > Here it is in her own words: > > But first, the timeline, and these are fairly > accurate and true: > 01:12:00 Linda felt the earth move. > 01:12:15 Linda got up and walked up to the > helicorder and noted the time, but saw no earthquake > signal. > 01:14:00 Linda walked upstairs to tell me. > 01:16:12 I put down my cupcakes and walked > downstairs and saw the earthquake begin; about 12 > seconds of the signal were already traced on the > screen. > 01:16:01 The P wave arrived in Boise Idaho. > > Linda writing: "I was sitting on the couch in the > basement when I felt ever so slightly lightheaded > and the couch felt as if the ground swelled a tiny > bit underneath it about 5 or 6 times. The movement > was nearly undetectable (I'm sure if I had been > standing or moving around, I would not have felt > it), and the ground swells passed at about the same > rate as a heartbeat. I am confident I really felt > something because I thought to myself, "Huh, how > strange this sensation is . . . I wonder whether > that was an earthquake . . . weird, I thought there > would be more distance between waves . . . they are > actually pretty close together, exactly like ripples > spreading out in a pond when a stone is thrown in; > it kind of feels like when we used to sit in our > sailboat when the wind was quiet and feel the water > gently rock the boat." > > Is there any kind of wave I would have felt before > the P wave actually arrived? Yes, I was awake, not > dreaming! > > Linda and Ted ____________________________________________________________________________________ Looking for a deal? Find great prices on flights and hotels with Yahoo! FareChase. http://farechase.yahoo.com/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Did I feel it??? From: ChrisAtUpw@....... Date: Fri, 6 Jul 2007 14:44:20 EDT In a message dated 2007/07/06, tchannel1@............ writes: > Is there any kind of wave I would have felt before the P wave actually > arrived? Hi Ted, No, but she may well have experienced a local quake. What was recorded on the seismometer? Remember that you may also feel the effects of wind. Regards, Chris Chapman In a me= ssage dated 2007/07/06, tchannel1@............ writes:

Is there any kind of wave I wou= ld have felt before the P wave actually arrived? 


Hi Ted,

       No, but she may well have experienced a= local quake. What was recorded on the seismometer? Remember that you may al= so feel the effects of wind.

       Regards,

       Chris Chapman Subject: Re: Did I feel it??? From: Mark Robinson mark.robinson@............... Date: Sat, 07 Jul 2007 07:05:15 +1200 tchannel1@............ wrote: > > This is a new story: My wife Linda (IMMG Museum) came upstairs from > our basement last night and said she was sure she felt the earth move! > I was standing in front of the fridge, looking at the last two > cupcakes, "Should I eat the two cupcakes, or have some nice carrots? > Let's see, if I choose the cupcakes, I could eat just one, at 250 > calories=30 mins on the treadmill, or I could eat 20 carrots, and save > that 30 mins?" Just as I was pouring a glass of milk to go with the two > cupcakes, she grabbed my arm, nearly spilling my milk, and > proclaimed, "I just felt what I thought was an earthquake!" > > Here it is in her own words: > > But first, the timeline, and these are fairly accurate and true: > 01:12:00 Linda felt the earth move. > 01:12:15 Linda got up and walked up to the helicorder and noted the > time, but saw no earthquake signal. > 01:14:00 Linda walked upstairs to tell me. > 01:16:12 I put down my cupcakes and walked downstairs and saw the > earthquake begin; about 12 seconds of the signal were already traced on > the screen. > 01:16:01 The P wave arrived in Boise Idaho. > > Linda writing: "I was sitting on the couch in the basement when I felt > ever so slightly lightheaded and the couch felt as if the ground swelled > a tiny bit underneath it about 5 or 6 times. The movement was nearly > undetectable (I'm sure if I had been standing or moving around, I would > not have felt it), and the ground swells passed at about the same rate > as a heartbeat. I am confident I really felt something because I > thought to myself, "Huh, how strange this sensation is . . . I wonder > whether that was an earthquake . . . weird, I thought there would be > more distance between waves . . . they are actually pretty close > together, exactly like ripples spreading out in a pond when a stone is > thrown in; it kind of feels like when we used to sit in our sailboat > when the wind was quiet and feel the water gently rock the boat." > > Is there any kind of wave I would have felt before the P wave actually > arrived? Yes, I was awake, not dreaming! > > Linda and Ted This from the USGS: DELETED: Event UU 07040118 == EVENT DELETED NOTIFICATION == ***This event has been deleted after review by a seismologist.*** Geographic coordinates: 37.539N, 112.508W Magnitude: 1.7 Universal Time (UTC): 4 Jul 2007 01:17:19 Time near the Epicenter: 3 Jul 2007 19:17:19 Location with respect to nearby cities: 11 km (7 miles) NNW (348 degrees) of Alton, UT 14 km (9 miles) SSW (207 degrees) of Hatch, UT 24 km (15 miles) NNE (20 degrees) of Glendale, UT 162 km (100 miles) ENE (59 degrees) of Mesquite, NV 284 km (176 miles) ENE (57 degrees) of Las Vegas, NV Curiouser and curiouser. I've never felt even the smallest quake which didn't show up on the instrumentation and I wouldn't expect to feel a 1.7 unless it was very shallow and right here. -- regards Mark Robinson ------------- 06 Jul 1932 Kenneth Grahame, author of "The Wind in the Willows", died. 06 Jul 1936 Dave Allen born. 06 Jul 1946 Sylvester Stallone born. 06 Jul 1954 Elvis Presley recorded his first single, "That's all right mama" backed with "Blue Moon of Kentucky". It did not chart. 06 Jul 1957 Althea Gibson wins women's title at Wimbledon. 06 Jul 1973 Queen released their first sinlge "Keep yourself alive". 06 Jul 1987 Crowded House meet with Prime Minister David Lange for a chat about about the New Zealand recording industry. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Did I feel it??? From: "Geoffrey" gmvoeth@........... Date: Sat, 7 Jul 2007 04:05:09 -0700 I got news for you. The ladies have great imaginations and I have repeatedly been told that the two remaining females in my family (we are getting old) that they feel earthquakes when I record absolutely nothing. I have noticed in the past that boom like sounds will rattle windows and such and never record as any kind of EQ. I have a suspicion that females are more sensitive than males to vibrations and such and if they have no seismology training want to call just about anything that shake rattles or rolls an Earthquake. It is best to keep your hobby stuff within the realm of those interested in the science or you will be pestered by false alerts...especially when dealing with females. This is just as it seems to me and might not be a reality since it would take a research in Forensic Social-Psychology on this subject of false perceptions to be sure. Regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: The Magic From: tchannel1@............ Date: Sat, 7 Jul 2007 10:43:29 -0600 Hi All, Linda, would not tell me how many cupcakes she ate, and as you = might have guessed they are all gone now. She nor I, have felt anything = that could be considered an earthquake in the last few days. She is often at the computer, by the Sensor, when people visit the = museum. One question she gets, is "How does it work" She understands = how it is built and all the parts, but when the questions focuses on the = magnetic field and the coil, she can only discuss their interaction, = creates a current, like "Magic" I have seen a formula explaining the three factors, The Field, The Coil, = and The Velocity.......... Could someone tell me or direct me to an explanation of "The Magic" = which is really the basic for this type of sensor. Thanks, Ted
Hi All,  Linda, would not tell me = how many=20 cupcakes she ate, and as you might have guessed they are all gone=20 now.  She nor I, have felt anything that could be considered = an=20 earthquake in the last few days.
 
She is often at the computer, by the = Sensor, when=20 people visit the museum.  One question she gets, is "How does it=20 work"  She understands how it is built and all the parts, but when = the=20 questions focuses on the magnetic field and the coil, she can only = discuss their=20 interaction, creates a current, like "Magic"
 
I have seen a formula explaining the = three factors,=20 The Field, The Coil, and The Velocity..........
Could someone tell me or direct me to = an=20 explanation of "The Magic"  which is really the basic for this type = of=20 sensor.
 
Thanks, Ted
Subject: Re: The Magic From: ChrisAtUpw@....... Date: Sat, 7 Jul 2007 18:53:23 EDT In a message dated 2007/07/07, tchannel1@............ writes: > She is often at the computer, by the Sensor, when people visit the museum. > One question she gets, is "How does it work" She understands how it is > built and all the parts, but when the questions focuses on the magnetic field and > the coil, she can only discuss their interaction, creates a current, like > "Magic" Hi Ted, Movement of a coil in a magnetic changing field does not produce a current, but a voltage across the ends of the coil. This voltage is proportional to the number of turns, to the area of the coil and to the rate of change of the field. A current flowing in a conductor has a ring magnetic field assocciated with it. If you use a circular solenoid, the turns add up to give an axial agnetic field. I use a school demo system having quad NdFeB magnets on two parallel mild steel backplates. I use a relay coil on a handle connected to back to back red and green LEDs. You move the coil one way and the red LED lights, the other way and the green LED lights. If you move the coil more rapidly, the LEDs glow a lot brighter. Why not make up a similar model for the museum? > I have seen a formula explaining the three factors, The Field, The Coil, > and The Velocity.......... > Could someone tell me or direct me to an explanation of "The Magic" which > is really the basic for this type of sensor. Regards, Chris Chapman In a me= ssage dated 2007/07/07, tchannel1@............ writes:

She is often at the computer, b= y the Sensor, when people visit the museum.  One question she gets, is=20= "How does it work"  She understands how it is built and all the parts,=20= but when the questions focuses on the magnetic field and the coil, she can o= nly discuss their interaction, creates a current, like "Magic"

Hi Ted,
      
       Movement of a coil in a magnetic changi= ng field does not produce a current, but a voltage across the ends of the co= il. This voltage is proportional to the number of turns, to the area of the=20= coil and to the rate of change of the field.
       A current flowing in a conductor has a=20= ring magnetic field assocciated with it. If you use a circular solenoid, the= turns add up to give an axial agnetic field.

    I use a school demo system having quad NdFeB magnets=20= on two parallel mild steel backplates. I use a relay coil on a handle connec= ted to back to back red and green LEDs. You move the coil one way and the re= d LED lights, the other way and the green LED lights. If you move the coil m= ore rapidly, the LEDs glow a lot brighter. Why not make up a similar model f= or the museum?

I have seen a formula explain= ing the three factors, The Field, The Coil, and The Velocity..........
Could someone tell me or direct me to an explanation of "The Magic"  w= hich is really the basic for this type of sensor.


       Regards,

       Chris Chapman Subject: Re: The Magic From: tchannel1@............ Date: Sat, 7 Jul 2007 17:52:53 -0600 Hi Chris, That is a good idea..........The visitors to the Museum are = mostly tour groups of kids...They love to touch things, and maybe I = could work something like this up. I think that would explain the = Magic very well. Thanks, Ted ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Saturday, July 07, 2007 4:53 PM Subject: Re: The Magic In a message dated 2007/07/07, tchannel1@............ writes: She is often at the computer, by the Sensor, when people visit the = museum. One question she gets, is "How does it work" She understands = how it is built and all the parts, but when the questions focuses on the = magnetic field and the coil, she can only discuss their interaction, = creates a current, like "Magic" Hi Ted,=20 =20 Movement of a coil in a magnetic changing field does not = produce a current, but a voltage across the ends of the coil. This = voltage is proportional to the number of turns, to the area of the coil = and to the rate of change of the field.=20 A current flowing in a conductor has a ring magnetic field = assocciated with it. If you use a circular solenoid, the turns add up to = give an axial agnetic field. I use a school demo system having quad NdFeB magnets on two = parallel mild steel backplates. I use a relay coil on a handle connected = to back to back red and green LEDs. You move the coil one way and the = red LED lights, the other way and the green LED lights. If you move the = coil more rapidly, the LEDs glow a lot brighter. Why not make up a = similar model for the museum? I have seen a formula explaining the three factors, The Field, The = Coil, and The Velocity.......... Could someone tell me or direct me to an explanation of "The Magic" = which is really the basic for this type of sensor. Regards, Chris Chapman
Hi Chris,  That is a good = idea..........The=20 visitors to the Museum are mostly tour groups of kids...They love to = touch=20 things, and maybe I could work something like this up.   I = think that=20 would explain the Magic very well.
Thanks, Ted
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Saturday, July 07, 2007 = 4:53=20 PM
Subject: Re: The Magic

In a=20 message dated 2007/07/07, tchannel1@............=20 writes:

She is often at the computer, by the Sensor, when people = visit=20 the museum.  One question she gets, is "How does it work"  = She=20 understands how it is built and all the parts, but when the = questions=20 focuses on the magnetic field and the coil, she can only discuss = their=20 interaction, creates a current, like "Magic"


Hi Ted,=20
      =20
       Movement of a coil in a = magnetic=20 changing field does not produce a current, but a voltage across the = ends of=20 the coil. This voltage is proportional to the number of turns, to the = area of=20 the coil and to the rate of change of the field.=20
       A current flowing in a = conductor has=20 a ring magnetic field assocciated with it. If you use a circular = solenoid, the=20 turns add up to give an axial agnetic field.

    = I use a school demo system = having quad NdFeB=20 magnets on two parallel mild steel backplates. I use a relay coil on a = handle=20 connected to back to back red and green LEDs. You move the coil one = way and=20 the red LED lights, the other way and the green LED lights. If you = move the=20 coil more rapidly, the LEDs glow a lot brighter. Why not make up a = similar=20 model for the museum?

I have=20 seen a formula explaining the three factors, The Field, The Coil, = and The=20 Velocity..........
Could someone tell me or direct me to an = explanation of "The=20 Magic"  which is really the basic for this type of=20 sensor.

      =20 Regards,

       Chris = Chapman=20 Subject: Re: The Magic From: ChrisAtUpw@....... Date: Sun, 8 Jul 2007 00:55:45 EDT In a message dated 2007/07/08 , tchannel1@............ writes: > Hi Chris, That is a good idea..........The visitors to the Museum are > mostly tour groups of kids...They love to touch things, and maybe I could work > something like this up. I think that would explain the Magic very well. > Thanks, Ted Hi Ted, See the drawing at http://jclahr.com/science/psn/chapman/lehman/LehmanNdFeBSensor2.jpg for the basic idea. Regards, Chris In a me= ssage dated 2007/07/08 , tchannel1@............ writes:

Hi Chris,  That is a good=20= idea..........The visitors to the Museum are mostly tour groups of kids...Th= ey love to touch things, and maybe I could work something like this up. = ;  I think that would explain the Magic very well.
Thanks, Ted


Hi Ted,

       See the drawing at http://jclahr.com/sc= ience/psn/chapman/lehman/LehmanNdFeBSensor2.jpg for the basic idea.

       Regards,

       Chris Subject: Most Recent Discover Magazine pp66-67 WaterFall Display From: "Geoffrey" gmvoeth@........... Date: Sat, 7 Jul 2007 21:59:12 -0700 Hi All You PSN Fanatics (Im One Too); Here is a scientific example of a waterfall display that might be usful in one way or another to us Amateures. The only differences are that the time needs to be on the Y axis and Freq. on the X axis. In Science/Math time is always assigned to X axis but in reality you make it to suit your own tastes according to importance. This amounts to signature analysis where the data forms a picture. Over time you build a database of known events so that in the future you can simply look at the signature to tell pretty much what your looking at and give the event a classification. Black and White and shades of gray are better than this colorful stuff because not all people (especially males) have perfect color vision. There should be a range of signatures for events such as tornadoes and hurricanse and wave action and seismic events. You most probably do not need more than 1024 discrete frequencies and in an fft algorithim the number of samples you use in your conversion determins the frequency resolution. the FFT is an energy thing I think meaning the area under a curve. It can be of use to us if amateures are serious minded hobbiests. I lack the ability to program or I would do this myself. This is sort of a challange to all you amateures to develop a program that will take text or raw data in the form of bytes or words or text to make a water fall display in B/W 16 shades of gray with each time frame jumping only one sample at a time. Distrubute this analysis program freely to all seismic amateures and build a data base of known signatures that can be used by anyone in the PSN. Regards; Geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Most Recent Discover Magazine pp66-67 WaterFall Display From: ChrisAtUpw@....... Date: Sun, 8 Jul 2007 06:46:29 EDT In a message dated 2007/07/08, gmvoeth@........... writes: > Hi All You PSN Fanatics (Im One Too); > Here is a scientific example of a waterfall display > that might be usful in one way or another to us > Amateures. The only differences are that the > time needs to be on the Y axis and Freq. > on the X axis. In Science/Math time is always assigned to > X axis but in reality you make it to suit your own tastes > according to importance. Alternatively convert your files to a format which can be read by such a program? I seem to remember that this has been done? See http://www.radiosky.com/skypipeishere.html Why use B/W when color gives a better display? Regards, Chris Chapman In a me= ssage dated 2007/07/08, gmvoeth@........... writes:

Hi All You PSN Fanatics (Im One= Too);
Here is a scientific example of a waterfall display
that might be usful in one way or another to us
Amateures. The only differences are that the
time needs to be on the Y axis and Freq.
on the X axis. In Science/Math time is always assigned to
X axis but in reality you make it to suit your own tastes
according to importance.


       Alternatively convert your files to a f= ormat which can be read by such a program? I seem to remember that this has=20= been done?  See = http://www.radiosky.com/skypipeishere.html
       Why use B/W when color gives a better d= isplay?

       Regards,

       Chris Chapman Subject: Re: Most Recent Discover Magazine pp66-67 WaterFall Display From: "Geoffrey" gmvoeth@........... Date: Sun, 8 Jul 2007 07:01:56 -0700 This program seems to not use data files but wants you to build a custom A/D that will be read by the program itself. Not sure a sound card will take sample rates as low as 20Hz because most sound hardware has a capacitor input that rejects DC or freqs below the sense of hearing. It would be so nice to have this feature in Winquake to do an Analysis of file data in TXT/8/12/16/24 bit form or text form all you have to do is limit the frq between Dc and 5 Hz or so and make atleast 1024 samples per spectrum line. I have seen the routine in the library at ASU to FFT and there seems to be several ways. The best i like seems to result in the final results with the number of samples to be worked setting the resolution over the band. These people who write these books on FFT are oriented only to their own kind so if you do not know calculus or higher transforming their ideas into a computer program is very difficult. But I have in the past done this successfully myself. On a very small scale with a VIC20 machine running 10MHz. You need to take the first 1024 samples then make an imaginary set from the same ones then do a butterfly operation (some kind of fancy math) that results in a backward spectrum with each sample now representing a frequency band. Then you straighten out the results to get the low freq at the low sample number position. The final results is the freq range represented within the sample set chosen and that would be line one. Then you advance one sample in the data and do the same for the next contiguous 1024 samples. This is repeated until you have built a picture of your entire data file. The sample rate determins the freq limits I think. Why do not more people take an interest in the math and programming and hardware because seismology is just a fine specialty and I think more serious PROs should take an interest in fostering human interests in all lines of Science. You got to be an MD or equiv before you can get into forensic medicine ot Toxicology but this Seismology stuff is non license stuff and great way to learn many facets of science. Please someone with Math background make us a Basic Program like QBASIC or POWERBASIC to do one line of FFT and I will take it from there to make the whole program. I did this once myself but did not record the final program and would have to learn everything all over again to do this program again. A Burgler stole the VIC20 laptop with all my programs several years ago so those programs are lost. There is more to amateur stuff then just watching the waves and building things with your hands. It is a great chance to play general science and bring most everything together to see how it works with NO MYSTRIES. There seems to be effort to compartmentize information in the USA because of its capitalistic nature forcing one to become a college goon before you are able to do anything academic. The truth of the matter is to get a formal degree the system studies you as much as you study your subject so there is no real privacy or artisic freedom for the adventerous academic without government awareness. The Counter Intelligence peoples do not want Academic Freedom in the USA. Even tho we are playing with this harmless passive seismology stuff. I have come to realize that in some European Countries they have laws amounting to NEPLEONIC LAW which basically says everything is illegal except that which is specified by government. These kinds of forces are what we up against even in this relatively harmless area of seismology. If there is no common place to get knowledge we must make it ourselves even if it angers the powers that be. It is no accident we can not find a simple BASIC FFT source code with logic trees etc in laymen terms for our interest area. Everyone is trying to keep secrets or make money. For the sake of the evolution of science lets please gather together a collection of utility programs free for universal use in this PSN group. I am assuming PSN means Public like WORLD PUBLIC and not just California Public. One LAST thing for NOW. Black and White and shades of gray is by far the best for resolution and universal readability. If a person is lucky to get a totally black and white monitor or green you will see no sharper images than with such an analog electrostatic scanning device. The military used to preferr these over color since it used to be all male (for warships) and males have the highest incident of color blindness. Regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Most Recent Discover Magazine pp66-67 WaterFall Display From: ChrisAtUpw@....... Date: Sun, 8 Jul 2007 10:45:54 EDT In a message dated 2007/07/08, gmvoeth@........... writes: > This program seems to not use data files but wants you to build a custom > A/D that > will be read by the program itself. Hi Geoff, I am absolutely certain that I have seen seismic data on waterfall displays, but I can't remeber where. Certainly they were on line. That program will take binary data files, like amaseis? Have a look at www.vlf.it ? Regards, Chris Chapman In a me= ssage dated 2007/07/08, gmvoeth@........... writes:

This program seems to not use d= ata files but wants you to build a custom A/D that
will be read by the program itself.


Hi Geoff,

       I am absolutely certain that I have see= n seismic data on waterfall displays, but I can't remeber where. Certainly t= hey were on line. That program will take binary data files, like amaseis?
       Have a look at www.vlf.it ?

       Regards,

       Chris Chapman Subject: Re: Most Recent Discover Magazine pp66-67 WaterFall Display From: Mike Price mprice@........ Date: Sun, 08 Jul 2007 11:39:07 -0700 Geoff, The FFT algorithm is well documented and implementations abound. The FFT is widely used by anyone interested in exploring data in the frequency domain and it would be hard to find an algorithm better explained or more readily available. A Google search for "fft source code" generates 1.3M hits; indeed, the first one is www.fftw.org which has downloadable C source and links to many other sites containing source in several languages. You can find a basic implementation at: http://logosfoundation.org/fft/fft.html for example. The notion that access to FFT code is somehow restricted is misguided. Mike Geoffrey wrote: > This program seems to not use data files > but wants you to build a custom A/D that > will be read by the program itself. > Not sure a sound card will take sample rates > as low as 20Hz because most sound hardware > has a capacitor input that rejects DC or freqs > below the sense of hearing. > > It would be so nice to have this feature in Winquake to > do an Analysis of file data in TXT/8/12/16/24 bit form > or text form all you have to do is limit the frq > between Dc and 5 Hz or so and make atleast > 1024 samples per spectrum line. > > I have seen the routine in the library at ASU > to FFT and there seems to be several ways. > The best i like seems to result in the final > results with the number of samples to be worked > setting the resolution over the band. > > These people who write these books on FFT are oriented > only to their own kind so if you do not know calculus or higher > transforming their ideas into a computer program is very difficult. > > But I have in the past done this successfully myself. > On a very small scale with a VIC20 machine running 10MHz. > > You need to take the first 1024 samples then make an imaginary > set from the same ones then do a butterfly operation > (some kind of fancy math) that results in a backward > spectrum with each sample now representing a frequency band. > > Then you straighten out the results to get the low freq at the low > sample number position. > > The final results is the freq range represented within the sample set > chosen > and that would be line one. > > Then you advance one sample in the data and do the same for the > next contiguous 1024 samples. > > This is repeated until you have built a picture of your entire data file. > > The sample rate determins the freq limits I think. > > Why do not more people take an interest > in the math and programming and hardware > because seismology is just a fine specialty > and I think more serious PROs should take an > interest in fostering human interests in all lines of Science. > > You got to be an MD or equiv before you can > get into forensic medicine ot Toxicology but this > Seismology stuff is non license stuff and great way to > learn many facets of science. > > Please someone with Math background make us a > Basic Program like QBASIC or POWERBASIC > to do one line of FFT and I will take it from there > to make the whole program. > > I did this once myself but did not record the final > program and would have to learn everything all over > again to do this program again. > A Burgler stole the VIC20 laptop with all my programs > several years ago so those programs are lost. > > There is more to amateur stuff then just watching the waves > and building things with your hands. It is a great chance > to play general science and bring most everything together > to see how it works with NO MYSTRIES. > > There seems to be effort to compartmentize information > in the USA because of its capitalistic nature forcing one > to become a college goon before you are able to > do anything academic. The truth of the matter > is to get a formal degree the system studies you as much > as you study your subject so there is no real privacy > or artisic freedom for the adventerous academic without > government awareness. The Counter Intelligence peoples > do not want Academic Freedom in the USA. > Even tho we are playing with this harmless passive seismology stuff. > > I have come to realize that in some European Countries > they have laws amounting to NEPLEONIC LAW which basically > says everything is illegal except that which is specified by government. > > These kinds of forces are what we up against even in this > relatively harmless area of seismology. > > If there is no common place to get knowledge we must make it ourselves > even if it angers the powers that be. > > It is no accident we can not find a simple BASIC FFT source code > with logic trees etc in laymen terms for our interest area. > Everyone is trying to keep secrets or make money. > > For the sake of the evolution of science lets > please gather together a collection of utility programs > free for universal use in this PSN group. > > I am assuming PSN means Public like WORLD PUBLIC and not just > California Public. > > One LAST thing for NOW. > Black and White and shades of gray is by far the best for resolution > and universal readability. > If a person is lucky to get a totally black and white monitor or green > you will see no sharper images than with such an analog electrostatic > scanning device. > The military used to preferr these over color since it used to be all > male > (for warships) > and males have the highest incident of color blindness. > > Regards; > geoff > __________________________________________________________ > > 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: FFT BASIC Source Code From: "Geoffrey" gmvoeth@........... Date: Sun, 8 Jul 2007 12:41:22 -0700 Hello PSN; I found my very old notes from ASU Nobel Science Library regarding FFT basic program and I think it shows the source material it was found in. Can someone who understands FFT please look at this and comment to me at my address gmvoeth@........... or to PSN or to Both. I intend to make a DOS executable program to use 8 bit data that will display the results in 640X480X256 if at all possible. I will share my results if things look good. The only question I have is that about real and imaginary. I assume real means sine of the data and imaginary means cosine of the data and the angle relates to the sample rate vs the desired frequency and summed acxcording to the sample number and that the complete butterfly operation needs to be done 1024 times for each desired freq to look at. The bandwidth of each freq will be related to the number of samples processed. What I do not understand is how can you measure frequency unless you start out in phase with the freq you are looking for ?? Basic Source code for the FFT is very hard to find. Out of that whole library in the 1980s this is the only basic example I found. Maybe one of you experts can tell me if this program is honestly workable and the results will be proper ? I understand to save space you can use the same memory locations as the original data to put the results into but it (results) will be reversed and you need to start your freq display using the highest result (N) as the lowest Frq in the display (N). This computation although it is called FFT is very labor intensive and the time will increase exponentially to get the results according to the number of samples you process each line. If Im not mistaken it took me several minutes with the 10MHz VIC20 chip CPU to complete a single spectrum line using only 1024 samples. Today my machine is P4 3GHz so I should expect seconds instead of minutes. Notes: ***************************** http://gmvoeth.home.mchsi.com/FFT_Basic_Source.bmp ****************************** Regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: FFT Waterfall display From: Larry Conklin lconklin@............ Date: Sun, 08 Jul 2007 15:56:30 -0400 A couple of years ago I experimented with adding a real-time FFT waterfall display to my home brew data logging and display program. I got the waterfall working just fine but there is something wrong with the FFT calculation that I never got around to debugging. The current discussion may motivate me to take another look at it. If I manage to get something working, it wouldn't be much additional effort to adapt the code into an independent program that would take PSN files as a data source. Larry Conklin Liverpool, NY lconklin@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Most Recent Discover Magazine pp66-67 WaterFall Display From: "Geoffrey" gmvoeth@........... Date: Sun, 8 Jul 2007 13:36:02 -0700 Wonderful and thanks; It has been a few years since I looked and I never found anything like that. It (FFT) was classified Secret in the US Navy in the 1970s but after I saw my "secret" machine sold to foreign countries in a commissiond officers magazine (My dad was a retired officer) I no longer accepted the navys classification. for that machine. I now realize they want to keep it a secret only till they market the machine wherever. The secrecy is more for economic (manufacturing) than military reasons. We were probably only testing the device for Diagnostic Retreival Company. A general purpose computer like mine that works in a serial fashion can not match the speed of that parallel computing machine. The macine in question was the AN/SQR17 which did all this stuff in almost real time through dedicated circuitry. They used it in conjunction with the SKR4 telemetric receiver which was relayed sonobuoy data through the LAMPS helicopter. This machine SQR17 was all blue and blue means training and not war stuff. AN means Joint Army Navy which means the electronic circuitry is standard to both services. Everything I know is from 1970s and then it was old news so I am not worrying too much about talking today. One of my My old Ships the USS LONG BEACH is now atomic razor blades. The other Two Ellison and Willard Keith were sold to Turkey or South America and the only remaining one still alive might be the very old Bainbridge. I was on three of the several nuclear surface ships the only one i never boarded was the Truxton. I think you will not see any more because nuclear power is quite dangerous those ships are very fragile. It was funny when the russian trawlers would pick up the sonobuoys and you could hear them mutter over what they just found in their nets. Wish I could understand their words. Something like "More Alien Crap from the ocean". :-) I am now called Mentally Ill by the USA even tho I feel just the same now as when I was 17 and in Great Lakes Illinoise being poisoned with flouride treatment by a bad bad Dental Technician. Over xrayed by bad bad xray technicians. Even had to drink JP5 in our water once. Forced to go to etiquitte training because refused to go to church. I find it amazing we enlisted squids live as long as we do to enjoy any seismology at all. USW...the classification goes something like this: Confidential==Capabilities and limitations frequencies technical stuff etc.. (just about everyone) Secret==those things that might cause harm to the USA (Enlisted Stuff) Top Secret==those things that will cause harm to the USA (Commissioned Officers) Other agencies use different terms for the same ideas or spell out the dangers involved. I have never seen anything that was called top secret and only those things i needed to know at those times. I feel I have no knowledge valuable to the USA today. Everything I can think of except intellegence data bases is obsolete. And those are Protected libraries I no longer have access to. But we can make and share our own seismic stuff. In case you are wondering about my loyalties; I love MY Country (The one with Protected InAlienable Rights). regards; geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: FFT BASIC Source Code From: Ben Bradley benbradley@............... Date: Sun, 08 Jul 2007 17:58:17 -0500 Geoffrey wrote: > Hello PSN; > > I found my very old notes from ASU Nobel Science Library regarding > FFT basic program and I think it shows > the source material it was found in. > > Can someone who understands FFT please look at this > and comment to me at my address gmvoeth@........... or to PSN or to Both. You can get a better understanding of the Fourier Transform and FFT from many places online. Here's one: http://www.dspguide.com/ > > I intend to make a DOS executable program to use > 8 bit data that will display the results in 640X480X256 if at all > possible. I will share my results if things look good. > > The only question I have is that about real and imaginary. > > I assume real means sine of the data and imaginary means cosine of the > data As I recall, Cosine is the "real" part and Sine is the "Imaginary" part. > and the angle relates to the sample rate vs the desired frequency and > summed acxcording to the sample number and that the complete butterfly > operation needs > to be done 1024 times for each desired freq to look at. > The bandwidth of each freq will be related to the number of samples > processed. What I do not understand is how > can you measure frequency unless you start out in phase > with the freq you are looking for ?? The complex Fourier Transform tells you both the frequency and the phase. It may seem like magic, but there's a graphical way of understanding it. > > Basic Source code for the FFT is very hard to find. I suppose BASIC is now considered obsolete, except for some of the Visual Basics found in Microsoft products, and even those may have been phased out by now. > > Out of that whole library in the 1980s this is the only basic example > I found. > > Maybe one of you experts can tell me if this program is honestly workable > and the results will be proper ? > > I understand to save space you can use > the same memory locations as the original data > to put the results into but it (results) will be reversed > and you need to start your freq display using the highest > result (N) as the lowest Frq in the display (N). > > This computation although it is called FFT is very > labor intensive and the time will increase exponentially > to get the results according to the number of samples > you process each line. > > If Im not mistaken it took me several minutes with the 10MHz VIC20 > chip CPU > to complete a single spectrum line using only 1024 samples. > Today my machine is P4 3GHz so I should expect seconds instead of > minutes. An optimized, compiled program on a modern PC should be able to do a 1024 point complex FFT in a very few milliseconds. This speed is helpful if you want to create waterfall plots, which (as I understand it) are made with many repeated FFT's over time. > > Notes: > ***************************** > http://gmvoeth.home.mchsi.com/FFT_Basic_Source.bmp Actually, that's a FORTRAN source. Offhand it looks okay to me, but don't take my word for it. > > ****************************** > > Regards; > geoff __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Most Recent Discover Magazine pp66-67 WaterFall Display From: Mike Price mprice@........ Date: Sun, 08 Jul 2007 16:06:31 -0700 Geoff, A 3.2 GHz Pentium 4 with a vectorized FFT implementation using SSE2 (special extended 128-bit MMX instruction set of the Pentium) can execute a 1024 point FFT in well under 1mS. A 4096 FFT can be executed in under 6mS. This would blow the doors off any ca. 1972 implementation even if done entirely in HW. The number of points needed in an FFT is driven by the desired frequency resolution (bin width = sample_frequency / number_of_points). You may be able to get away with fewer number of points if you don't need fine frequency resolution. The FFT produces a complex number: a + bi. Think of it as a vector. You get magnitude and phase as follows: mag = sqrt( a^2 + b^2 ) phase = atan ( b / a ) Mike Price Geoffrey wrote: > Wonderful and thanks; > It has been a few years since I looked > and I never found anything like that. > > It (FFT) was classified Secret in the US Navy in the 1970s > but after I saw my "secret" machine sold to foreign > countries in a commissiond officers magazine > (My dad was a retired officer) I no longer accepted the navys > classification. > for that machine. > I now realize they want to keep it a secret > only till they market the machine wherever. > The secrecy is more for economic (manufacturing) > than military reasons. We were probably only > testing the device for Diagnostic Retreival Company. > > A general purpose computer like mine