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  12047   Fri Mar 25 19:17:28 2016 NikhilUpdatePEMGuralp Seismometers

Calibration of Guralp Seismometers

Objective

  • Estimate transfer functions of Guralp A ( near ETMX) and Guralp B ( near ETMY)
  • Calibrate the instruments by estimating Velocity Sensitity Parameter
  • Convert previously measured Voltage Spectrum to Velocity Spectrum

Instruments Used

  • Guralp CMG-40 T Seimometers  : Guralp A (Serial Number: T4Q17)
  • Guralp CMG-40 T Seimometers  : Guralp B (Serial Number: T4157)
  • Guralp Handheld Control Unit (HCU)
  • FFT Spectrum Analyzer: Model SR785: 2 Channel Dynamic Signal Analyzer
  • Oscilloscope: TDS 3014B
  • Function Generator: DS 345

Procedure & Results

Sinusoidal current of known frequency and amplitude was injected to the Seismometer calibration coil using signal generator and handheld control unit & corresponding Magnitude and Phase response were recorded.  For  Guralp B, system response was also estimated with a FFT Spectrum Analyzer. 

 

    

Frequnecy Range: 0.1 Hz to 45 Hz.

Equivalent Input Velocity was derived from the Input Voltage measurements using the relation: v = V/ (2*pi*f*R*K) , V is the peak to peak Calibration Signal voltage, f is the calibration signal frequency, R is the calibration resistor and K is the feedback coil constant.  [See Appendix for R & K values]                                     

Velocity Sensitity at the required frequency is obtained by dividing the Output Response Voltage by the Equivalent Input Velocity.

               

The obtained Velocity Sensitivity is used to convert the recorded Volatge PSD to Velocity PSD as shown below. The obtained results are compared to gloabl high noise model [NHNM] and USGS New Low Noise Model [NLNM,Peterson 1993] which gives the lowest observed vertical seismic noise levels across the seismic frequency band. Plot legend NLNM shows both the high & low levels.

 

                                                                    Guralp A [X Arm] Low Velocity Output                                          

                  

                                                                    Guralp B [Y Arm] Low Velocity Output                                          

            

                                                                            DTT Power Spectrum                                                             

Both the Seismometers were connected to the 40 M Control and Data Acquisition System (CDS) and Power Spectrum was estimated for the Vertical, North/South & East/West Channels using Diagnostic Test Tool (DTT) software.

                                                            

Comments

  •  The transfer function from Guralp A [ETMX] looks similar to that of Guralp B [ETMY] in both magnitude and phase but with a lower gain.                                                                                                                                                                                                  
  • Velocity Sensitivity of Guralp A is comparable to the value provided in the Calibration Data Sheet [~ 400] for all the channels [Vertical, North/South, East/West] after 1 Hz. For Guralp B, Velocity Sensitivity is a factor of 2.5 higher [all channels] than the specification [~ 400] after 1 HZ.Below 1 Hz Sensitivity drops down for both sensors. I am not ruling out a missing common factor in the calculation, but anyway, test shows that Guralp B has ~2.5 times better Velocity Sensitivity than Guralp A.                                                                                                                                                               
  • The Calibrated Seismic Velocity Spectrum for Guralp B is within the Globally Observed High and Low Noise Seismic Spectrum while Guralp A's Spectrum is more noisier above 1 Hz [Anthropogenic Activity normally contributes the most in 1 Hz to 10 Hz frequency band].                                                                                                                                                                                                                                                                          
  • Concurrently acquired Power Spectrum using DTT [Diagnostic Test Tools] shows that Guralp A Spectrum behaves rather strangely. The system response seems to be completely different from the one we obtained locally using signal generator. While Guralp B functionality seems normal. One reason for this erratic beahvior might be faulty cables used for data acquisition from Guralp A. This needs to be verified.                                                                                                                        

Appendix

                                                                            CMG-40T Guralp A Calibration Sheet                                                           

  Velocity Output: V/m/s (Differential) Mass Position Output (Acceleration Output) : V/m/s^2  Feedback Coil Constant : Amp/m/s^2
Vertical 2 x 400 19 0.00397
North/South 2 x 398 23 0.00486
East/West 2 x 401 23 0.00479                 

Calibration Resistor: 51000

                                                                            CMG-40T Guralp B Calibration Sheet                                                           

  Velocity Output: V/m/s (Differential) Mass Position Output (Acceleration Output) : V/m/s^2  Feedback Coil Constant : Amp/m/s^2
Vertical 2 x 401 19 0.00408
North/South 2 x 400 20 0.00421
East/West 2 x 404 22

0.00466

Calibration Resistor: 51000 

Attachment 3: VelSens_XArm_Guralp_A.png
VelSens_XArm_Guralp_A.png
Attachment 4: VelSens_XArm_Guralp_A.png
VelSens_XArm_Guralp_A.png
Attachment 5: VelSens_YArm_Guralp_B.png
VelSens_YArm_Guralp_B.png
Attachment 8: Vel_PSD_XArm_GurB_E.png
Vel_PSD_XArm_GurB_E.png
Attachment 9: Vel_PSD_XArm_GurB_N.png
Vel_PSD_XArm_GurB_N.png
Attachment 16: Guralp_PowerSpectrum.pdf
Guralp_PowerSpectrum.pdf
  12048   Fri Mar 25 23:54:04 2016 ranaUpdatePEMGuralp Seismometers

Something seems not right. The Guralp response should be flat in velocity from 0.05-30 Hz. Why is there any feature at 1 Hz? Saturation of some kind?

  1885   Tue Aug 11 02:15:20 2009 ClaraUpdatePEMGuralp breakout box circuit diagram

While writing my progress report, I redrew the Guralp breakout box circuit diagram with all the changes marked. Since only one hard copy exists, I thought it might be useful to post my drawing up in case it is needed for any reason. The two drawings are the same - the second has just been broken into two parts to make it easier to fit on a normal 8.5 x 11 or A4 sheet of paper. The gains for each opamp have not been marked, but they could very easily be added in if necessary. The black resistances and capacitances are the originals. All changes have been indicated in blue.

Guralp_circuit_whole.png

Guralp_circuit_broken.png

  1859   Fri Aug 7 16:53:35 2009 ClaraUpdatePEMGuralp breakout box noise, finally

After many issues, I finally have some Guralp box noise. I did not measure every single channel with high resolution at the low frequencies because that would have taken about 3 years, but I could perhaps take some faster measurements for all of them if necessary.

output_vallwr2_ns3_1.png

tp3gnd_vallwr2_ns3.png

  11290   Wed May 13 13:33:34 2015 SteveFrogsPEMGuralp breakout box recovered

COD_Sugar napolion is due to Steve:  Item delivered, model CMG-SCU-0013, sn G9536

Quote:

Reward being offered for the safe return of this thing:

 

  11289   Wed May 13 10:07:36 2015 ranaFrogsPEMGuralp breakout paddle

Reward being offered for the safe return of this thing:

  10776   Wed Dec 10 21:05:56 2014 KateUpdateSEIGuralp briefly powered down

 Kate & Jenne

About 2:30 this afternoon, we briefly powered off the Guralp (C1:PEM-SEIS_GUR1_{X,Y,Z}) in order to better align it with the other seismometers along its marked N/S direction. It had been visibly off by a few degrees. 

  1540   Sat May 2 16:34:31 2009 carynDAQPEMGuralp channels plugged back in

I plugged the Guralp cables back into the PEM ADCU

       Guralp NS1b ---> #11

       Guralp Vert1b --->#10

       Guralp EW1b --->#12

  9699   Thu Mar 6 11:43:17 2014 steveUpdateGeneralGuralp control unit

CMG-40T handheld controller unit is missing its power supply. In order to zero the instrument one has to apply plus and minus DC voltage.

The wiring on this 10 pin Amphenol PT02E-12-10P is shown.

Attachment 1: GuralpCU.jpg
GuralpCU.jpg
Attachment 2: BAH.jpg
BAH.jpg
  2743   Wed Mar 31 16:31:44 2010 steveUpdatePEMGuralp interface box turned off

Quote:

Quote:

I went and double-checked and aligned the styrofoam cooler at ~5:00 UTC. It was fine, but we really need a better huddling box. Where's that granite anyway?

Here's the new Huddle Test output. This time I show the X-axis since there's some coherence now below 0.1 Hz.

You'll also notice that the Wiener filter is now beating the FD subtraction. This happened when I increased the # of taps to 8000. Looks like the noise keeps getting lower as I increase the number of taps, but this is really a kind of cheat if you think about it carefully.

 The same thing happening again.  The intermittent offset upstream of the seismometer that never got fixed.

The granite plate and ball bearings are in. I will place seismometers on it.

 

Attachment 1: grlpntrfcbxoff.jpg
grlpntrfcbxoff.jpg
  2764   Mon Apr 5 01:02:07 2010 ranaUpdatePEMGuralp interface box turned off

I was checking into the Guralp situation today. I put the rubber balls underneath the granite block (the Q is too high), but found unfortunately that Jenne's styrofoam box is too short to cover the Guralps on top of the granite. If the box was skinny enough to fit on the block or taller by ~6 inches, it would be perfect. We need some new Seismo boxes.

 

Here's the story of the Gur2 noise so far. We need to pull out and repair the breakout box.

1) At some point we noticed that the Guralp2 X channel was behaving badly.

2) Steve tried recentering with just a +12V supply - this didn't work. Jenne then centered it using the +/- 12V supply. This was OK.

3) Around noon on March 24, the channel 'goes bad' again.

4) On the afternoon of the 25th, most of the channels go to zero, but the GUR2X channel stays bad. There's NO ENTRY in the elog about this. This is UNACCEPTABLE. Apparently, the seismometers were disconnected without shutting off the power to the box. You MUST elog everything - otherwise, go home and sit on your hands.

5) On the evening of the 31st, Steve turns off the Guralp breakout box. From the trend, you can see that the signals all go to zero at that time.

6) From then until today, there is no noise in the GUR2X channel. From these tests we can guess that the problem is in the GUR2X channel of the breakout box, but not in the AA Chassis or the ADC, since those showed no excess noise with the box turned OFF. Its hard to be sure without elog entries, but I assume that 3/25-3/31 was a 'seismometer disconnected', but 'box on' state.

Attachment 1: Untitled.png
Untitled.png
  1453   Fri Apr 3 14:52:38 2009 JenneOmnistructurePEMGuralp is finally back!

After many, many "it'll be there in 2 weeks" from the Guralp people, our seismometer is finally back!

I have it plugged into the Guralp breakout box's Channel 1xyz (so I have unplugged the other Guralp).  Both of the Guralp's are currently sitting under the MC1/MC3 chamber.

Before we can have both Guralps up and running, I need to stuff the next 3 channels of the breakout box (back in the fall, I only had Caryn do 1x, 1y, 1z, and now I need 2x, 2y and 2z done with the fancy low-noise resistors), so all the gains match between the 2 sets of channels.

I'm leaving the new Guralp plugged in so we can see how it behaves for the next couple days, until I take out the breakout box for stuffing.

  11295   Sat May 16 21:40:29 2015 ranaUpdatePEMGuralp maintenance

Tried swapping cables at the Guralp interface box side. It seems that all of our seismic signal problems have to do with the GUR2 cable being flaky (not surprising since it looks like it was patched with Orange Electrical tape!! rather than proper mechanical strain relief).

After swapping the cables today, the GUR2 DAQ channels all look fine: i.e. GUR1 (the one at the Y end) is fine, as is its cable and the GUR2 analog channels inside the interface box.

OTOH, the GUR1 DAQ channels (which have GUR2 (EX) connected into it) are too small by a factor of ~1000. Seems like that end of the cable will need to be remade. Luckily Jenne is still around this week and can point us to the pinout / instructions. Looks like there could be some shorting inside the backshell, so I've left it disconnected rather than risk damaging the seismometer. We should get a GUR1 style backshell to remake this cable. It might also be possible that the end at the seismometer is bad - Steve was supposed to swap the screws on the granite-aluminum plate on Thursday; I'll double check.

Attachment 1: GurPost_150516.png
GurPost_150516.png
  9154   Sun Sep 22 23:04:52 2013 ranaUpdatePEMGuralp needs recentering

 After seeing all of these spikes in the BLRMS at high frequency for awhile, I power cycled the Guralp interface box (@ 10:21 PM) to see if it would randomly recenter in a different place and stop glitching.

It did - needs to be better centered (using the paddle). Plot shows how the Z channel gets better after power cycle.

Attachment 1: seis.pdf
seis.pdf
  6693   Sat May 26 23:57:11 2012 DenUpdatePEMGuralp noise

I've looked through the Guralp manual to figure out what noise do they declare. They present it in acceleration units in dB relative to 1 m2 / s4 / Hz. I've converted my measurements to this units and got

noises.png

They declare much better noise. May be linoleum makes an effort. Do we have any isolation boxes?

  6697   Tue May 29 00:39:52 2012 DenUpdatePEMGuralp noise

I've connected Guralp output to the ADC without readout box. I've got the same noise at low frequencies and even worse noise at high frequencies. However, readout box was still used as DC supply and the signal was read from INPUT test points. I'll do the same experiment without touching readout box at all.

in_out.png

  6712   Tue May 29 22:48:37 2012 DenUpdatePEMGuralp noise

I've checked whether the Guralp noise that we see comes not from seismometer but from ADC or readout box. I did 2 separate measurements . First, I've split 1 signal from Guralp into 2 before the input to AA board and subtracted one from another using Wiener filter. Second, I've connected inputs of channels 1 and 4 of the seismometer readout box and put the signal from seismometer to channel 1.

split_noises.png

The plot shows that ADC and readout box do not contribute too much to the Guralp noise.

  6691   Sat May 26 15:59:19 2012 DenUpdateIOOGuralp noise is high

As I've mentioned in yesterday's elog MC mirrors start to move in a synchronistic manner. I've plotted DELTA_GUR = GUR1_X - alpha * GUR2_X, where alpha = const to make the transfer functions SEISMOMETER -> ADC equal for each channel. I've noticed that DELTA_GUR decreases below 10 Hz compared to GUR1_X as theoretically predicted. But starting from 1 Hz DELTA_GUR starts to increase. I decided that this is Guralp noise floor. Today I checked this, this is indeed the case.

In the frequency range 0.01 - 1.5 Hz Gur noise is comparable to the signal DELTA_GUR. For that reason we see low coherence between MC_F and GUR1_X in this frequency range. 

gur_noise.png    MCF_GUR.png

Guralp noise floor was determined by placing 2 seimometers close to each other and subtracting by Wiener filtering.

DSC_4306.JPG

Conclusion: To filter seismic noise out of MC_F we need more sensitive seimometeres.

 

  1153   Fri Nov 21 17:27:47 2008 JenneUpdatePEMGuralp noise measurement
Here is the data from the Guralp Seismometer for the past day or so, before I fixed the VERT-1 channel. The NS and EW show what's going on in the world, and VERT is measuring essentially the noise of the box, through the ADC, in counts.
Attachment 1: guralp_vert_shorted.jpg
guralp_vert_shorted.jpg
  1154   Fri Nov 21 19:47:26 2008 ranaUpdatePEMGuralp noise measurement
and here's the spectra with them connected - from the coherences, it looks like it needs to be rotated by 90 deg.

I'll next rename the channels to fix this so that we get good seismic data over the weekend with the MC.
Attachment 1: a.png
a.png
  1156   Fri Nov 21 21:20:24 2008 ranaUpdatePEMGuralp noise measurement
This is the spectra and time series of the Guralp channels along with the Ranger (MC2). Looks like we could reduce the gain
on the ranger. The Guralp channels run into ADC noise around 40 Hz (which is OK). We'll have to look at the weekday trends
to see if they saturate.
Attachment 1: a.png
a.png
  3267   Thu Jul 22 13:44:47 2010 JennaUpdatePEMGuralp seismometer

One of the Guralps [Gur2] has been taken to the atf gyro lab, along with the breakout box.

 

Edit by Jenne:  This means that we have no working seismometers in the 40m lab right now, so don't worry if you're looking for seismo data and you can't find any.  The 6 accelerometers should all still be up and running.

  1152   Fri Nov 21 16:52:48 2008 JenneUpdatePEMGuralp seismometer's Channel Problems are solved
PROBLEM noticed earlier this week: It looked like one of the seismometer channels (VERT-1) wasn't working, no matter how I put which channel into which input of the PEM ADCU. Watching the channel on Dataviewer, it looked like the ADC was measuring VERT-1 to be zero (actually measuring zero, not digital noise-type zero). I had checked the ADC by putting in a sine wave with a function generator, and saw on Dataviewer the wave I expected, so I knew that I had the correct channel, and that the channel was good.

SOLUTION: This afternoon I took the box out of the rack and opened it up. As soon as I opened it, I saw that I had left something inside the box which was causing the problem. Back when we were measuring the noise of the box, to ensure that it is lower than the ADC's noise, Rana and I had shorted the test points on the input of the VERT-1 channel with a little piece of wire. It turns out that I had closed up the box without remembering to remove the wire.

CONCLUSION of the story: I took out the piece of wire, and now all three seismometer channels (VERT-1, N/S-1, E/W-1) all work, and all detect me jumping around near the BSC. Since the seismometer breakout box reads a differential measurement, and since the input test points were connected, it was indeed measuring zero. Zero equals zero is all well and good, but it's even better now that it's measuring actual seismic motion.
  8925   Thu Jul 25 14:45:06 2013 ranaUpdatePEMGuralp specgram with ligoDV and NDS2

 Once you install a matlab newer than 2012a, you can install ligoDV as a matlab app and get the NDS2 client software for free. So you can easily get the 40m data from the outside world now and do the analysis on your own computer rather than login through nodus.

Attachment 1: a.pdf
a.pdf
  3147   Wed Jun 30 14:38:04 2010 JenneUpdatePEMGuralp terminator is switched

I moved the Guralp box's input terminator from Gur1 to Gur2 a minute or so ago to check the other channels.

  12046   Thu Mar 24 08:20:52 2016 SteveUpdatePEMGuralp-A calibration sheet

Calibration Data

All Guralp instruments and digitisers are provided with calibration documentation. Should you require a copy of calibration information for any product, email caldoc@guralp.com with the serial number of the product in the subject field and calibration information will be sent to you through email.

See data in the 40m wiki

 

  2674   Mon Mar 15 16:39:36 2010 steveUpdatePEMGuralp2 centered

Quote:

Untitled.png

 

Guralp 2 centered.The mass position offsets are: E-W 0.05V, N-S 0V, Z 0.4V

Guralp 1: E-W -0.1V, N-S -0.25V, Z 0V measured, not adjusted

The GUR2_X channel has an offset. See plot below when seismometers are disconnected. This offset has to be removed.

NOTE: this huddle is on bad-soft ground-lenoleum tile from prehistoric Flintstone age

 

Attachment 1: grlp2ffst.jpg
grlp2ffst.jpg
  2685   Fri Mar 19 18:00:14 2010 jenneUpdatePEMGuralp2 centered again

[Jenne, Sanjit]

It looks like Steve used a GND-12V supply to power the Guralp through the little breakout box (the box is for checking the centering of the mass).  This is BAD.  The Guralps want +/- 12V.

We centered all of the channels on Gur2, and checked the channels on Gur1, so we'll see how they're feeling after a while.

  2686   Fri Mar 19 21:15:33 2010 ranaUpdatePEMGuralp2 centered again

This trend of the last 200 days shows that GUR2 has been bad forever...until now anyways.

Attachment 1: Untitled.png
Untitled.png
  2687   Fri Mar 19 23:03:41 2010 ranaUpdatePEMGuralp2 centered again

I went and double-checked and aligned the styrofoam cooler at ~5:00 UTC. It was fine, but we really need a better huddling box. Where's that granite anyway?

Here's the new Huddle Test output. This time I show the X-axis since there's some coherence now below 0.1 Hz.

You'll also notice that the Wiener filter is now beating the FD subtraction. This happened when I increased the # of taps to 8000. Looks like the noise keeps getting lower as I increase the number of taps, but this is really a kind of cheat if you think about it carefully.

Attachment 1: huddlez.png
huddlez.png
  2689   Sun Mar 21 19:25:29 2010 ranaUpdatePEMGuralp2 centered again

From this morning, now in calibrated units, and with the Güralp self noise spec from the Güralp manual.

Attachment 1: huddlez.png
huddlez.png
  2678   Thu Mar 18 08:49:51 2010 steveUpdatePEMGuralp2 centered again ?

 

Someone adjusted the Guralp2 mass position last night??

NO

Attachment 1: grlp2xadj.jpg
grlp2xadj.jpg
  8954   Thu Aug 1 16:33:39 2013 SujanUpdatePEMGuralp2 seismometer installed at North side of POX table

1)Power to the seismometers were turned down,

2)Guralp2 was moved to North side of POX table

3)Guralp2 was aligned in N-s Direction and leveled before connecting

4)Power to seismometers was turned on once Guralp2 was connected

IMG_1213.JPG

  2713   Thu Mar 25 09:07:08 2010 steveUpdatePEMGuralp2 x problem is back

Quote:

I went and double-checked and aligned the styrofoam cooler at ~5:00 UTC. It was fine, but we really need a better huddling box. Where's that granite anyway?

Here's the new Huddle Test output. This time I show the X-axis since there's some coherence now below 0.1 Hz.

You'll also notice that the Wiener filter is now beating the FD subtraction. This happened when I increased the # of taps to 8000. Looks like the noise keeps getting lower as I increase the number of taps, but this is really a kind of cheat if you think about it carefully.

 The same thing happening again.  The intermittent offset upstream of the seismometer that never got fixed.

The granite plate and ball bearings are in. I will place seismometers on it.

Attachment 1: grlp2xproblm.jpg
grlp2xproblm.jpg
  11341   Mon Jun 1 15:22:19 2015 SteveUpdatePEMGuralps X- short cable is bad

 

Quote:

Koji and Steve,

The result: bad Guralp x-arm cable.

I will swap the short cables tomorrow at the base.

 

Short 46" long cables at the base plates were swapped. Their solderings looked horrible.

This cable actually worked at 5-5-2015

Bad cable at ETMY station now.  The new cable should be a little bit longer ~52"

Attachment 1: seismGur1-2.png
seismGur1-2.png
  12044   Wed Mar 23 15:23:12 2016 SteveSummaryPEMGuralps as connected

We have one calibration sheet of GUR- B, from 26 June 2008,    model CMG-T40-0008,  sn T4157       at  ETMY  east,  interface box input 1

I'm looking for calibration paper of GUR- A,                                model CMG-T40-0053,  sn T4Q17      at ETMX   south, interface box input 2

Quote:

I measured the guralp raw outputs and the TFs using the handheld unit and an FFT analyzer.

[Setup]

The handheld unit was connected to each guralp with the same cable which is confirmed t be functional with the Yend Guralp.

The signal for Z, N, and E directions are obtained from the banana connectors on the handheld unit. Each direction has mass, low gain velocity, and high gain velocity output. The PSDs of the signals were measured with an FFT analyzer. The transfer function from the mass signal to the low/high gain signals were also measured for each direction.

The adjustment screw for the E output of the Xend does not work. I had to tilt the Xend Guralp using the leg screws to bring the E signal to zero.

[Result]

Attachment 1: Raw voltage PSD for all outputs
Attachment 2: Comparison of the low gain vel outputs

- All of the mass output show similar PSDs.
- Low gain velocity outputs shows somewhat similar levels. I still need to check if the output is really the ground velocity or not.
- High gain velocity outputs are either not high gain, broken, or not implemented.

- We need to calibrate the low gain output using signal injection, huddle test, or something else.

Attachment 3: TFs between each mass output and the low or high gain outputs

- TFs between the mass signal and the low vel signals show the similar transfer functions between the channels.
- The high gain outputs show low or no transfer function with regard to the mass signals.
 

 

Attachment 1: GUR_A.jpg
GUR_A.jpg
Attachment 2: GUR_B.jpg
GUR_B.jpg
Attachment 3: GUR_Interface_Box.jpg
GUR_Interface_Box.jpg
  12365   Wed Aug 3 14:52:37 2016 SteveSummaryPEMGuralps as connected

Guralps as connected with pictures

  3334   Fri Jul 30 17:24:22 2010 JenneUpdatePEMGuralps back in the 40m

I brought the GUR2 seismometer back from Bridge so I can get some more MC/Seismic data during the next week while we're pumped down, before we start doing things to the PSL table.  Both of the Gur Seismometers are connected back up to the breakout box as of ~3:27pm today.  Alastair still has the handheld controller thing (which I use for mass centering, on occasion), since he'll want the seismometer back in a week or two when I'm done with it.

 

Something is wrong with both X channels of the Guralps.  Alastair claimed that he and Frank didn't do anything bad when they opened up the breakout box, but I am suspicious. 

 

While I'm at it, a reminder that Jan and his SURF student Greg still have the Ranger, disassembled over in Bridge.  They made a note in their elog, but not in the 40m elog when they took it back again.

Whenever you're done with the Mode Cleaner for the next week, please make sure it is locked, nicely aligned and happy before you leave.  Also please make a note of what you're doing and when, so that I know what is good data and what is data with unusual conditions.

In other, semi-bad news (but already recovered from), when I was finishing putting the Guralp Breakout Box back in the rack, I bumped the power strip that is on the top back side of the rack, near the corner that the door opens on (not the corner the door hinges on).  I turned the power strip back on, and I think everything that is connected to it came back okay.  Anyhow, my bad. Sorry. 

  11331   Thu May 28 16:43:52 2015 SteveUpdatePEMGuralps swapped

Koji and Steve,

The result: bad Guralp x-arm cable.

I will swap the short cables tomorrow at the base.

 

Attachment 1: GursSwapped.png
GursSwapped.png
  6971   Thu Jul 12 21:17:44 2012 MashaUpdatePEMGurlap 2 Problems

I noticed on DataViewer today that GUR2 was outputting only noise (somewhere around 2 counts). Jenne suggested that GUR 2 might not be plugged in. I turned off the ADC, and tried several times to plug GUR 2 back in. I thought something might be wrong with the cable, but when I plugged the GUR1 cable into GUR2, there was still no readout (although the GUR1 cable works fine when I plug it into GUR1). Perhaps I'm just inept at plugging in GUR2, or perhaps there's another issue. Either way, I'll ask Jenne about it tomorrow and try again.

  7059   Tue Jul 31 15:33:17 2012 MashaConfigurationPEMGurlap Pin Map

I checked the connections specified in the old Gulap Pin Map and found that they do not correspond to the current values. I mapped out the current connections (in this case, the letter refers to the labeled pin on the mil/spec while the number refers to the pin on the 37 pin DSub, labeled consecutively):

A-1, B-2, C-3, D-4, E-5, F-6, G-7, H-Unused, J-8, K-unused, L-9, M-10, N -11, P-12, S-13, T-Unused, U-14, V-15, W-16, X-17, Y-18, Z-Unused, a-Unused, b-19, c-20, UnlabeledPin-Unused.

There are 20 pins in use of 26 total, which is good because that means Jenne and I can use the ~70m long 24 wire cable to make a new Gurlap 1 cable.

GurlapPinMap3.png

  11612   Thu Sep 17 16:04:09 2015 SteveUpdatePEMGurs

ETMY - Guralp (B-MIT) was covered with copper lined can yesterday afternoon. It's long cable is connected to ADC interface box input 1

The vertex Trillium was covered just ~2 days before Ignacio left.

ETMX - Guralp (A-Caltech) is not covered. The long 40m cable is disconnected at the the south end.

 

  11554   Tue Sep 1 10:36:06 2015 SteveUpdatePEMGurs swapped
Quote:

To help find out if Steve really melted the inside of our precious seismometer, lets hook it up using the handheld seismo wand and see if it produces volts when we shake the ground.

Also, please stop using names like GurA or Gur1 or GurSuzy. We have GurX and GurY because they are at those ends. Anything else is confusing.

I moved Gur A from ETMX to ETMY . Gur B at ETMY was disconnected and its cable  connected to Gur A

It seems that Gur A is alive. I will stop using A and B names after we stop swapping components.

Attachment 1: GurA@ETMY.png
GurA@ETMY.png
  2934   Fri May 14 16:19:22 2010 JenneUpdatePEMGuts of a Guralp

[Jenne, Rana]

We took apart and examined one of the Guralp seismometers this afternoon.  For the most part we think we understand how it works. The horizontal sensors are a little more confusing, since we didn't end up finding the moving masses.  The vertical sensor is a flat rectangle, hinged at one edge.  There are capacitive sensors above and below the rectangle.  The hinged end is connected to a leaf spring. 

The PCBs are packed full of old-school 80's components.  We probably need an actual schematic to figure out where the preamp circuit is, which is what we'd want to think about fitzing with, if we were to try to improve the noise of the seismometer.  For now, we put it all back together, and back out on the granite slab. 

There was a wee bit of confusion when putting the N/S marker-spikes back on as to where they should go.  The solution is that the handle of the seismometer is aligned with the North/South axis, so the spikes should be aligned with the handle.  The lid of the seismometer is uniquely aligned to the stuff inside by the ribbon cable connector, as well as the holes in the lid for accessing the centering potentiometers.  So, align the lid to the pots, and then align the spikes to the handle.

Photos are on Picasa.

  15781   Thu Jan 28 18:04:55 2021 AnchalSummaryBHDHAM-A Coil Driver measurements After modifications

I did the recommended modifications on of the boards with serial number S2100028. These included:

  • R13, R27: 160 -> 75
  • C11, C21: 470 nF -> 68nF
  • C19: 4.7 uF -> 470 nF
  • R15: 3.23 kOhm -> 1.82 kOhm

I took transfer function measurements with same method as in 40m/15774 and I'm presenting it here to ensure the modifications are correct and if I should proceed to the next board as well. I didn't have the data used to make plots in here but I think the poles and zeros have landed in the right spot. I'll wait for comments until tomorrow to proceed with changes in the other board as well. I'll do noise measurements tomorrow.

Attachment 1: D1100117_S2100027_TF.pdf
D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf
Attachment 2: AfterChanges.zip
  15782   Thu Jan 28 21:44:45 2021 gautamSummaryBHDHAM-A Coil Driver measurements After modifications

Looks fine to me visually but the verdict can only be made once the z:p locations are quantitatively confirmed, and the noise tests pass. It would be interesting to see what kind of time-domain transient (in N of force) switching on the de-whitening introduces, i guess best done interferometrically.

Quote:

I'll wait for comments until tomorrow to proceed with changes in the other board as well. I'll do noise measurements tomorrow.

  15784   Fri Jan 29 15:39:30 2021 AnchalSummaryBHDHAM-A Coil Driver measurements After modifications TF and Noise S2100027

I fitted zeros and poles in the measured transfer function of D1100687 S2100027 and got zeros at 130 Hz and 234 Hz and poles at 10Hz and 2845 Hz. These values are different from the aimed values in this doc, particularly the 234Hz zero which was aimed at 530 Hz in the doc.

I also took the noise measurement using the same method as described in 40m/15780. The noise in Acquisition mode seems to have gone up in 10 Hz - 500 Hz region compared to the measurement in 40m/15780 before the modifications.

All channels are consistent with each other.


Edit Mon Feb 1 12:24:14 2021:
Added zero model prediction after the changes. The measurements match with the predictions.


Edit Wed Feb 3 16:46:59 2021:

Added zero modeled noise in the noise spectrum curves. The acquisition mode curves are in agreement with the model. The noise in Run mode is weirdly lower than predicted by zero.

Attachment 1: D1100687_S2100027_After_Modifications_Jan28.jpg
D1100687_S2100027_After_Modifications_Jan28.jpg
Attachment 2: D1100117_S2100027_TF.pdf
D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf
Attachment 3: D1100117_S2100027_Voltage_Noise_Spectrum.pdf
D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf
Attachment 4: D1100117_S2100027_Current_Noise_Spectrum.pdf
D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf
Attachment 5: AfterChanges.zip
  15787   Tue Feb 2 11:57:46 2021 AnchalSummaryBHDHAM-A Coil Driver measurements After modifications TF and Noise S2100028

I have made the modifications on the other board D1100687 S2100028 as well. The measurements were taken as mentioned in 40m/15784. All conclusions remain the same as 40m/15784. The attached zip file contains all measurement data, before and after the modifications.


Edit Wed Feb 3 16:44:51 2021 :

Added zero modeled noise in the noise spectrum curves. The acquisition mode curves are in agreement with the model. The noise in Run mode is weirdly lower than predicted by zero.

Attachment 1: D1100687_S2100028_After_Modifications_Feb01_2021.jpg
D1100687_S2100028_After_Modifications_Feb01_2021.jpg
Attachment 2: D1100117_S2100028_TF.pdf
D1100117_S2100028_TF.pdf D1100117_S2100028_TF.pdf D1100117_S2100028_TF.pdf D1100117_S2100028_TF.pdf D1100117_S2100028_TF.pdf
Attachment 3: D1100117_S2100028_Voltage_Noise_Spectrum.pdf
D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf
Attachment 4: D1100117_S2100028_Current_Noise_Spectrum.pdf
D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf
Attachment 5: AfterChanges.zip
  15774   Wed Jan 20 18:07:09 2021 AnchalSummaryBHDHAM-A Coil Driver measurements before modifications

I have taken transfer functions and noise measurements of the two HAM-A coil driver boxes D1100687 #S2100027 and #S2100028. All transfer functions look as expected. I'm not sure about the noise measurements. If anyone sees flaw in my measurement method, please let me know. I'm not sure why in some channels I got 10Hz harmoni peaks in the noise. That was very strange. Also let me know if my current noise estimate is wrong.

Transfer Function Measurement details

  • SR785 source out was connected to the differential amplifier input of D1900068.
  • The one pair of two BNC outputs of this differential amplifier goes directly to the SR785 Input 1 A and B.
  • The DB9 output of the differential amplifier goes to the Coil Input DB9 connector J3.
  • Header W2 was shorted to provide ground to the incoming signal.
  • Header P4 was shorted to enable all the channels manually.
  • Normal operation is the Acquisition mode (Acq) while when pins of header P3 are shorted, we go into the Run mode for respective channel.
  • The “To Satellite Box” DB25 port at the read side was conencted to a DB25 breakout circuit and pins 1-9, 3-11, 5-13 and 7-15 were connected to 36 Ohm resistor to simulate Coil load.
  • The “Output Monitor” on the rear side is then connected to the test switch DB9 port on D1900068.
  • The the pair of BNCs from the test switch is connected to SR785 Input 2 A and B.
  • Measurements are taken with file D1100687_TF.yml and D1100687_TF_LF.yml.
  • A measurement of just cables without the DUT is taken as well.
  • Commands.txt list all the commands used.
  • All data is compiled and plotted in Plotting.ipynb
  • D1100117_S2100027_TF.pdf and D1100117_S2100028_TF.pdf shows all the transfer functions measured.

Spectrum Measurements

  • All channels were kept in disabled mode (Not shorting P4) to ensure their inputs are grounded on the board.
  • I ran two BNC cables with their centers connected to output monitors V2+ and V2- and one of their shields connected to board GND.
  • in SR785, A-B differential mode always runs with grounded shields mode, so effectively the board GND got grounded to SR785 GND through internal 50 Ohm resistor. But all ground loops have been evaded.
  • The two BNC cables were twisted together to minimize the area between the two center cores of the cables as that is the remaining pickoff possible in this measurement.
  • Instrument noise with cables was measured first but shorting the clips of the center cores and one of the shields of the two BNC cables together.
  • Measurements were taken with file D1100687_SP.yml and D1100687_SP_LF.yml.
  • D1100117_S2100027_Voltage_Noise_Spectrum.pdf and D1100117_S2100028_Voltage_Noise_Spectrum.pdf shows the measured voltage noise spectrum at the output monitors when loaded with 36 Ohms.
  • D1100117_S2100027_Current_Noise_Spectrum.pdf and D1100117_S2100028_Current_Noise_Spectrum.pdf shows the esitmate current noise through the coil calculated by dividing the measured voltage noise by 2436 Ohms.
Attachment 1: MeasurementData.zip
Attachment 2: D1100117_S2100027_TF.pdf
D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf D1100117_S2100027_TF.pdf
Attachment 3: D1100117_S2100028_TF.pdf
D1100117_S2100028_TF.pdf D1100117_S2100028_TF.pdf D1100117_S2100028_TF.pdf D1100117_S2100028_TF.pdf D1100117_S2100028_TF.pdf
Attachment 4: D1100117_S2100027_Voltage_Noise_Spectrum.pdf
D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf
Attachment 5: D1100117_S2100028_Voltage_Noise_Spectrum.pdf
D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf
Attachment 6: D1100117_S2100027_Current_Noise_Spectrum.pdf
D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf
Attachment 7: D1100117_S2100028_Current_Noise_Spectrum.pdf
D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf
  15780   Thu Jan 28 12:53:14 2021 AnchalSummaryBHDHAM-A Coil Driver measurements before modifications

I took some steps to reduce the coupling of 60 Hz harmonics in noise measurement. The box was transferred to the floor instead of on top of another instrument. Measurement was immediately converted into single-ended using SR560 in battery mode with a gain of 10. All of the setups was covered in aluminum foil to increase isolation.

Spectrum measurement details

 

Attachment 1: D1100117_S2100027_Current_Noise_Spectrum.pdf
D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf D1100117_S2100027_Current_Noise_Spectrum.pdf
Attachment 2: D1100117_S2100027_Voltage_Noise_Spectrum.pdf
D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf D1100117_S2100027_Voltage_Noise_Spectrum.pdf
Attachment 3: D1100117_S2100028_Current_Noise_Spectrum.pdf
D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf D1100117_S2100028_Current_Noise_Spectrum.pdf
Attachment 4: D1100117_S2100028_Voltage_Noise_Spectrum.pdf
D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf D1100117_S2100028_Voltage_Noise_Spectrum.pdf
Attachment 5: SpectrumMeasurement.zip
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