40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
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ID Date Authorup Type Category Subject
  14420   Tue Jan 29 16:12:21 2019 ChubUpdate  

The foam in the cable tray wall passage had been falling on the floor in little bite-sized pieces, so I investigated and found a fiber cable that had be chewed/clawed through.  I didn't find any droppings anywhere in the 40m, but I decided to bait an un-set trap and see if we'd find activity around it. There has been none so far.  If there is still none tomorrow, I will move the trap and keep looking for signs of rodentia.  At the moment, the trap is in a box in front of the double doors at the north end of the control room.  Next it will be place in the IFO room, up in the cable tray. 

gautam: the fiber that was damaged was the one from the LSC rack FiBox to the control room FiBox. So no DAFI action for a bit...

  14437   Wed Feb 6 10:07:23 2019 ChubUpdate pre-construction inspection

The Central Plant building will be undergoing seismic upgrades in the near future.  The adjoining north wall along the Y arm will be the first to have this work done, from inside the Central Plant.  Project manager Eugene Kim has explained the work to me and also noted our concerns.  He assured me that the seismic noise from the construction will be minimized and we will always be contacted when the heaviest construction is to be done.

Tomorrow at 11am, I will bring Mr. Kim and a few others from the construction team to look at the wall from inside the lab.  If you have any questions or concerns that you want to have addressed, please email them to me or contact Mr. Kim directly at x4860 or through email at eugene.kim@caltech.edu . 

  14572   Thu Apr 25 10:13:15 2019 ChubUpdateGeneralAir Handler Out of Commission

The air handler on the roof of the 40M that supplies the electronics shop and computer room is out of operation until next week.  Adding insult to injury, there is a strong odor of Liquid Wrench oil (a creeping oil for loosening stuck bolts that has a solvent additive) in the building.  If you don't truly need to be in the 40M, you may want to wait until the environment is back to being cool and "unscented".  On a positive note, we should have a quieter environment soon!

  14601   Fri May 10 13:00:25 2019 ChubUpdateGeneralcrane inspection complete

The 40M jib cranes all passed inspection!

Attachment 1: 20190510_110245.jpg
  14749   Thu Jul 11 13:08:36 2019 ChubSummaryCDSP2 interface board

It's nice and compact, and the cost of new 15-pin DSUB cables shouldn't be a factor here.  What does the 15p cable connect to?

  14869   Tue Sep 10 16:10:40 2019 ChubUpdate Rack Update

Still removing old cable, terminal blocks and hardware.  Once new strain reliefs and cable guides are in place, I will need to disconnect cables and reroute them.  Please let me know dates and times when that is not going to interrupt your work! 

Attachment 1: 20190910_154018.jpg
Attachment 2: 20190910_154006.jpg
  15222   Mon Feb 24 08:36:32 2020 ChubUpdateGeneralHVAC repair

The HVAC people replaced a valve and repaired the pneumatic plumbing on the roof air handler.  Temperature has been stable during the day since Thursday.  If anyone is in the control room during the evening, please make a note of the temperature.


  15304   Wed Apr 15 15:15:17 2020 ChubUpdateVACnitrogen cylinders delivered

Four nitrogen cylinders replaced the empties in the rack at the west entrance.  Additionally, Airgas will now deliver only once a week.  Let me know via email or text when the there are four empties in the rack and I'll order the next round.

  15314   Thu Apr 30 07:29:01 2020 ChubUpdateVACN2 delivered.

Hi All,

The new nitrogen cylinders were delivered to the rack at the west entrance.  We only get one Airgas delivery per week during the stay-at-home order, but so far they've not let us down.

  15416   Fri Jun 19 11:02:10 2020 ChubUpdateGeneralcustom feedthrough flanges are here!

The four 4x25DSUB and single 8x25DSUB feedthrough flanges have arrived and will be picked up from the dock and brought to the 40M lab.

  15680   Tue Nov 17 13:24:40 2020 ChubUpdateGeneralbig UPS on the way

Ordered 11/16 from CDW, on PO# S492940, the high voltage Tripp Lite SMART5000XFMRXL  for TP-1.  Should be arriving in about a week.

  15722   Thu Dec 10 11:07:24 2020 ChubUpdateVACUPS fault

Is that a fault code that you can decipher in the manual, or just a light telling you nothing but your UPS is dead?

  15723   Thu Dec 10 11:17:50 2020 ChubUpdateVACUPS fault

I can't find anything in the manual that describes the nature of the FAULT message.  In fact, it's not mentioned at all.  If the unit detects a fault at its output, I would expect a bit more information.  This unit does a programmable level of input error protection, too, usually set at 100%.  Still, there is no indication in the manual whether an input issue would be described as a fault; that usually means a short or lifted ground at the output.


Is that a fault code that you can decipher in the manual, or just a light telling you nothing but your UPS is dead?

  16058   Wed Apr 21 05:48:47 2021 ChubUpdateGeneralPSL HEPA Maintenance

Yikes!  That's ONE filter.  I'll get another from storage.

  16074   Thu Apr 22 14:41:55 2021 ChubUpdatePSLNew HEPA speed control

When adjusting the blower speed, give the blower at least 30 seconds to speed up or slow down to the set speed.  The flywheel effect of the big motor armature and blower mass requires time to follow the control current.  Note the taller Flanders HEPA filters.  These and the new intake filters should keep the PSL air clean for a long time!


The new HEPA speed controllers are attached at the middle of the HEPA unit (not at the edge of the unit)... (Attachment 1)
You still need a step./stool to touch the knob and need a ladder for a more precise setting.

We still don't know the optimal speed of the nominal IFO operation. For now, the HEPAs are running at the max speed (Attachment 2).
Once we know the optimal setting, we mark the knobs so that we can see them only with the step.


Attachment 1: 40M_PSL_HEPA.jpg
  16121   Wed May 5 13:05:07 2021 ChubUpdateGeneralchassis delivery from De Leone

Assembled chassis from De Leone placed in the 40 Meter Lab, along the west wall and under the display pedestal table.  The leftover parts are in smaller Really Useful boxes, also on the parts pile along the west wall.

Attachment 1: de_leone_del_5-5-21.jpg
  16155   Mon May 24 08:38:26 2021 ChubUpdateElectronics18-bit AI, 16-bit AI and 16-bit AA

- High priority units: 2x 18AI / 1x 16AI / 3x 16AA

All six are reworked and on the electronics workbench. The rest should be ready by the end of the week.


  16160   Tue May 25 17:08:17 2021 ChubUpdateElectronicschassis rework complete!

All remaining chasses have been reworked and placed on the floor along the west wall in Room 104. 

Attachment 1: 40M_chassis_reworked_5-25-21.jpg
  16472   Wed Nov 17 07:32:48 2021 ChubUpdateGeneralwire clamp plate mod

This will be difficult to modify with the magnets and dumbells in place.  Even if someone CAN clamp this piece into an endmill machine with the magnets/dumbells in place, the vibration of the cutting operation may be enough to break them off.

  16513   Thu Dec 16 15:04:12 2021 ChubUpdateElectronicsITMX feedthroughs and in-vac cables installed

The ITMX 10" flange with four DSUB-25 feedthroughs has been install with the cables connected at the in-vac side.  See photo; as requested, LO1-1 and LO1-2 are connected to the top row of feedthroughs from left to right respectively and the opposite ends of the cables placed left to right on the laser table.  PR2-1 and PR2-2 are connected to the lower row of feedthroughs from left to right respectively, with the opposite ends placed on the surface below the laser from left to right.  This seemed the easiest way to keep the cable orientation clear.

Attachment 1: ITMX_feedthrough_install_12-16-21.jpg
  16644   Thu Feb 3 14:47:12 2022 ChubUpdateElectronicsnew UPS in place

Received the new 1100VA APC UPS today and placed it at the bottom of the valve rack.  I'd connected the battery and plugged the unit into the AC outlet, but did not turn it on due to the power outage this weekend.

  16646   Fri Feb 4 10:04:47 2022 ChubUpdateGeneraldish soap and clean scrub sponges!

Bought dish soap and scrub sponges today and placed them under the sink with the other dish supplies.

Attachment 1: 40m_supplies.jpg
  16921   Wed Jun 15 17:12:39 2022 CiciSummaryGeneralPreparation for AUX Loop Characterization

[Deeksha, Cici]

We went to the end Xarm station and looked at the green laser setup and electronics. We fiddled with the SR-785 and experimented with low-pass filters, and will be exploring the Python script tomorrow.

  16926   Thu Jun 16 19:49:48 2022 CiciUpdateGeneralUsing the SR785

[Deeksha, Cici]

We used a python script to collect data from the SR785 remotely. The SR785 is now connected to the wifi network via Ethernet port 7.

  16933   Tue Jun 21 14:59:22 2022 CiciSummaryGeneralAUX Transfer Function Loop Exploration

[Deeksha, Cici]

We learned about the auxillary laser control loop, and then went into the lab to identify the components and cables represented by our transfer functions. We connected to the SR785 inside the lab so that we can use it to insert noise next time, and measure the output in various parts of the control loop.

  16950   Mon Jun 27 13:25:50 2022 CiciUpdateGeneralCharacterizing the Transfer Loop

[Deeksha, Cici]

We first took data of a simple low pass filter, and attempted to perform a fit to both the magnitude and phase in order to find the Z of the components. Once we felt confident in our ability to measure tranfer functions, we took data and plotted the transfer function of the existing control loop of the AUX laser. What we found generally followed the trend of, but was lower than, 10^4/f, which is what we hoped to match, and also had a strange unexplained notch ~1.3 kHz. The magnitude and phase data both got worse after around 40-50 kHz, which we believe is because the laser came out of lock near the end of the run. 


[Attachment 2 and 3] are the frequency response of the low pass filter, curves fitted using least squares in python.

[Attachment 1 and 4] is the same measurement of OLTF of the actual AUX circuit, and the control diagram pointing out the location of excitation and test point.

Attachment 1: TF_measurement_b.png
Attachment 2: transfer_function_mag_fit.png
Attachment 3: transfer_function_phase_fit.png
Attachment 4: control_flow.png
  16955   Tue Jun 28 16:26:58 2022 CiciSummaryGeneralVector fitting open loop transfer function/Audio cancellation of optical table enclosure

[Deeksha, Cici]

We attempted to use vectfit to fit our earlier transfer function data, and were generally unsuccessful (see vectfit_firstattempt.png), but are much closer to understanding vectfit than before. Couple of problems to address - finding the right set of initial poles to start with has been very hard, and also however vectfit is plotting the phase data is unwrapping it, which makes it generally unreadable. Still working on how to mess with the vectfit automatically-generated plots. In general, our data is very messy (this is old data of the transfer function from last week), so we took more data today to see if our coherence was the problem (see TFSR785_28-06-2022_161937.pdf). As is visible from the graph, our coherence is terrible, and above 1kHz is almost entirely below 0.5 (or 0.2) on both channels. Figuring out why this is and fixing it is our first priority.

In the process of taking new data, we also found out that the optical table enclosure at the end of the X-arm does a decent job of sound isolation (see enclosure_open.mp4 and enclosure_closed.mp4). The clicking from the shutter is visible on a spectrogram at high frequencies when the enclosure is open, but not when it is closed. We also discovered that the script to toggle the shutter can run indefinitely, which can break the shutter, so we need to fix that problem!

Attachment 1: vectfit_firstattempt.png
Attachment 2: TFSR785_28-06-2022_161937.pdf
Attachment 3: enclosure_open.MP4
Attachment 4: enclosure_closed.MP4
  17051   Mon Aug 1 17:19:39 2022 CiciSummaryGeneralRPitaya Data on Jupyter Notebook

Have successfully plotted data from the Red Pitaya on Jupyter Notebook! Have lost years of my life fighting with PyQt. Thanks to Deeksha for heavy contribution. Next task is to get actually good data (seeing mostly noise right now and haven't figured out how to change my input settings) and then to go to set up the RPi in the lab.

  17070   Wed Aug 10 15:33:59 2022 CiciUpdateGeneralWorking Red Pitaya VNA

TL;DR: I am now able to inject a swept sine and measure a transfer function with python on my Red Pitaya! Attached is a Bode plot for a swept sine from 1 - 30 MHz, going through a band pass filter of 9.5 - 11.5 MHz.


  • Spent too long trying to get pyRPL to work, do not recommend. The code on their website has a lot of problems (like syntax-error level problems), and is ultimately designed to open up and start a GUI, which is not what I want even if it did work.
  • Found some code on the git repository of someone at Delft University of Technology, worked better but still not great (oscilloscope/spectrum analyzer functions were alright, but couldn't successfully run a VNA with it, and overcomplicated). Helped me figure out appropriate decimation factors. Realized it was not using the FPGA to get TF data but instead just collecting a lot of time trace data and then taking an FFT in the code to get the TF, which wasn't ideal.
  • Eventually switched to using the Red Pitaya SCPI server to talk to the Red Pitaya myself, successful! I inject a swept sine with a for loop that just cycles through frequencies and takes the transfer function at each one.
    • Was originally getting the transfer function by using scipy.signal.csd() and scipy.signal.welch() to get Pxy and Pxx and dividing, and then just finding the closest point in the frequency spectrum to the frequency I was inserting.
    • Switched to doing IQ demodulation myself: where x(t) is the measurement before the band pass filter and y(t) is the measurement after, taking the mean of (x(t) * cos(2pi*freq)) = a1, mean(x*sin()) = a2, mean(y*cos()) = b1, mean(y*sin()) = b2, and then TF(freq) = (b1 + i b2)/(a1 + i a2).
    • Unfortunately still taking time trace data and then calculating the TF instead of using the FPGA, but I have not found anything online indicating that people are able to get VNA capabilities on the Red Pitaya without collecting and sending all the time trace data... I'm still not sure if that's actually a Red Pitaya capability yet.


To do:

  • Will go take measurements of the AUX laser loop with the RPi! Have a good diagram of when I did it with the SR785 so it shouldn't be too hard hopefully.
  • Figure out how to get coherence data!!
  • Figure out how to get the RPi on the wifi. Right now I'm just plugging the RPi into my computer. Paco and I were working on this before and had trouble finding old passwords... Hopefully will not be too much of a roadblock.
Attachment 1: rpi_vna_test.pdf
  17076   Thu Aug 11 17:15:33 2022 CiciUpdateGeneralMeasuring AUX Laser UGF with Red Pitaya

TL;DR: Have successfully measured the UGF of the AUX laser on my Red Pitaya! Attached is one of my data runs (pdf + txt file). 


  • Figured out how to get a rudimentary coherence (use scipy.signal.coherence to get Cxy = abs(Pxy)**2/(Pxx*Pyy), then find what point is the closest to the frequency I'm inserting on that iteration of the swept sine and get the coherence closest to that). Not precisely the coherence at the frequency I'm inserting though, so not perfect... more of a lower bound of coherence.
  • Figured out how to get the UGF from the data automatically (no error propagation yet... necessary next step)
  • Put my red pitaya in the X-arm AUX laser control electronics (thank you to Anchal for help figuring out where to put it and locking the x-arm.) Counts dropped from 4500 to 1900 with the x-arm locked, so 58% mode matching. I lose lock at an amplitude >0.05 or so.
  • Wrote a little script to take data and return a time-stamped text file with all the parameters saved and a time-stamped pdf of the TF magnitude, UGF, phase, and coherence, so should be easy to take more data next time!


  • need to take more accurate coherence data
  • need to propagate uncertainty on UGF (probably high...)
  • take more data with higher coherence (the file attached doesn't have great coherence and even that was one of my better runs, will probably increase averaging since increasing amplitude was a problem)
Attachment 1: rpi_OLG_2022_08_11_16_51_53.pdf
Attachment 2: rpi_OLG_2022_08_11_16_51_53.txt
# frequency start: 500.0
# frequency stop: 50000.0
# samples: 50
# amplitude: 0.01
# cycles: 500
# max fs: 125000000.0
# N: 16384UGF: 9264.899326705621
# Frequency[Hz] Magnitude[V/V] Phase[rad] Coherence
4.999999999999999432e+02 5.216612299292965105e+01 -7.738468629291910261e-01 7.660920305860696722e-02
5.492705709937790743e+02 3.622076363933444298e+01 -5.897393740774580229e-01 3.183076012979469405e-01
... 49 more lines ...
  17087   Wed Aug 17 10:27:49 2022 CiciUpdateGeneralLocking X-arm AUX laser

TL;DR: Got the x-arm aux laser locked again and took more data - my fit on my transfer functions need improvement and my new method for finding coherence doesn't work so I went back to the first way! See attached file for an example of data runs with poor fits. First one has the questionable coherence data, second one has more logical coherence. (ignore the dashed lines.)


  • The aux laser on the x-arm was still off after the power shutdown, so Paco and I turned it back on, and realigned the oplev of the ETMX - initial position was P = -0.0420, Y = -5.5391.
  • Locked the x-arm and took another few runs - was calculating coherence by I/Q demodulation of the buffers and then recombining the I/Q factors and then taking scipy.signal.coherence(), but for some reason this was giving me coherence values exclusively above 0.99, which seemed suspicious. When I calculated it the way I had before, by just taking s.s.coherence() of the buffers, I got a coherence around 1 except for in noisy areas of the data where it dropped more significantly, and seemed to be more correlated to the data. So I'll go back to using that way.
  • I also think my fits are not great - my standard error of the fits (calculated using the coherence as weight, see Table 9.6 of Random Data by Piersol and Bendat for the formula I'm using) are enormous. Now that I have a good idea that the UGF is between 1 - 15 kHz, I'm going to restrict my frequency band and try to fit just around where the UGF would be. 


To do:

  • Reduce frequency band and take more data
  • Get fit with better standard error, use that error to calculate the uncertainty in the UGF!
Attachment 1: rpi_OLG_2022_08_16_17_00_41.pdf
Attachment 2: rpi_OLG_2022_08_16_17_01_21.pdf
  17090   Thu Aug 18 16:35:29 2022 CiciUpdateGeneralUGF linked to optical gain!

TL;DR: When the laser has good lock, the OLTF moves up and the UGF moves over!


Figured out with Paco yesterday that when the laser is locked but kind of weakly (mirrors on the optical table sliiightly out of alignment, for example), we would get a UGF around 5 kHz, but when we had a very strong lock (adjusting the mirrors until the spot was brightest) we would get a UGF around 13-17 kHz. Attached are some plots of us going back and forth (you can kind of tell from the coherence/error that the one with the lower UGF is more weakly locked, too). Error on the plots is propagated using the coherence data (see Bendat and Piersol, Random Data, Table 9.6 for the formula). 


Want to take data next week to quantitatively compare optical gain to UGF!

Attachment 1: rpi_OLG_2022_08_17_18_03_52.pdf
Attachment 2: rpi_OLG_2022_08_17_18_00_50.pdf
  17101   Wed Aug 24 10:49:43 2022 CiciUpdateGeneralMeasuring DFD output/X-arm laser PZT TF with Moku

We measured the TF of the X-arm laser PZT using the Moku so we can begin fitting to that data and hopefully creating a digital filter to cancel out PZT resonances. 


We calculated the DFD calibration (V/Hz) using:

Vrf = 0.158 mV (-6 dBm), Km = 1 (K_phi = Km*Vrf), cable length = 45m,  Tau = cable length/(0.67*3*10^8 m/s) ~ 220 ns. 

We've taken some preliminary data and can see the resonances around 200-300 kHz.


Next steps are taking more data around the resonances specifically, calibrating the data using the DFD calibration we calculated, and adjusting parameters in our model so we can model the TF.


Attachment 1: AUX_PZT_Actuator_nofit.pdf
  17103   Wed Aug 24 16:37:52 2022 CiciUpdateGeneralMore DFD/AUX PZT resonance measurements

Some more measurements of the PZT resonances (now zoomed in!) I'm adjusting parameters on our model to try and fit to it by hand a bit, definitely still needs improvements but not bad for a 2-pole 2-zero fit for now. I don't have a way to get coherence data from the moku yet but I've got a variety of measurements and will hopefully use the standard deviation to try and find a good error prediction...


Attachment 1: AUX_PZT_Actuator_narrow_fit.pdf
  17106   Thu Aug 25 16:39:31 2022 CiciUpdateGeneralI have learned the absolute basics of github

I have now added code/data to my github repository. (it's the little victories)

  17107   Fri Aug 26 12:46:07 2022 CiciUpdateGeneralProgress on fitting PZT resonances

Here is an update of how fitting the resonances is going - I've been modifying parameters by hand and seeing the effect on the fit. Still a work in progress. Magnitude is fitting pretty well, phase is very confusing. Attempted vectfit again but I can't constrain the number of poles and zeros with the code I have and I still get a nonsensical output with 20 poles and 20 zeros. Here is a plot with my fit so far, and a zip file with my moku data of the resonances and the code I'm using to plot.

Attachment 1: PZT_fit.zip
Attachment 2: AUX_PZT_Actuator_narrow_fit_1.pdf
  17112   Mon Aug 29 18:25:12 2022 CiciUpdateGeneralTaking finer measurements of the actuator transfer function

Took finer measurements of the x-arm aux laser actuator tranfer function (10 kHz - 1 MHz, 1024 pts/decade) using the Moku.


I took finer measurements using the moku by splitting the measurement into 4 sections (10 - 32 (~10^4.5) kHz, 32 - 100 kHz, 100 - 320 kHz, 320 - 1000 kHz) and then grouping them together. I took 25 measurements of each ( + a bonus in case my counting was off), plotted them in the attached notebook, and calculated/plotted the standard deviation of the magnitude (normalized for DC offset). Could not upload to the ELOG as .pdf, but the pdf's are in the .zip file.


Next steps are to do the same stdev calculation for phase, which shouldn't take long, and to use the vectfit of this better data to create a PZT inversion filter.

Attachment 1: PZT_TF_fine.png
Attachment 2: PZT_TF_fine_mag_stdev.png
Attachment 3: ATF_fine.zip
  16993   Tue Jul 12 18:35:31 2022 Cici HannaSummaryGeneralFinding Zeros/Poles With Vectfit

Am still working on using vectfit to find my zeros/poles of a transfer function - now have a more specific project in mind, which is to have a Red Pitaya use the zero/pole data of the transfer function to find the UGF, so we can check what the UGF is at any given time and plot it as a function of time to see if it drifts (hopefully it doesn't). Wrestled with vectfit more on matlab, found out I was converting from dB's incorrectly (should be 10^(dB/20)....) Intend to read a bit of a book by Bendat and Piersol to learn a bit more about how I should be weighting my vectfit. May also check out an algorithm called AAA for fitting instead.

  17006   Fri Jul 15 16:20:16 2022 Cici HannaUpdateGeneralFinding UGF

I have temporarily abandoned vectfit and aaa since I've been pretty unsuccessful with them and I don't need poles/zeroes to find the unity gain frequency. Instead I'm just fitting the transfer function linearly (on a log-log scale). I've found the UGF at about 5.5 kHz right now, using old data - next step is to get the Red Pitaya working so I can take data with that. Also need to move this code from matlab to python. Uncertainty's propagated using the 95% confidence bounds given by the fit, using curvefit - so just from the standard error, and all points are weighted equally. Ideally would like to propagate uncertainty accounting for the coherence data too, but haven't figured out how to do that correctly yet.


[UPDATE 7/22/2022: added raw data files]

Attachment 1: UGF_4042.png
Attachment 2: UGF_5650.png
Attachment 3: TFSR785_29-06-2022_114042.txt
# SR785 Measurement - Timestamp: Jun 29 2022 - 11:40:42
# Parameter File: TFSR785template.yml
#---------- Measurement Setup ------------
# Start frequency (Hz) = 100000.000000
# Stop frequency (Hz) = 100.000000
# Number of frequency points = 30
# Excitation amplitude (mV) = 10.000000
# Settling cycles = 5
# Integration cycles = 100
#---------- Measurement Parameters ----------
... 52 more lines ...
Attachment 4: TFSR785_29-06-2022_115650.txt
# SR785 Measurement - Timestamp: Jun 29 2022 - 11:56:50
# Parameter File: TFSR785template.yml
#---------- Measurement Setup ------------
# Start frequency (Hz) = 100000.000000
# Stop frequency (Hz) = 2000.000000
# Number of frequency points = 300
# Excitation amplitude (mV) = 5.000000
# Settling cycles = 5
# Integration cycles = 200
#---------- Measurement Parameters ----------
... 322 more lines ...
  1692   Tue Jun 23 23:14:36 2009 ClaraConfigurationPEMAccelerometers relocated

Both accelerometers have been moved in an attempt to optimize their positions. The MC1 accelerometer was moved from one green bar to the other (I don't know what to call them) at the base of the MC1 and MC3 chambers. That area is pretty tight, as there is an optical table right there, and I did my best to be careful, but if you suspect something has been knocked loose, you might check in that area. The MC2 accelerometer was moved from the horizontal bar down to the metal table on which the MC2 chamber rests.

  1696   Wed Jun 24 12:04:00 2009 ClaraUpdatePEMaccelerometer clarification

When I said "MC1/MC2 accelerometers," I meant the entire three-axis accelerometer set at each point.

  1698   Wed Jun 24 12:09:24 2009 ClaraUpdatePEMWeek 1(ish)

I spent the week reading up on filter algorithm theory, particularly Wiener filtering. I have also learned how to get data from specific channels at specific times, and I've been getting myself acquainted with Matlab (which I have not previously used). Finally, I started messing around with the positioning of the accelerometers and seismometers in order to try to find the setup that yields the best filtration.

  1703   Thu Jun 25 21:00:30 2009 ClaraUpdatePEMMC1 Accelerator set moved again; new XLR cables

I moved the MC1 set of accelerators. Might have bumped things. If things aren't working, look around the MC1 chamber.

Also, I constructed two new XLR cables, but have not tested them yet.

  1704   Fri Jun 26 15:22:28 2009 ClaraUpdatePEMXLR cables tested and labeled

We now have two 80-foot, female-to-female XLR cables for our pretty new microphones, one yellow and one purple. They have been tested and appropriately labeled.

Also, here is a very helpful pdf for how to properly attach the XLR connectors to a raw quad cable, as well as one for how to put the actual connectors together (ignore the cable instructions on the connector page... the cable depicted is not a quad cable).



Attachment 1: NC3FXX-EMC.pdf
Attachment 2: Cat11_p35.pdf
  1707   Sat Jun 27 02:48:09 2009 ClaraUpdatePEMI moved accelerometers and made some pretty pictures

I have been working on finding the best spots to put the accelerometer sets in order to best subtract out noise (seismometers next!). Here is a plot of what I've done so far:


All of these were 80-minute samples. The dashed line is unfiltered, solid line filtered. So, Setup #1 looks the best so far, but I didn't leave it there very long, so perhaps it was just a really awesome 80 minutes. I've put the accelerometers back in the Setup #1 position to make sure that it is really better.

And, in case you can't intuitively figure out what configuration the accelerometers are in by such descriptive names, here are some helpful pictures. I didn't know about the digital cameras at first, so these are actually sketches from my notebook, which I helpfully labeled with the setup numbers, color-coded to match the graph above! Also, there are some real-life photographs of the current arrangement (Setup #1' if you forgot).




Doesn't this one look kind of Quentin Blake-esque? (He illustrated for Roald Dahl.)


This is the MC1 set.


Guess which one this is!

  1708   Sat Jun 27 03:16:16 2009 ClaraUpdatePEMExciting microphone things!

So, I'm double-posting, but I figured the last post was long enough as it was, and this is about something different. After double and triple checking the XLR cables, I hooked up the microphone setup (mic---preamp---output) to the oscilloscope to figure out what kind of voltage would register with loud noises. So, I clapped and shouted and forgot to warn the other people in the lab what I was doing (sorry guys) and discovered that, even on the lowest gain setting, my loud noises were generation 2-3 times as much voltage as the ADC can handle (2V). And, since our XLR cables are so freaking long, we probably want to go for a higher gain, which puts us at something like 20 times too much voltage. I doubt this is really necessary, but it's late (early) and I got camera-happy, so I'm going to share anyway:


So, to deal with this issue, I made some nifty voltage dividers. Hopefully they are small enough to fit side-by-side in the ports without needing extra cableage. Anyway, they should prevent the voltage from getting larger than 2V at the output even if the mic setup is producing 50V. Seeing as my screaming as loud as I could about 2mm away from the mic at full gain could only produce 45V, I think this should be pretty safe. I put the ADC in parallel with a 25.5 kOhm resistor, which should have a noise like 10^-8 V/rHz. This is a lot smaller than 1 uV/rHz (the noise in the ADC, if I understood Rana's explanation correctly), so the voltage dividers should pose a noise issue. Now for pictures.


I opened one so you can see its innards.


In case the diagram on the box was too small to decipher...

And finally, I came up with a name scheme for the mics and pre-amps. We now have two Bluebird (bacteriophage) mics named Bonnie and Butch Cassidy. Their preamps are, naturally, Clyde and The Sundance Kid. Sadly, no photos. I know it's disappointing. Also, before anyone gives me crap for putting the labels on the mics upside-down, they are meant to be hung or mounted from high things, and the location (and stiffness) of the cable prevents us from simply standing them up. So they will more than likely be in some kind of upsidedownish position.

  1713   Thu Jul 2 05:27:12 2009 ClaraUpdatePEMVoltage Divider Oops

I tested the voltage dividers and was getting up to about 3V. I retested the mic w/o the voltage divider in place, and, lo and behold, I was able to generate about 70-75V (previously, I maxed out at 45V). I'm not 100% sure why this was, but it occurs to me that, before, the sounds I was generating were short in duration (loud claps, short yelps). This time, I tried yelling continuously into the microphone. So, probably, I simply wasn't seeing the real peak before on the scope because it was too short to pick up. I have corrected the voltage dividers (by replacing the 25.5 kOhm resistors, which were in parallel with the ADC, with 10 kOhm resistors, taking the voltage ratio to ~60:1) and tested them. I haven't been able to generate more than 1500 mV, so I think they are safe. (It's possible we would have been fine with the old setup, since I think it would be hard to get any noises as loud as I was making, but better safe than sorry, right?)

I'm attaching a diagram of the new-and-improved voltage dividers.


  1714   Thu Jul 2 06:31:35 2009 ClaraUpdatePEMFirst mic in place and connected

I clamped Bonnie (microphone) to the top of a chamber near the vertex of the arms and placed Clyde (pre-amp) on the table right below (see picture). The cable was laid and Bonnie and Clyde are plugged into port #13 on the ADC. The second cable was plugged into port #14, but it is not connected to anything. I placed the looped up cable on top of the cabinet holding the ADC.

Note: the angle in the photograph is such that we are looking along the y-arm.

Attachment 1: bonnieandclyde.JPG
  1715   Thu Jul 2 16:45:06 2009 ClaraUpdatePEMBonnie and Clyde are officially in operation! (Butch Cassidy and the Sundance Kid are in temp position)

I hooked up Bonnie and Clyde last night and tested it today. First I tried some loud noises to make sure I could identify them on the readout. Then, Steve suggested I try to look for some periodic stuff. I set up Butch Cassidy and the Sundance Kid on the cabinets by the MC2 optic. Now for graphs!



I tapped on the microphone a few times. I also yelled a bit, but this is sampling by seconds, so perhaps they got overwhelmed by the tapping.


This time I tried some more isolated yells. I started with a tap so I'd be sure to be able to recognize what happened. Apparently, not so necessary.


Here, it looks like a pretty strong periodic pattern on the second mic (Butch Cassidy). I replaced the lines with dashed ones where the pattern was a little less clear. Possibility interference from something. Mic1 (Bonnie) seems to show a pretty regular beat pattern, which seems reasonable, as it isn't particularly close to any one instrument fan.


So, anyway. I thought those were neat. And that I wanted to share.


  1718   Tue Jul 7 16:06:59 2009 ClaraUpdateComputer Scripts / ProgramsDTT synchronization errors, help would be appreciated

I am attempting to use the DTT program to look at the coherence of the individual accelerometer signals with the MC_L signal. Rana suggested that I might break up the XYZ configuration, so i wanted to see how the coherence changed when I moved things around over the past couple of weeks, but I keep getting a synchronization error every time I try to set the start time to more than about 3 days ago. I tried restarting the program and checking the "reconnect" option in the "Input" tab, neither of which made any kind of difference. I can access this data with no problem from the Data Viewer and the Matlab scripts, so I'm not really sure what is happening. Help?

EDIT: Problem solved - Full data was not stored for the time I needed to access it for DTT.

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