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 Author Type Category Subjectup
  12841   Tue Feb 21 10:08:35 2017 steveUpdatePEMnoisy morning

Our new janitor Francisco is started working in IFO room today.


The MET#1 particle counter was moved from CES wall at ITMX to PSL enclousure south west corner at 11am.

The HEPA filter speed at the Variac was turned down to 20V from 40

This counter pumps air for 1 minute in every 20 minutes. Soft foam in bags used to minimize this shaking as it is clamped.


Large film crews are working just out side  the north west corner of the lab. They started around ~ 5:30am  Do not plan on working late tonight.

ETMX sus damping restored.

C1:PSL-FSS_RMTEMP, C1:PSL-PMC_PMCTRANSPD and C1:PEM-count_temp channels are not reading since Friday


Attachment 1: outside_activity.png
  11866   Wed Dec 9 11:25:55 2015 SteveUpdateVACnormal RGA scan at day 435-436

Glitches are gone. Rga scan is good


Attachment 1: glichesGone.png
Attachment 2: d436.png
  1602   Mon May 18 20:16:20 2009 ranaConfigurationVACnot it
There was essentially no change in the ETMY oplev spectrum with the cryo off!

So I went out to the ETMY OL table to see what else was going on. I found there one of
the most horrible opto-mechanical setups
I have ever seen (and remember that I have once
seen someone mount an NPRO on a cardboard box). Some bad person had mounted the ETMY OL
lens on a 12" long skinny post and extended it towards the viewport. So there was a post
holder on the table and a lens ~12" away on a rickety lever arm.

I took this lens away and the spectrum is now good. Shame on you.
CYAN -  cryo ON
BLACK - cryo OFF
BLUE -  no crappy lens + mount

This OL needs to be fixed correctly by putting in a proper lens to get a small spot on the QPD.
Attachment 1: a.png
  14301   Fri Nov 16 15:09:31 2018 SteveConfigurationVACnot venting cryo and ion pumps

Notes on the ion pumps and cryo pump:

  • Our 4 ion pumps were closed off for a lomg time. I estmated their pressure to be around ~1 Torr. After talking with Koji we decided not to vent them.

  • It'd be still useful to wire their position sensors. But make sure we do not actuate the valves. 

  • The cryo pump was regenerated to 1e-4 Torr about 2 years ago. It's pressure can be ~ 2 Torr with charcoal powder. It is a dirty system at room temperature.

  • Do not actuate VC1 and VC2, and keep its manual valve closed.

  • IF someone feels we should vent them for some reason, let us know here in the elog before Monday morning.



Wiring of the power, Ethernet, and indicator lights for the vacuum Acromag chassis is complete. Even though this crate will only use +24V DC, I wired the +/-15V connector and indicator lights as well to conform to the LIGO standard. There was no wiring diagram available, so I had to reverse-engineer the wiring from the partially complete c1susaux crate. Attached is a diagram for future use. The crate is ready to begin software developing on Monday. 


  7031   Wed Jul 25 16:55:01 2012 DenUpdatedigital noisenotch, lowpass filters

 Direct Form 2 is noisy in the first test. This is the one similar to Matt's in his presentation. Input signal was a sine wave at 1 Hz with small amplitude white noise x[n] = sin(2*pi*1*t[n]) + 1e-10 * random( [-1, 1] ). It was filtered with a notch filter: f=1Hz, Q=100, depth=210dB. SOS representation was calculated in Foton. Sampling frequency is 16kHz.

iir_psd.png        iir_time.png   iir_coh.png

DF2 output noise level is the same if I change white noise amplitude while DF1, BQF, LNF can follow it. Time series show quantization noise of DF2. I've plotted coherence of the signals relative to DF1, because non of the signals will be coherent to it at low frequencies due to fft calculations.  

In the second test the input was white noise  x[n] = random( [-1, 1] ) It was filtered with a 2 order low-pass butterworth filter with cut-off frequency f = 0.25 Hz. SOS representation was calculated in Python. Sampling frequency is 16kHz.

iir_psd_lowpass.png         iir_time_lowpass.png      iir_coh_lowpass2.png

In this test all implementations work fine. I guess dtt works with single precision and for that reason we see disturbance in coherence when we do the same test online.

  7034   Wed Jul 25 23:03:22 2012 ranaUpdatedigital noisenotch, lowpass filters

If the problem is the precision in DTT, then why would the noise change when the corner frequency of the filter is changed?

And how about checking for filter noise in the situation we saw online? 4th order low pass at 1 Hz or 8 Hz.

  7036   Thu Jul 26 10:22:03 2012 DenUpdatedigital noisenotch, lowpass filters


If the problem is the precision in DTT, then why would the noise change when the corner frequency of the filter is changed?

And how about checking for filter noise in the situation we saw online? 4th order low pass at 1 Hz or 8 Hz.

 This is because when we plot signals with sampling frequencies 2k and 16k with the same BW, we actually create psd/coherence using different numbers of points in FFT calculations as NFFT ~ fs/bw, fs-sampling frequency. So we secretly used 8 times more fft points for 16k signal then for 2k signal. Following plots demonstrate this effect. The first plot shows transfer function and coherence for filtering of 16k signal with butter('LowPass',4,8) and 2k signal with butter('LowPass',4,1)  when BW=0.1. There is a disturbance in coherence for 2k signal below 2 Hz. Now let's take BW=0.8 and plot transfer function and coherence for 16k signal. We can see the same effect of coherence disturbance.

same_bw.png    16384_bw0p8.png

The similar effect takes place when we change the cut-off frequency. The following plots show transfer function and coherence of two pairs of 2kHz signals. 4 order butterworth low-pass filter was used. For the first pair cut-off frequency was 1 Hz, for the second 10 Hz.  On the first plot BW=0.1 and there is a disturbance in coherence below 1 Hz. However on the second plot when BW=0.01, this effect is lost.

corners_bw0p1.png     corners_bw0p01.png

I guess my goal is to figure out when these effects come from fft calculations and when from digital filter noise.

  16060   Wed Apr 21 10:59:07 2021 ranaSummaryCamerasnote on new GigE cam @ 1064

Note from Stephen on more sensitive Baslers.

  10842   Wed Dec 24 08:25:05 2014 ranaConfigurationIOOnotes on MC locking

 I've updated the scripts for the MC auto locking. Due to some permissions issues or general SVN messiness, most of the scripts in there were not saved anywhere and so I've overwritten what we had before. 

After all of the electronics changes from Monday/Tuesday, the lock acquisition had to be changed a lot. The MC seems to catch on the HOM more often. So I lowered a bunch of the gains so that its less likely to hold the HOM locks.

A very nice feature of the Autolocker running on megatron is that the whole 'mcup' sequence now runs very fast and as soon as it catches the TEM00, it gets to the final state in less than 2 seconds.

I've also increased the amplitude of the MC2 tickle from 100 to 300 counts to move it through more fringes and to break the HOM locks more often. Using the 2009 MC2 Calibration of 6 nm/count, this is 1.8 microns-peak @ 0.03 Hz, which seems like a reasonable excitation.

Using this the MC has relocked several times, so its a good start. We'll have to work on tuning the settings to make things a little spicier as we move ahead.


That directory is still in a conflicted state and I leave it to Eric/Diego to figure out what's going on in there. Seems like more fallout from the nodus upgrade:

controls@chiara|MC > svn up

svn: REPORT of '/svn/!svn/vcc/default': Could not read chunk size: Secure connection truncated (https://nodus.ligo.caltech.edu:30889)

  7692   Fri Nov 9 08:11:57 2012 SteveUpdateAlignmentnothing moved - all good

 Oplevs and IP ANG are still centered. Why  do the SRM and PRM move 5X  more ?  I could not check the sensing voltages because the computer failed.

AS and REFL are looking the same as last night.



Attachment 1: opsingGOOD.png
Attachment 2: op8h.png
Attachment 3: 8amF.png
Attachment 4: keepfailing.png
  8243   Wed Mar 6 18:27:24 2013 JamieUpdateGeneralnow recording input TT channels to frames, but why no autoburt?

I spent some time trying to figure out how to get a record of the pointing of the input pointing tip-tilt (TT) channels.


Currently the TT pointing is done via the offset in the PIT/YAW filter banks, ie. C1:IOO-TT1_PIT_OFFSET, which is an EPICS record.  I added these channels to the C0EDCU.ini, which (I'm pretty sure) specifies which EPICS channels are recorded to frames.

controls@pianosa:~ 0$ grep C1:IOO-TT /opt/rtcds/caltech/c1/chans/daq/C0EDCU.ini 
controls@pianosa:~ 0$ 

I then confirmed that the data is being recorded:

controls@pianosa:~ 0$ FrChannels /frames/full/10466/C-R-1046657424-16.gwf | grep TT
controls@pianosa:~ 0$ 


The EPICS records for these channels *should* be recorded by autoburt, but Yuta noticed they were not:

controls@pianosa:~ 0$ grep -R C1:IOO-TT1_PIT_OFFSET /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2013/Mar/6/
controls@pianosa:~ 1$

The autoburt log seems to indicate some sort of connection problem:

controls@pianosa:! 130$ grep C1:IOO-TT1_PIT_OFFSET /opt/rtcds/caltech/c1/burt/autoburt/logs/c1assepics.log
pv >C1:IOO-TT1_PIT_OFFSET< nreq=-1
pv >C1:IOO-TT1_PIT_OFFSET.HSV< nreq=-1
pv >C1:IOO-TT1_PIT_OFFSET.LSV< nreq=-1
pv >C1:IOO-TT1_PIT_OFFSET.HIGH< nreq=-1
pv >C1:IOO-TT1_PIT_OFFSET.LOW< nreq=-1
C1:IOO-TT1_PIT_OFFSET ... ca_search_and_connect() ... OK
C1:IOO-TT1_PIT_OFFSET.HSV ... ca_search_and_connect() ... OK
C1:IOO-TT1_PIT_OFFSET.LSV ... ca_search_and_connect() ... OK
C1:IOO-TT1_PIT_OFFSET.HIGH ... ca_search_and_connect() ... OK
C1:IOO-TT1_PIT_OFFSET.LOW ... ca_search_and_connect() ... OK
C1:IOO-TT1_PIT_OFFSET ... not connected so no ca_array_get_callback()
C1:IOO-TT1_PIT_OFFSET.HSV ... not connected so no ca_array_get_callback()
C1:IOO-TT1_PIT_OFFSET.LSV ... not connected so no ca_array_get_callback()
C1:IOO-TT1_PIT_OFFSET.HIGH ... not connected so no ca_array_get_callback()
C1:IOO-TT1_PIT_OFFSET.LOW ... not connected so no ca_array_get_callback()
controls@pianosa:~ 0$ 

This is in contrast to successfully recorded channels:

controls@pianosa:~ 0$ grep C1:LSC-DARM_OFFSET /opt/rtcds/caltech/c1/burt/autoburt/logs/c1lscepics.log
pv >C1:LSC-DARM_OFFSET< nreq=-1
pv >C1:LSC-DARM_OFFSET.HSV< nreq=-1
pv >C1:LSC-DARM_OFFSET.LSV< nreq=-1
pv >C1:LSC-DARM_OFFSET.HIGH< nreq=-1
pv >C1:LSC-DARM_OFFSET.LOW< nreq=-1
C1:LSC-DARM_OFFSET ... ca_search_and_connect() ... OK
C1:LSC-DARM_OFFSET.HSV ... ca_search_and_connect() ... OK
C1:LSC-DARM_OFFSET.LSV ... ca_search_and_connect() ... OK
C1:LSC-DARM_OFFSET.HIGH ... ca_search_and_connect() ... OK
C1:LSC-DARM_OFFSET.LOW ... ca_search_and_connect() ... OK
C1:LSC-DARM_OFFSET ... ca_array_get_callback() nreq 1 ... OK
C1:LSC-DARM_OFFSET.HSV ... ca_array_get_callback() nreq 1 ... OK
C1:LSC-DARM_OFFSET.LSV ... ca_array_get_callback() nreq 1 ... OK
C1:LSC-DARM_OFFSET.HIGH ... ca_array_get_callback() nreq 1 ... OK
C1:LSC-DARM_OFFSET.LOW ... ca_array_get_callback() nreq 1 ... OK
controls@pianosa:~ 0$ 

In fact all the records in the c1assepics log are showing the same "not connected so no ca_array_get_callback()" error.  I don't know what the issue is.  I have no problem reading the values from the command line, with e.g. ezcaread.  So I'm perplexed.

If anyone has any idea why the c1ass EPICS records would fail to autoburt, let me know.

  7191   Wed Aug 15 11:44:35 2012 jamieSummaryLSCntp installed on all workstations


5) DTT wasn't working on rossa. Used the Date/Time GUI to reset the system time to match fb and then it stopped giving 'Test Timed Out'. Jamie check rossa ntpd.

ntp is now installed on all the workstations.  I also added it to the /users/controls/workstation-setup.sh script

  1642   Tue Jun 2 23:12:08 2009 robConfigurationComputersntp on op440m

I restarted ntpd on op440m to solve a "synchronization error" that we were having in DTT.  I also edited the config file (/etc/inet/ntp.conf) to remove the lines referring to rana as an ntp server; now only nodus is listed.

To do this:

log in as root

/usr/local/bin/ntpd -c /etc/inet/ntp.conf

  3721   Thu Oct 14 14:52:52 2010 Leo SingerConfigurationComputersnumpy, ipython, matplotlib, python-matplotlib installed on rossa

I installed the following packages on rossa:

numpy, ipython, matplotlib, python-matplotlib

  6547   Wed Apr 18 23:12:49 2012 DenUpdateCDSoaf

Adaptive filter outputs some non-zero signal in the OFF position


I turned "ON" one of them and c1lsc suspended, I've rebooted it and restarted models on c1lsc and c1sus.

Now it also outputs something non-zero though the first line of the adaptive code is "if(OFF) output=0.0; return;" May be another version of the code has been compiled.

Edit: Old version (~september) of the code and oaf model is running now. In the 2.1 code there was a link from src/epics/simLink to oaf code for each DOF. It seems that 2.5 version finds models and c codes in standard directories. I need to move working code to the proper directory.

  6548   Thu Apr 19 08:43:16 2012 JamieUpdateCDSoaf


Edit: Old version (~september) of the code and oaf model is running now. In the 2.1 code there was a link from src/epics/simLink to oaf code for each DOF. It seems that 2.5 version finds models and c codes in standard directories. I need to move working code to the proper directory.

 Yes, things have changed.  Please wait until I have things cleaned up before working on models.  I'll explain what the new setup is.

  6551   Thu Apr 19 22:18:24 2012 DenUpdateAdaptive Filteringoaf algorithm: old vs new

 Here are the issues that I found not quite accurate in the old oaf code:

1. There is no need to calculate the norm of the witness signal every time from zero: 

norm += (*pBufAdapt) * (*pBufAdapt); // add to the norm 

Every step the witness signal vector is the same except the first and last values

wit[i].norm += histAdpt[nCoeff]*histAdpt[nCoeff] - histAdpt[0]*histAdpt[0];

 This step will reduce the number of multiplications and summations from 3*M/k to 2*M/k, M - filter length, k - downsample ratio.

2. Old code filter corrects filter coefficients with a delay equal to k=downsample ratio (pretty big):

witness       o o o o o o o o o o o o o o o o o o o o o

error           o o o o o o o o o o o o o o o o o o o o o

We want the filter to work at green points and skip red points computing output and correcting coefficients at this time (downsample ratio in this example is 4). Old code

  • grabs error signal
  • calculates output during next k-1 red points and 1 green point
  • corrects coefficients using this error during next k-1 red points and 1 green point

But LMS algorithm should correct coefficients according to the latest error. As we calculate output and correct coefficients before the latest error signal will be available, we should change the order:

  • grabs error signal
  • corrects coefficients using this error during next k-1 red points and 1 green point
  • calculates output during next k-1 red points and 1 green point

This scheme is completely equivalent to the ordinary LMS algorithm, as now we correct coefficients according to the latest error signal and so do not add any delay.

3. So long soft start is probably not needed for the LMS filter, it makes the filter to converge longer 

// modify adaptation gain for soft start

    if( state.iWait < state.nFIR )


      adaptGain = 0.0;

      decayRate = 1.0;  // clear FIR coeffs after reset


As far as I understand this is done to prevent the filter from huge coefficients variations in the beginning when norm is not calculated yet. Instead we can just introduce some small

epsilon = 10.0;

to prevent the filter from divergence in the beginning 

delta = mu * error / (wit[i].norm + epsilon);

Though some soft start might be needed by not so long - it will take several minutes before the adaptation gain will take it's specified value. 

  6490   Thu Apr 5 18:24:55 2012 DenConfigurationAdaptive Filteringoaf starts to work

Today I tried to make the lms filter to work online. I played around with the signals (GUR1_X and MC_F) to pre-whiten them and in the end the following configuration worked out:

1. mu = 0.03, tau = 1e-5, downsample=8, nCoeff = 4000, delay = 5 (sample-and-hold delay is not included in the new code, it should be added here!)

2. witness pass: AA32 = cheby1("LowPass", 4, 1, 32) AND 0.1:0

3. witness adaptation path: AA32 AND AI32 = cheby1("LowPass", 4, 1, 32) AND 0.1:0

4. error path: AA32 AND 0.1:0 AND anti_1Hz. Before I added anti_1Hz filter oaf did nothing. This filter tries to approximate the actuator transfer function. Note, it is not in the witness adaptation path. This is some sort of whitening.

5. correction path: AI32, gain = -1

Convergence time ~ 5 mins. The performance of the filter is far not perfect compared to the offline implementation. But it deals with a stack though.


  13924   Thu Jun 7 10:26:36 2018 keerthanaUpdatePSLobserving the resonance signal corresponding to the injected frequency.

(Johannes, Koji, Keerthana)

The PLL loop ensures that the frequency difference between the PSL laser and the AUX laser is equal to the frequency we provide to the Local Oscillator (LO) with the help of a Marconi. Only a small pick off part of both the AUX and PSL lasers are going to the PLL loop. The other part of both the lasers are going to the interferometer. Before entering into the optical fibre, the AUX laser passes through an AOM which changes its frequency by an amount of 80MHz. When the PLL is locked, the frequency coming out of the PLL will be equal to the frequency set up in the Marconi (fm). When it passes through AOM, the frequency becomes fdiff = fm ±80 MHz. If this frequency beam and the PSL laser beam is aligned properly, and if this frequency is equal to the product of an integer and the free spectral range of the cavity, this will resonate in the cavity.  Then we expect to get a peak in the ETM transmission spectrum corresponding to the frequency we injected through the optical Fibre.

Through out the experiment we need to make sure that the PSL is locked. Thus, the signal detected by the photo detector when only PSL is resonating inside the cavity, act as a DC signal. Then we give a narrow scan to the Marconi. When fdiff = N*FSRy this condition is satisfied, we will observe a peak in the output. Here FSRy  is the free spectral range of the cavity which is approximately equal to 3.893 MHz.

Yesterday afternoon, Johannes, Koji and myself tried to observe this peak. We aligned the cavity by observing the output signal from the AS100 photo detector. We made the alignment in such a way that the intensity output getting from this photo detector is maximum. We used a Spectrum analyser to see the output. After that we connected a photo detector to collect the YEND transmission signal from the ETM mirror. We used a lens to focus this directly to the photodetector. Then we connected this photodetector to the spectrum analyser, which was located near the AS table. We took a large cable to meet this purpose. But still the cable was not lengthy enough, so we joined it with another cable and finally connected it with the spectrum analyser. Then we gave a scan to the Marconi from 51 MHZ to 55 MHz. We repeated this experiment with a scan of 55 MHz to 59 MHz also. We repeated this a few times, but we were not able to see the peak.

We assume that this can be because of some issue with the alignment or it can be because of some issue with the photo detector we used. We would like to repeat this experiment and get the signal properly.

I am attaching a flow chart of the setup and also a picture of the mirrors and photo detector we inserted in the Y-End table.

Attachment 1: photodetector_alignment.jpg
Attachment 2: design1.PNG
  13930   Thu Jun 7 22:36:09 2018 not keerthanaUpdatePSLobserving the resonance signal corresponding to the injected frequency.

I worked a bit on the PSL table today

  13931   Fri Jun 8 00:36:54 2018 gautamUpdatePSLobserving the resonance signal corresponding to the injected frequency.

It isn't clear to me in the drawing where the Agilent is during this measurement. Over 40m of cabling, the loss of signal can be a few dB, and considering we don't have a whole lot of signal in the first place, it may be better to send the stronger RF signal (i.e. Marconi pickoff) over the long cable rather than the weak beat signal from the Transmission photodiode. 

  4131   Tue Jan 11 01:05:29 2011 kiwamuUpdateLSCobtained Xarm PDH signal

[Jenne, Zach, Kiwamu]


 We made some efforts to lock the X arm cavity with the infrared beam.

We eventually obtained the PDH signal from a photo diode at AS port, we are still in the mid way of the lock.

The PDH signal now is going into c1lsc's ADC.

We have to make sure which digital channel corresponds to our PDH signal,


(what we did)

- split the LO signal, which comes from a Marconi, just before the EOM into two path.

     One is going to the EOM and the other is going to the AP table for the demodulation, The driving frequency we are using is 11MHz.

- put RF amplifiers to make the RF signal bigger. The raw signal was small, it was about ~-50 dBm in the spectrum analyzer.

   So we connected two ZLN amplifiers. Now the RF signal is at about 0 dBm

- connected the LO and RF signals to a mixer.  Additionally we put a 9.5-11.5 MHz bandpass filter at the LO path since there was some amounts of 29.5MHz due to the RF reflection at the EOM resonant box.

     After a low pass filter by SR560 the signal shows typical PDH behaviors.

- strung a BNC cable which connects the demodulated signal and c1lsc.

    In order to connect the signal to the current working ADC, we disconnected AS166_I from a whitening board and plug our cable on it.

- tried checking the digital signal but we somehow couldn't configure DAQ setting, So actually we couldn't make sure which channel corresponds to our signal.


  15026   Thu Nov 14 23:56:18 2019 ranaUpdateLSCoff the bad Violin filters

We turned off many excessive violin mode bandstop filters in the LSC.

Due to some feedforward work by Jenne or EQ some years ago, we have had ~10 violin notches on in the LSC between the output matrix and the outputs to the SUS.

They were eating phase, computation time, and making ~3 dB gain peaking in places where we can't afford it. I have turned them off and Gautam SDF safed it.

Offensive BS shown in brown and cooler BS shown in blue.

To rotate the DTT landscape plot to not be sideways, use this command (note that the string is 1east, not least):
pdftk in.pdf cat 1east output out.pdf

Attachment 1: out.pdf
  15028   Fri Nov 15 11:58:12 2019 gautamUpdateLSCoff the bad Violin filters

The clue was that the loop X arm POX loop looked to have low (<3dB)) gain margin around 600 Hz (and again at 700 Hz). Attachment #1 shows a comparison of the OLTF for this loop (measured using the IN1/IN2 method) before and after our change. We hypothesize that one of the violin filters that were turned off had non-unity DC gain, because I had to lower the loop gain by 20% after these turn-offs to have the same UGF. I updated the snap files called by the arm locking scripts.

I think I caught all the places where the FM settings are saved, but some locking scripts may still try and turn on some of these filters, so let's keep an eye on it.


We turned off many excessive violin mode bandstop filters in the LSC.

Attachment 1: violinFix.pdf
Attachment 2: newViolinConfig.png
  1869   Sat Aug 8 17:23:29 2009 ranaUpdatePEMoffensive 2 Hz sine wave removed

Friday, we were seeing a 2 Hz harmonic series in all of the PEM channels. Today I found that some bad person had put in a 4V (!) signal into one of the channels with a signal generator. The generator was also sneakily stuck way back inside the DCU rack. NO SECRET SIGNAL INJECTIONS!

Since the ADC has a 2Vpk range, this was saturating and putting in harmonics in all the adjacent channels. I disconnected it and turned off the function generator.

  15193   Thu Feb 6 16:14:44 2020 ranaUpdateGeneraloffice area temperature

I changed the office area thermostate near Steve's desk from 68F to 73F today. Please do not change it.

If anyone from facilities comes to adjust something, please put the details in the elog on the same day so that we can know to undo that change rather than chase down other drifts in the system.

  15196   Fri Feb 7 02:41:28 2020 KojiUpdateGeneraloffice area temperature

Not sure what's wrong, but the workstation desk is freezing cold again and the room temp is 18degC (64degF).

  6642   Fri May 11 23:33:41 2012 DenUpdateAdaptive Filteringoffline vs online

I've compared offline Wiener filtering with online static + adaptive filtering for MC_F with GUR1_XYZ and GUR2_XYZ as witness signals


Note: online filter works up to 32 Hz (AI filter at 32 Hz is used). There is no subtraction up from this frequency, just MC_F was measured in different times for online and offline filtering. This difference in MC_F in frequency range 20-100 Hz showed up again as before with microphone testing.  One can see it in 1 minute. Smth is noisy.

Reasons why online filter is worse then offline:

1. FIR -> IIR conversion produces error. Now I'm using VECTFIT approximation with 16 poles (splitting into 2 filter banks), this not enough. I tried to use 50 and split them into 5 filter banks, but this scheme is not working: zpk -> sos conversion produces error and the result filter works completely wrong.

2. Actuator TF. VECTFIT works very good here - we have only 1 resonance. However, it should be measured precisely.

3. Account for AA and AI filters that rotate the phase at 1-10 Hz by ~ 10 degrees.

  5806   Fri Nov 4 05:24:56 2011 kiwamuUpdateLSCoffset introcuded in MC and IFO-configure script modified

[Offsets in MC]

 I have introduce an offset in MC2 PIT because the PZT1 again started railing.

Right now the PZT1 EPICS value is within the range happily.

Please keep this MC eigen axis as a nominal configuration.


[IFO-configure script]

 I have modified the IFO configure scripts such that XARM and YARM are locked with POX11 and POY11 respectively.

A big advantage in use of POX and POY is that we don't need to misalign ITMs when we align each arm.

Those scripts are now available from the C1IFO_CONFIGURE screen as usual.

  11732   Wed Nov 4 20:16:58 2015 yutaroUpdateElectronicsoffset voltage vs. gain of common mode servo

At 1Y2 rack, I measured offset voltage of the common mode servo (D040180-B) with the gain of it varied.

For now, all signal cables that come into or go out of the common mode servo are not plugged.


I will upload the data I took and report the result later.

  11737   Thu Nov 5 10:48:21 2015 yutaroUpdateElectronicsoffset voltage vs. gain of common mode servo

I report the results of the measurement to know how offset voltage of common mode servo changes when the gain is changed.


- Motivation: If discontinuous change of the offset happens when we change the gain, it could cause saturation somewhere and so make the length control down. So, we want to estimate effect of such discontinuous change.


- Method: In 1 (or In 2) was terminated with 50 ohm, and the output voltage at Out 2 was measured with a multimeter (D040180-B).


- Results are shown below. Acquired data are attached in .zip.

The upper shows input equiv. offset. The lower shows offset measured at Out 2.

As for both In1 and In2, strange behaviors can be seen between -17 dB and -16 dB.

This is because 5 amplifiers (or attenuators) are simultaneously enabled/disabled here. Similar situation occurs every change of 8 dB gain. 

Attachment 2: offsets.zip
  9968   Sun May 18 14:36:04 2014 denUpdateLSCoffsets in 3f and drmi stable lock on 1f

Eric, Den

We noticed that PRMI RIN is high when the cavity is locked on RELF33 I&Q signals. We compared the level of power fluctuations when PRMI was locked using REFL11, REFL55 and REFL 33. Attached plot "prmi_rin" shows the spectra.

Then we excited PRM and measured length to RIN coupling when PRMI was locked on REFL33 I&Q. DC offset of PRCL is only 3%. But MICH offset seems to be ~nm. When we gave offset of -15 cnts to the servo, power fluctuations improved by a factor of few.

Then we looked at DRMI. It seems that SRC macroscopic length is off but we still could lock it stably. To account for macroscopic length detuning we had to rotate REFL55 phase from 25 degrees to 50 degrees. Power at AS port increased by factor of ~2 compared to PRMI configuration. SPOP18 is decreased only by 30%. Attached plot "drmi_power" shows POP18, POP90, POPDC and ASDC in PRMI and DRMI configurations.

Plot "src_ol" shows srcl OL transfer function. UGF is 70 Hz. We have also centered SRM OL and copied the servo filters from PRM, gains are set to keep UGF at ~0.1 Hz and 7 Hz

This is a more detailed procedure:

1. Phase: REFL11: 19 degree, REFL55: 50 degrees (25 degrees for PRMI configuration)

2. Input matrix:

PRCL   0.15 0 0 REFL11I
MICH = 0 0.15 0 REFL55Q
SRCL   -0.09 0 1 REFL55I

3. Servo parameters:

PRCL: gain = -0.02, FM4,5 + trigger FM2,3,6,9

MICH: gain = 0.8, FM4,5 + trigger FM2

SRCL: gain = 0.25, FM4,5 + trigger FM2,3

4. Triggering:

signal is SPOP22 , levels 40:25

Attachment 1: prmi_rin.pdf
Attachment 2: drmi_power.png
Attachment 3: src_ol.pdf
  14435   Tue Feb 5 10:22:03 2019 chubUpdate oil added to RP-1 & 3

I added lubricating oil to roughing pumps RP1 and RP3 yesterday and this morning.  Also, I found a nearly full 5 gallon jug of grade 19 oil in the lab.  This should set us up for quite a while.  If you need to add oil the the roughing pumps, use the oil in the quart bottle in the flammables cabinet.  It is labeled as Leybold HE-175 Vacuum Pump Oil.  This bottle is small enough to fill the pumps in close quarters.

  10560   Thu Oct 2 14:36:52 2014 steveUpdatePEMoil drops on vertex crane



 KroneCrane Fred inspected and certified the 3 40m cranes for 2014. The vertex crane crane was load tested at fully extended position.

 Small oil drops were found during prevent inspection of the vertex crane. They were wiped off. It took 231 days to grow this size.

Attachment 1: VertexOilDrops.jpg
  12871   Mon Mar 6 16:32:36 2017 SteveUpdateGeneralold NPRO

16 years old Lightwave NPRO M126-1064-700, sn 415 power output is tripping continously to zero.

The Lightwave Controller 125/126-OPN-POS sn516 was used in this test. Settings were lowered to close to nominal values without any success.

One can not determine what is broken: head or controller. This NPRO head was under Manasa's desk.

  4866   Thu Jun 23 10:35:12 2011 steveUpdateComputersold computers leaving the lab

Rod Luna picked up these computers for Larry Wallace yesterday: Dell Inspiron 530, Dell Dimension 4600 and SunBlade 1000

Attachment 1: P1070905.JPG
Attachment 2: P1070904.JPG
Attachment 3: blade1000.JPG
  12162   Thu Jun 9 15:14:46 2016 jamieUpdateCDSold fb restarted, test of new daqdon fb1 aborted for time being

I've restarted the old daqd on fb until I can figure out what's going on with the symmetricom driver on fb1.

Steve:  Jamie with hair.... long time ago

Attachment 1: Jamie.jpg
  10435   Thu Aug 28 08:31:16 2014 SteveUpdateGeneralone good day
Attachment 1: 1goodDay.png
Attachment 2: 1gooday.png
  13631   Tue Feb 13 21:22:44 2018 SteveUpdateSEIone load cells tested

Gautam and Steve,

The "called 225 lbs" steel crane load measured right on 102 kg

The trick to the measurment to maintain 1 mm gap to the central cilynder of the load cell.

The lead plate stabilized the large load.

gautam: some additional notes:

  1. the wiring on the Omega controller unit as given to us was wrong - I had to fix this on the D-sub connector in order to get the load cell to work. something to check for the other units.
  2. the main difficulty in doing this calibration run was that the readback is very sensitive to tilts of the load relative to the sensor.
  3. the problem is complicated by the fact that the load cell itself does not have a flat surface - it has a ring that protrudes above the flat face of the cylindrical load cell by a few mm as Steve mentioned.
  4. so in order to measure the weight of our stacks, we have to mitigate this problem and ensure that the full load of the stack is normally incident on the load cell - if the load cell itself is somehow torqued during the measurement because of the distribution of the load on it being uneven, we get an inaccurate measurement.
  5. In this calibration measurement, we think the error is <1% (true mass is 102kg, we measure 104kg on the meter which seems reasonable as the sum of the donut + lead plate)

Attachment 1: as_measured_102kg.jpg
Attachment 2: sensor.jpg
Attachment 3: 1500lbs_load__cell.jpg
  2089   Tue Oct 13 10:31:11 2009 ZachUpdatePSLone more time

I am at the PSL table taking what is hopefully the last set of pictures for the diagram. Woohoo.

  2090   Tue Oct 13 10:50:58 2009 ZachUpdatePSLone more time


I am at the PSL table taking what is hopefully the last set of pictures for the diagram. Woohoo.

 I'm out, HEPAs are back at 20%.

  7708   Tue Nov 13 21:05:35 2012 DenUpdateAdaptive Filteringonline and simulation

For a last few days I've been working on oaf and simulink model to simulate it. First I did online subtraction from MC when MC_L path was enabled. Inside my code I've added a sum of squares of filter coefficients so we can monitor convergence of the filter.

coeff.png     online.png

To to this I've measured path from OAF output to input without AA and AI filters. Then made a vectfit using 2 poles and zeros. Foton command

zpk( [-2.491928e+03;5.650511e-02], [-4.979872e+01;-3.278776e+00], 6.011323e+00)

mag.png    phase.png

My simulink model consists of 3 parts:

  • cavity with seismic noise at low frequencies, 1/f^2 noise at medium frequencies and white noise at high frequencies
  • this cavity is locked using feedback compensation filters that we use to lock arms
  • locked cavity with adaptive filter

Adaptive filter in the model uses online c-code. It is connected to simulink block through an S-function. Sampling frequency of the model is 10 kHz. It works fairly fast - 1 sec of simulation time is computed in 1 sec.

overview.png       af.pngsim.png  sim_coeff.png

I've tested FxLMS algorithm and MFxLMS algorithm that is faster. I plan to test 2 iir adaptive algorithms that are already coded.

  7042   Thu Jul 26 21:31:44 2012 DenUpdatedigital noiseonline biquad works


   Still I do not like huge (2n+1) harmonics in the output of the biquad filter, I do not get them in the simulations. They are absent in the time series as well. So this is not a psd-estimation effect. 

 Excitation generator created these harmonics. When I applied low-pass butterworth filter, I've got the result of online filtering close to simulations. On the second graph blue is biquad filter output spectrum, red corresponds to DF2. 1 Hz sin wave was filtered with a notch filter of Q=100, depth=300 at 1 Hz.

df2_bqf_lp.png    df2_bqf_lp_spec.png

  6297   Sat Feb 18 18:29:38 2012 DenUpdateAdaptive Filteringonline filtering

I tried to filter MC_F from seismic noise measured by GUR1 seismometer. I've used 8000 tap filter, downsample ratio=8, delay=1. In the Figure the output of the filter is presented with MC_F signal.


We can see that output is close to the MC_F, but the phase for some reason is not zero. It should not be at 1 Hz - 10 Hz due to the actuator. But below these frequencies I do not see any reasons for the output phase to differ from MC_F phase. But it is possible, the phase of the actuator is evaluated very rough and the adaptive filter can't match it.

  6241   Tue Jan 31 17:13:49 2012 steveUpdateIOOonly the PSL laser is off


The 2W PSL laser is turned off.  The danger laser lights are not illuminated at the entry doors because of malfunctioning electronic circuit!!!

Laser safety glasses are still required!  Other lasers are in operation!

  111   Fri Nov 16 14:11:26 2007 tobinUpdateComputersop140
Alan called to say that Phil Ehrens will be coming by to take op140 off our hands.
  112   Fri Nov 16 14:31:43 2007 tobinUpdateComputersop140 disks
Phil Ehrens stopped by and took op140's disks.
Attachment 1: DSC_0173.JPG
  10084   Fri Jun 20 19:07:44 2014 ranaUpdateComputer Scripts / Programsop340m DNS

I had forgotten to fix the DNS setup on op340m and so our slow, perl, PID loops for the laser were not running well (and that's why the FSS-FAST has been saturating).

I edited /etc/resolv.conf on there and then did /usr/sbin/reboot as super-user.

op340m:~>more /etc/resolv.conf
domain martian
Fri Jun 20 19:06:37 PDT 2014

The FSSSlowServo.pl now seems to be holding the NPRO PZT to ~6 V. I twiddled the PID settings a little bit to make sure nothing was squirrelly. Seems OK. Time constant of the loop is ~1 minute.

As a reminder, op340m runs our autoburt for all the FE machines, VME IOCs, does the watchdog threshold rampdown, and also the RefCav and NPRO temperature control.

  10095   Tue Jun 24 22:46:15 2014 ericqUpdateComputer Scripts / Programsop340m crons


The FSSSlowServo.pl now seems to be holding the NPRO PZT to ~6 V. I twiddled the PID settings a little bit to make sure nothing was squirrelly. Seems OK. Time constant of the loop is ~1 minute.

As a reminder, op340m runs our autoburt for all the FE machines, VME IOCs, does the watchdog threshold rampdown, and also the RefCav and NPRO temperature control.

 We had fiddled with the scripts/general/scripto_cron script to try and get the MC auto locker working on ottavia, but in doing so broke op340m's reliance on it to run it's cron jobs, like FSSSlowServo.

I've reverted scripto_cron to its original state, and the FSS slow servo starts up again.  

However, scripts like this that we want to always have on seem to be a better fit, to me, for the init system, like we do with daqd and nds on the FB. op340m's inittab looks different than what I'm used to, so I'm not making any changes; this is just a thought. 

MC autolocker is still being ran from an Ottavia GUI terminal; I'll try to get it consistently running on megatron, as suggested in  ELOG10039, now that caget/caput issues seem to be sorted. 

Addendum: I've changed the MC auto locker script to have megatron as its host. Haven't yet gotten it to run automatically; it's running in a detached tmux terminal. I'll finish it up tomorrow. 

  11624   Mon Sep 21 00:51:36 2015 ranaUpdateGeneralop340m, autoburt cron =? megatron

I modified the perl script which does our hourly autoburt so that it can run on megatron instead of op340m (old Solaris machine). Nothing major, just some path stuff. That was the last function of op340m that I know of, so after a week of watching this we ought to be able to power it off and send it to e-waste.

Seems to work so far. It complains about some models that aren't running but mostly it reports successful snapshot taking based on the .req files.

Unfortunately, it seems that its only doing the new target directory, so its missing all of our old VME machines which still use the /cvs/cds/caltech/target area.

But I think Gautam and Jamie and Aidan have volunteered to start our slow controls upgrade by moving the EX slow controls to Acromag and into the new target area. We ought to modify the CRON to point at the old directory for now, but its a temporary fix hopefully.

ELOG V3.1.3-