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 Typeup Category Subject
  11564   Thu Sep 3 02:12:08 2015 ranaUpdateCDSSimulink Webview updated

Back in 2011, JoeB wrote some entries on how to automatically update the Simulink webview stuff.

Somehow, the cron broke down over the years. I reran the matlab file by hand today and it worked fine, so now you can see the up to date models using the internet.


  11565   Thu Sep 3 02:30:46 2015 ranaUpdateCDSc1cal time reduced by deleting LSC sensing matrix

I experimented with removing somethings here and there to reduce the c1cal runtime. Eventually I deleted the LSC Sensing Matrix from it.

  • Ever since the upgrade, the c1cal has gone from 60 to 68 usec run time, so its constantly over.
  • Back when Jenne set it up back in Oct 2013, it was running at 39 usec.
  • The purely CAL stuff had some wacko impossible filters in it: please don't try to invert the AA filters making a filter with multiple zeros in it Masayuki.
  • I removed the weird / impossible / unstable filters.
  • I'm guessing that the sensing matrix code had some hand-rolled C-code blocks which are just not very speedy, so we need to rethink how to do the lockin / oscillator stuff so that it doesn't overload the CPU. I bet its somewhere in the weird way the I/Q signals were untangled. My suggestion is to change this stuff to use the standard CDS lockin modules and just record the I/Q stuff. We don't need to try to make magnitude and phase in the front end.

After removing sensing matrix, the run time is now down to 6 usec.

  11566   Thu Sep 3 08:53:55 2015 SteveUpdateSUSETMY Oplev laser power is falling

Rana, Steve

We investigated the ETMY oplev table set up and did not find a red herring.

Two 2 years  vs one day plot below.

ps: thanks  Q for fixing  DTT, the auto scaling is not working at sampling rate 10 min and 1 hr period?? surprise


Attachment 1: ETMYoplev2y.png
  11567   Thu Sep 3 13:25:40 2015 ranaUpdateCDSSimulink Webview updated

added the cron script for this to megatron to run at 8:44 AM each morning. Here's the new MegaCron attached :-()-

** it takes ~13 minutes to complete on megatron

Attachment 1: crontab_150903.rtf

# m h  dom mon dow   command
#0 */1 * * * bash /home/controls/public_html/summary/bin/c1_summary_page.sh > /dev/null 2>&1
#15 5 * * * /ligo/apps/nds2/nds2-megatron/test-restart

# MEDM Screen caps for the webpage
2,13,25,37,49 * * * * /cvs/cds/project/statScreen/bin/cronjob.sh

# op340m transplants -ericq
... 18 more lines ...
  11568   Thu Sep 3 17:15:26 2015 ericqUpdateLSCIR beatnote confusion

I was thinking that the "FOSC" product line (which is called a "coupler" instead of a "splitter/combiner") was what we wanted. 

Koji brought to my attention that the 90/10 splitters we already have are of this line. So, I rigged a few up to shine a hopefully beating pair of fields on the fiber coupled thorlabs PD. 

I was able to get ~80uW each of PSL and AUX X light on the PD, which produced a -10dBm beatnoteyes Thus, I think these FOSC splitters are indeed what we want. 

I then threw this IR beatnote at our ALS signal chain. The beatnote was too big to throw through our ~+27dB RF amps, so I just sent the -10dBm over to the LSC rack.

The IR beat spectrum is somwhat noisier from 10-100Hz, but, more interesting, is that the sub-4Hz noise is identical in the two beats, and very coherent. This excludes ALS noise arising from anything happening in the green beat optics on the PSL table.

Obviously, the high frequency noise is largely the same and coherent too, but also coherent with the AUX X PDH control signal, so it is understood. 

Attachment 1: GREENvIRbeats.pdf
  11570   Fri Sep 4 00:58:29 2015 ranaUpdateCDSsoldering the Generic Pentek interface board

Q and Ignacio were taking a second look at the Pentek interface board which we're using to acquire the POP QPD, ALS trans, and MCF/MCL channels. It has a differential intput, two jumper able whitening stages inside and some low pass filtering.

I noticed that each channel has a 1.5 kHz pole associate with each 150:15 whitening stage. It also has 2 2nd order Butterworth low pass at 800 Hz. Also there's a RF filter on the front end. We don't need all that low passing, so I started modifying the filters. Tonight I moved the 800 Hz poles to 8000 Hz. Tomorrow we'll move the others if Steve can find us enough (> 16) 1 nF SMD caps (1206 NPO).

After this those signals ought to have less phase lag and more signal above 1 kHz. Since the ADC is running at 64 kHz, we don't need any analog filtering below 8 kHz.

  11571   Fri Sep 4 04:05:51 2015 ericqUpdateLSCDRMI locked on 1F and 3F

Thanks to some expertly timed coffee from Ignacio, I have been able to achieve indefnite locks of the DRMI, first on a 1F/3F mix (P:REFL11, S: REFL165, M:AS55), and then purely on 3F (P:REFL33, S:REFL165, S:REFL165). MICH is currently actuated on the ITMs. 

I saved a snapshot of the current settings so I don't lose my settings. I think one thing that prevented earlier recipies from working is that whitening gains may have changed, which we don't typically note down when reporting input matrix settings

My current settings for 3F locking:


+30dB whitening gain, +136 demod phase

PRCL = 9 x I - 200 counts


+24dB whitening gain, +3 demod phase

SRCL = 1 x I, MICH = 5 x Q - 1000counts

MICH: G=-0.03; Acq FM4/5; Trig 2/3/6/9

PRCL: G=-0.003; Acq FM4/5; Trig 1/2/6/9

SRCL: G=0.2; Acq FM4/5; Trig 2/3/6/9

I've injected excitations into the control filter outputs via the LSC-FFC FMS (and notched the frequencies in the control filters themselves), and noted GPS times for offline sensing analysis. (Namely the 10 minutes following 1125398900)

Handing off to pure 3F was a little finicky at first, I needed to use some pretty large offsets in the MICH_B and PRCL_B FMs. (-1000 and -200 counts respectively). Once these offsets were found, the DRMI can acquire on 3F. Alignment is pretty important, too.  Acquiring is much faster when the loop gains are "too high." i.e. I see a fair amount of gain peaking at ~300Hz. Nevertheless, things are stable enough as is that I didn't feel like digging into reducing the gains to quieter values. 

  11572   Fri Sep 4 04:12:05 2015 ericqUpdateComputer Scripts / ProgramsMATLAB down on all workstations

There seems to be something funny going on with MATLAB's license authentication on the control room workstations. Earlier today, I was able to start MATLAB on pianosa, but now attempting to run /cvs/cds/caltech/apps/linux64/matlab/bin/matlab -desktop results in the message: 

License checkout failed.
License Manager Error -15
MATLAB is unable to connect to the license server. 
Check that the license manager has been started, and that the MATLAB client machine can communicate
with the license server.

Troubleshoot this issue by visiting: 

Diagnostic Information:
Feature: MATLAB 
License path: /home/controls/.matlab/R2013a_licenses:/cvs/cds/caltech/apps/linux64/matlab/licenses/license.dat:/cv
Licensing error: -15,570. System Error: 115

  11573   Fri Sep 4 08:00:49 2015 IgnacioUpdateCDSRC low pass circuit (1s stage) of Pentek board

Here is the transfer function and cutoff frequency (pole) of the first stage low pass circuit of the Pentek whitening board.


R1 = R2 = 49.9 Ohm, R3 = 50 kOhm, C = 0.01uF. Given a differential voltage of 30 volts, the voltage across the 50k resistor should be 29.93 volts.

Transfer Function: 

Given by, 

H(s) = \frac{1.002\text{e}06}{s+1.002\text{e}06}

So low pass RC filter with one pole at 1 MHz.

I have updated the schematic, up to the changes mentioned by Rana plus some notes, see the DCC link here: [PLACEHOLDER]

I should have done this by hand...crying

Attachment 1: circuit.pdf
  11574   Fri Sep 4 09:23:32 2015 IgnacioUpdateCDSModified Pentek schematic

Attached is the modifed Pentek whitening board schematic. It includes the yet to be installed 1nF capacitors  and comments. 

Attachment 1: schematic.pdf
schematic.pdf schematic.pdf schematic.pdf
  11575   Fri Sep 4 09:36:48 2015 SteveUpdateLSCIR beatnote confusion.....



I was thinking that the "FOSC" product line (which is called a "coupler" instead of a "splitter/combiner") was what we wanted. 

Koji brought to my attention that the 90/10 splitters we already have are of this line. So, I rigged a few up to shine a hopefully beating pair of fields on the fiber coupled thorlabs PD. 

I was able to get ~80uW each of PSL and AUX X light on the PD, which produced a -10dBm beatnoteyes Thus, I think these FOSC splitters are indeed what we want. 

I then threw this IR beatnote at our ALS signal chain. The beatnote was too big to throw through our ~+27dB RF amps, so I just sent the -10dBm over to the LSC rack.

The IR beat spectrum is somwhat noisier from 10-100Hz, but, more interesting, is that the sub-4Hz noise is identical in the two beats, and very coherent. This excludes ALS noise arising from anything happening in the green beat optics on the PSL table.

Obviously, the high frequency noise is largely the same and coherent too, but also coherent with the AUX X PDH control signal, so it is understood. 

Single mode coupler, 2x2, 1064nm +/-20nm, 50/50 ratio, 900micron loose tube jacket, Hi1060flex fiber, 1m fiber length, FC/APC connectors

Four of these items ordered yesterday from http://afwtechnologies.com.au/sm_coupler.html

  11577   Fri Sep 4 15:20:31 2015 ericqUpdateLSCVertex Sensing

I've now made a collection of sensing matrix measurements. 

In all of the plots below, the radial scale is logarithmic, each grid line is a factor of 10. The units of the radial direction are calibrated into demod board output Volts per meter. The same radial scale is used on all plots and subplots.

I did two PRMI measurements: with MICH locked and excited with either the ITMS or the BS + PRM compensation. This tells us if our PRM compensation is working; I think it is indeed ok. I though I remembered that we came up with a number for the SRM compensation, but I haven't been able to find it yet. 

The CARM sensing int he PRFPMI measurement has the loop gain at the excitation frequency undone. All excitations were simultaneously notched out of all control filters, via the NotchSensMat filters. 

The angular scale is set to the analog I and Q signals; the dotted lines show the digitial phase rotation angle used at the time of measurement. 

Attachment 1: PRFMI_ITM.pdf
Attachment 2: PRFMI_BS.pdf
Attachment 3: DRMI.pdf
Attachment 4: PRFPMI.pdf
  11578   Fri Sep 4 20:06:23 2015 ranaUpdateLSCDRMI locked on 1F and 3F

Nice going. I think the LLO / LHO scheme is to acquire on 1F and then cdsutils avg to get the 3F offsets. The thinking is that that 1F signals have less intrinsic offset than the 3F signals, so we want to be use digital offsets for the 3F locks.

  11579   Fri Sep 4 20:42:14 2015 gautam, ranaUpdateCDSCheckout of the Wenzel dividers

Some years ago I bought some dividers from Wenzel. For each arm, we have x256 and a x64 divider. Wired in series, that means we can divide each IR beat by 2^14.

The highest frequency we can read in our digital system is ~8100 Hz. This corresponds to an RF frequency of ~132 MHz which as much as the BBPD could go, but less than the fiber PDs.

Today we checked them out:

  1. They run on +15V power.
  2. For low RF frequencies (< 40 MHz) the signal level can be as low as -25 dBm.
  3. For frequencies up to 130 MHz, the signal should be > 0 dBm.
  4. In all cases, we get a square wave going from 0 ~ 2.5 V, so the limiter inside keeps the output amplitude roughly fixed at a high level.
  5. When the RF amplitude goes below the minimum, the output gets shaky and eventually drops to 0 V.

Since this seems promising, we're going to make a box on Monday to package both of these. There will one SMA input and output per channel.

Each channel will have a an amplifier since this need not be a low noise channel. The ZKL-1R5 seems like a good choice to me. G=40 dB and +15 dBm output.

Then Gautam will make a frequency counter module in the RCG which can do counting with square waves and not care about the wiggles in the waveform.

I think this ought to do the trick for our Coarse frequency discriminator. Then our Delay Box ought to be able to have a few MHz range and do all of the Fast ALS Carm that we need.

Attachment 1: TEK00000.PNG
Attachment 2: TEK00001.PNG
Attachment 3: TEK00002.PNG
  11582   Mon Sep 7 19:46:46 2015 ranaUpdatePEMSeismic BLRMS filters

As it turned out, the "STS" BLRMS filters were all a mess, so I fixed them up today:

  • BP and LP filters were non-existent for the 2 low frequency bands: 0.01-0.03 & 0.03-0.1 Hz. The 0.01-0.03 is just seeing tilt noise (its big in X & Y, but not in Z), but the other band is able to cleanly see the primary microseism at 0.06 Hz.
  • There was some mixup and some BP filter banks had low pass filters while one of the LP banks had a BP filter.
  • There were different filters between the X, Y & Z directions.
  • The low pass filters had enough ringing in the impulse response that their outputs could sometimes go negative and make the SQRT block output NaN.

After tuning:

  • All bandpass filters are 4th order Butterworth bandpass with the corners at the band edges (e.g. 1- 3  Hz)
  • All low pass are the same, just scaled by the frequency band. They have a pair of real poles and a pair of 35 deg poles. The pole frequencies are set so that there is 40 dB of attenuation at twice the frequency of the low end of the bandpass. i.e. for the 1-3 Hz band, the low pass has > 40 dB atten at 2 Hz.
  • The 3-10 and 10-30 Hz bands use the same low pass as the 1-3 Hz band, since I don't want to see aliasing in the EPICS readouts. I don't think we need faster than 1 Hz readback of the RMS.
  • Confirmed with FOTON that the impulse response for the LP filters are positive for all t >0.

The "C1:PEM-SEIS_STS_1" filter banks are currently empty, so the signal is just in ADC counts. However, by amazing luck, this seems to be the right gain (within a factor of 2) to put the signal into units of microns / second. According the the schematic (D1000749), the default gain of 110 can be switched to make the whole box just have a gain of 2 (differential in, differential out). I wonder if anyone, like Jenne, knows if this is what we have? There's no elog I found about setting the gain switch.

According to the manual, the gain is ~1175 V/(m/s). Our ADC gain should be (2^16)/(40). So:

cal_gain = 1175 * 2 * 65536 / 40  ==>> 0.26 (m/s)/counts

I have put this into the STS_1_X,Y,Z filter modules in c1pem so that these channels are now calibrated. I also put the first few s-domain poles/zeros into the filter based on the manual so that the magnitude in the 10-30 Hz band is correct-ish now.

* Does anyone know how to center the masses on this thing?

Attachment 1: T240_150907.png
  11583   Tue Sep 8 20:30:44 2015 ranaUpdateIOOMC WFS relief re-commissioned

I converted our MC WFS relief from CSH to BASH today. I also added 'wait' commands and 'echo' commands so that all DoFs run in parallel nicely. It can be accessed from the MC WFS screen.

I increased the overall MC WFS gain input slider from 0.02 to 0.1 (its in the mcwfson script). The MC Trans loops now have a time constant of ~30 seconds. The relief script relieves ~90% of the MC WFS control signals in the 2 minutes that its allowed to run.

On the next upgrade, we should make it python and have it kill the relief process if the MC loses lock before relief is applied via the alignment sliders.

Attachment 1: WFSrelief.png
  11584   Wed Sep 9 11:00:49 2015 IgnacioUpdateIOOLast Wiener MCL subtractions

On Thursday night (sorry for the late elog) I decided to give the MCL FF one more try. 

I first remeasured the actuator transfer function because previous measurements had poor coherence ~0.5 - 0.7  at 3 Hz. I did a sine swept to measure the TF. 

Raw transfer function:

The data is attached here: TF.zip

Then I made Wiener filters by fitting the transfer function data with coherence > 0.95 (on the left). Fitting all the data (on the right). Here are the filters:


The offline subtractions (high coh fit on left, all data fit on right). Notice the better IIR performance when all the TF data was fitted.


The online results: (these were aquired by taking five DTT measurements with 15 averages each and then taking the mean of these measurements)


And the subtraction performance:


Attachment 3: TF.zip
  11585   Wed Sep 9 11:33:58 2015 ranaUpdateSummary PagesSummary Page updates
  • Made most plots in IOO tab only plot when MC_TRANS > 10000 using Eve's MC_LOCK state definition.
  • added the 0.03 - 0.1 Hz and 10-30 Hz bands to the PEM SEIS BLRMS tab and set the y-scales to the same as SeismicRainbowSTS.stp
  • set state PMC_LOCK in PSL tab and made some of those plots only plot when PMC trans > 0.6.
  • SUS-OL page showed me that the ETM yaw spectrum was wacky, which lead me to find that it was completely uncentered. Stop leaving the room lights ON Steve!!  angry I also set the quadrant offsets by blocking the QPD with a piece of metal (teflon doesn't work).
  • set c1summary to only plot some when X or Y arms are locked
  11587   Wed Sep 9 15:45:11 2015 ericqUpdatePEMInverted STS filters in C1OAF

Our online subtraction filters for PRC angle and MC length were trained on the raw ADC signals, so I've inverted the filters that Rana installed in the PEM filter banks in the OAF signal conditioning filter banks (C1:OAF-WIT_STS1X, etc.)

It's not perfect, since the inversion would be unstable, and thus needs a low pass. I used an ELP at 800Hz. The error in the inversion is then something like half a degree at 5Hz, which is the highest frequency we really ever subtract at. It should be ok.

  11588   Thu Sep 10 01:09:20 2015 ranaUpdateLSCMoved LSC sensing matrix notch frequencies

We looked at the DRMI noise spectrum and chose new excitation frequencies such that the lines are lower in frequency than before (~300 Hz instead of 800 Hz) and also not in some noisy region.

New filters is saved and loaded for all LSC DOFs.

Attachment 1: NewLSCnotches.png
  11589   Thu Sep 10 04:23:00 2015 ericqUpdateLSCMoved LSC sensing matrix notch frequencies

Frequencies are:

  • CARM: 309.21 Hz
  • DARM: 307.88 Hz
  • MICH: 311.1 Hz
  • PRCL: 313.31 Hz
  • SRCL: 315.17 Hz

POP110 and POP22 demod angles were adjusted for DRMI lock. 

Last week, I never achieved a fully 1F lock, REFL165 was used for SRCL. Tonight, we created input matrix settings for pure 1F locking, and did some signal mixing to reduce the PRCL to SRCL coupling. The PRCL to MICH coupling was already low, since AS55 is fairly insensitive to PRCL. 

Similarly, for the 3F signals, some signal mixing of REFL33I and REFL165Q was used to reduce the PRCL to MICH coupling. The PRCL to SRCL coupling in REFL165 isn't too bad, so no compensation was done. Interestingly, in this setting, the 3F MICH and SRCL signals agree with the 1F signals on their zero crossing, so no offsets are needed. REFL33 I does need an offset, however, to match the REFL11I PRCL zero crossing. 

The DRMI acquires faster with SRCL set to 165I. Once acquired, the 1F/3F can be made smoothly, and both settings are very stable. The sensing matrix in each setting is consistent with each other. (The PRCL and SRCL lines in AS55 change, but really I shouldn't even plot them, since they're not very coherent). 

For some reason, these show a sign flip relative to last week's measurements. The relative angles are consistent, though. 

Next up is finding the right coefficient for the SRM in the MICH output matrix, when actuating on the BS. 

Attachment 1: DRMI_1F.pdf
Attachment 2: DRMI_3F.pdf
  11591   Fri Sep 11 10:56:47 2015 SteveUpdateendtable upgradeETMY optical table feedthrough

The ETMY enclosure feedthrough - north is installed. The sealing material is hard to work with.

The upper empty blocks will be replaced by something soft to make changing cables easy.


Attachment 1: ETMY-Nfeedt.jpg
  11592   Sun Sep 13 13:26:00 2015 ranaUpdateIOOLast Wiener MCL subtractions

When making the Wiener filter OFF/ON comparisons, we want to use the median PSD estimates, not the mean (which is what pwelch gives you).

cf. Sujan's note and Evan's follow-up

The median will be less sensitive to the transients / gltiches and will show more improvement I think.

  11593   Mon Sep 14 10:41:03 2015 SteveUpdateVACTP2 dry pump replaced

TP2 dry fore pump sn PLE10082 was replaced at pressure 717 mTorr,  TP2 50K rpm 0.33A @ 112,677 hrs

Top seal life was 8,160 hrs

Model  SH110, Sn LP1007L556 was installed. It's fore line pressure after 30 minutes of running 38 mTorr, TP2 turbo at 50K rpm 0.18A



Attachment 1: TP2_dry_pump_replaced.png
  11594   Mon Sep 14 16:50:12 2015 ericqUpdateLSCQuick note

Just a heads up while I'm out for a bit: the delay line is currently installed in the 55MHz modulation path. 

I'll be back later, and will revert the setup.

  11595   Mon Sep 14 21:42:00 2015 ranaUpdateIOOMC Wiener + Summary

I turned on the MCF FF in the OAF today (we need to fix the labeling of the 'ON' buttons on the RHS of the screen). The performance is still good; before / after attached.

Not only is the 1 Hz performance in the MC still good, but the X & Y arm noise reduction is ~1 order of magnitude. Good to know that the filters aren't changing much with time.

Can we just leave this on all the time now? Seems to be OK and there's no visible increase in the arm noise with this on.

Also did some updates to the summary pages and added a CDS FEC tab for CPU times.

Please take a look at the summary pages and bring a list of demands to the Wednesday meeting.

Attachment 1: mcf.pdf
  11596   Mon Sep 14 23:12:49 2015 ericqUpdateLSC55MHz modulation phase effect on PRMI

With the adjustable delay line box installed in the 55MHz modulation path, I've measured the PRMI sensing matrix as a function of delay / relative phase between the 11MHz and 55MHz modulations. The relative frequency difference of 44MHz tells us that this should be cyclical after ~23nsec of delay, but losses in the delay cable change this; see Koji's elogs about the modulation cancellation setup for details. 

TL;DR: Nothing really changes, other than REFL33 optical gain. MICH/PRCL angles remain degenerate.

The results aren't so surprising. The demod angles for the 55MHz diodes don't even change, since the same 55MHz signal is used for the modulator and demodulators, so delaying it before the split should go unnoticed. Most of these measurements were made during the same lock stretch, PRCL on REFL11 I and MICH on AS55Q.

The only signals we would expect to change much are ones that have significant contriubtions from field products influenced by both modulations. None of the 1F PDs are like this, nor is REFL165. REFL33 is the odd man out, where the +44MHz field produced as a -11MHz sideband on the +55MHz sideband beats with the +11MHz sideband (and the same with the signs flipped). I made a simulation for the 40m poster at the March 2015 LVC meeting, but I don't think it ever made it to the ELOG. 


Here are the results for the 0ns and 4ns cases, as an illustration of what changes (REFL33), and what doesn't (everything else). Again, these are calibrated to Volts out of the analog demod boards per meter of DoF motion. 


So, since REFL33 is the only one really changing, let's just look at it by itself:

Qualitatively, the change in magnitude looks similar to the simulation result. The demod angles fall by some roughly linear amount. The angle difference is even more stationary than predicted there, though. 

Attachment 1: PRMI_CAR_0ns.pdf
Attachment 2: PRMI_CAR_4ns.pdf
Attachment 3: delaySweep_nominal.pdf
Attachment 4: 55delay_PRMI_REFL33.pdf
  11600   Tue Sep 15 16:49:08 2015 SteveUpdateendtable upgradeETMY optical table feedthrough

ETMY optical table enclosure feedthrough- south is in. Now it is time to see how air tightness increases performance.


The ETMY enclosure feedthrough - north is installed. The sealing material is hard to work with.

The upper empty blocks will be replaced by something soft to make changing cables easy.



Attachment 1: ETMYsFeedt.jpg
  11605   Wed Sep 16 03:44:18 2015 KojiUpdateLSCRF micky mouse

1. POP110 RF amps are powered from the cross connect. But that +15V block has GND connections that are not connected to the ground.
    i.e. The ground potential is given by the signal ground. (Attachment 1)

    This is caused by the misuse of the DIN connector  blocks. The hod side uses an isolated block assuming a fuse is inserted.
    However, the ground sides also have the isolated blocks

2. One of the POP110 RF cable has a suspicious shiled. The rigidity of the cable is low, suggesting the broken shield. (Attachment 2)

Attachment 1: IMG_20150915_231038191.jpg
Attachment 2: IMG_20150915_234257144.jpg
  11607   Wed Sep 16 23:07:06 2015 ranaUpdateElectronicsLSC Whitening board: LP filters added, pictures taken

I added the 0.1 uF and 47 nF caps that I mentioned so that we can now bypass the AA filters for these channels. (mistakenly installed 47 instead of 0.47 nF on the first round and we got 350 Hz poles instead of 35 kHz)

Gautam and I checked out the AA sit and it seems that the XYCOM-220 cable which ought to allow switching of the AA filter is not connected on the XYCOM side, so the LSC AA filters are always ON. In order to bypass them, we'll need to just short the bypass control pins or just set the +5V on the board to GND, by lifting the EMI3 filter and shorting C6.

I have so far only made the changes on s/n 115 (used for AS55, REFL55, and REFL165), other 2 boards to follow soon.

Before making the AA change, we want to measure the HF spectrum the ADC for each of our main signals in the PRFPMI state. In lieu of that, we'll measure the spectrum at the I/Q mon ports of the demod boards via SR785 and then use matlab to propagate the signals to the ADC to make our estimate of how much anti-aliasing we need.

Changes relative to D990694-B:

  1. R215, R216, R217, R218, R219: 4.75k -> 9.53k.  This change was made long to make the DC gain of channels 4-8 be unity, the same as channels 1-3.
  2. 0.1 uF NPO cap in parallel with R127, R128, R129, R130, R131, R132, R133, R134.
  3. R127, R128, R129, R130, R131, R132, R133, R134 all 100k (was already like this) to keep LT1128 from floating up when input cables are disconnected.
  4. C158, C159, C160, C161, C162, C163, C164, C165, C166, C167, C168, C169, C170, C171, C172, C173, all were empty, now are 0.47 nF NPO.

I also looked at the noise in a few different configurations to see what we ought to do next.

BLACK: AS55I_IN1 with 0 dB whitening gain and whitening filter OFF, so its all just ADC noise

RED: same but with +45 dB whitening gain and WF ON, so above 10 Hz this is now the noise of the PD / demod chain

BLUE: RED w/ the anti-WF applied

PURPLE: in-loop POX11_I spectrum with x-arm locked

The conversion from counts to volts 0.0006, so the black trace is ~5 uV/rHz as expected. Its clear that we would be sort of OK for most of our channels if we just had 1 stage of whitening. I think we ought to convert the input stage into a 100:20 stage and also change the other whitenings into a 100:20 instead of 150:15. Then we'll have less gain at 15 Hz, but more at 100 Hz.

We really need to buy some surface mount capacitors, Steve - we ought to have at least 100 of all the ones in that little gray cabinet.

Attachment 1: 20150916_221210.jpg
Attachment 2: out.pdf
  11608   Thu Sep 17 02:22:53 2015 SteveUpdateendtable upgradeETMY optical table feedthrough

I doubt we'll see any effect until we carefully seal the holes. If there's 1 hole in your boat it still sinks.


ETMY optical table enclosure feedthrough- south is in. Now it is time to see how air tightness increases performance.


  11610   Thu Sep 17 08:36:14 2015 SteveUpdatePEMearth quake

No damage. The BS sensor UR 0.220 V has been low for some times.

Dataviewer does not work for long term trend.

Attachment 1: Chilian_eq_8.3M.png
Attachment 2: BS_UR_0.220V.png
Attachment 3: LowSensingV_BS-UR.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.


  11613   Thu Sep 17 17:27:01 2015 gautamUpdateLSCRF micky mouse - dodgy DIN connector blocks fixed

[Steve, gautam]

We fixed the problematic DIN connectors on 1Y2, by swapping out the 3 DIN connector blocks that were of the wrong type (see attached image for the difference between the types appropriate for "Live" and "Ground").

Before doing anything, Eric turned the Wenzel multiplier off. We have not turned this back on.

Then we turned off the power supply unit at the base of 1Y2, removed the connectors from the rail, swapped out the connectors, reinstalled them on the rail, and turned the power supply back on. After swapping these out, we verified with a multimeter that between each pair of "Live" and "Ground" blocks, there was ~15V. We could now use the third unused pair of blocks to power the delay line phase shifter box, though for the moment, it remains powered by the bench power supply. 


1. POP110 RF amps are powered from the cross connect. But that +15V block has GND connections that are not connected to the ground.
    i.e. The ground potential is given by the signal ground. (Attachment 1)

    This is caused by the misuse of the DIN connector  blocks. The hod side uses an isolated block assuming a fuse is inserted.
    However, the ground sides also have the isolated blocks

2. One of the POP110 RF cable has a suspicious shiled. The rigidity of the cable is low, suggesting the broken shield. (Attachment 2)


Attachment 1: DIN_rail_terminal.jpg
  11614   Thu Sep 17 19:42:43 2015 KojiUpdateLSCRF micky mouse - dodgy DIN connector blocks fixed

1. The delay-line box is now hooked up to the cross connect +15V supply.

2. The broken RF cable was fixed.

It is actually the POP22 cable.
Therefore, we might see significant change of the signal size for POP22.
Be aware.

RG405 + SMA connector rule

- Don't bend the cable at the connector.

- Always use a cap on the connector. It is a part of the impedance matching.

- Use transparent shrink tube for strain relieving and isolation. This allow us to check the condition of the shield without removing the cover.

Attachment 1: IMG_20150917_190635033.jpg
Attachment 2: IMG_20150917_192551919.jpg
  11616   Fri Sep 18 08:03:53 2015 ranaUpdateLSCRF micky mouse - dodgy DIN connector blocks fixed

Steve and I turned on the box this morning so that the IMC would lock again.

For future reference, remember that one should turn off the Marconi output before turning off the RF distribution box. Don't drive the input of unpowered RF amps.


  11617   Fri Sep 18 08:04:09 2015 ranaUpdateLSCRF micky mouse - dodgy DIN connector blocks fixed

Steve and I turned on the box this morning so that the IMC would lock again.

For future reference, remember that one should turn off the Marconi output before turning off the RF distribution box. Don't drive the input of unpowered RF amps.


  11619   Fri Sep 18 11:59:08 2015 ericqUpdateLSCAUX X Laser Current Reverted

Once again, the transmitted X green beam was showing enormous intensity fluctuations (50x higher than normal). Last month, I reduced the AUX X laser current from 2.0A to 1.9A, which I thought had fixed it somehow.

However, when I sent to the end to check it out today, I found the SR560 which is there to amplify the green PDH error signal before being sent to the AA board was overloading. Not so surprising, since the error signal was similarly noisy as the transmitted light. 

I turned the SR560 gain down, and, after relocking, the transmitted light was stable. I've turned the AUX X laser current back up to 2.0A, it's previous nominal value, and the green transmitted light is still stable. 

I'm a little mystified that the 560 could intefere with the loop, since it is not in the feedback path. Could it be that when it is overloading, it sends garbage backwards out of the inputs? But even then, its input is not connected to the real error point, but the buffered monitor port. Could it be interfering via the power line?

Before, I had hesitated adding gain to the PDH board's monitor point for DAQ purposes, because the motivation of the port is to provide a 1:1 version of the real error signal, and I didn't want to add gain to the AA board, because we normally don't have gain in those boards, and I didn't want to surprise future people. The SR560 was meant to be temporary, but as often happens, it was forgotten. Now, I think I will add gain to the error monitor buffer stage of the PDH boards. 

  11620   Fri Sep 18 13:33:17 2015 ericqUpdateLSCFast ALS troubles - Noise at 36kHz

To get around the problems between the pomona LPF and low CM board input impedance, I've placed the LPF at the CM board fast output. This won't work as a permanent solution, since we only want to lowpass the ALS signal, but it should be fine for a single arm test. 

However, I kept getting blown out of lock when turning up the AO gain, but well before I really expect any real action from the fast path. Looking at the OLTF, I was seeing some large spike at ~36kHz nearing 0dB loop gain with unstable phase. This prompted me to look at the ALS error signal out to higher bandwidth with the SR785; before I only ever looked at it through the digital system. 

So, with the X arm locked via POX11 I, and ITMY misaligned to use AS55 as an out of loop sensor, I measured the spectrum of the I ouput of the ALS X demod board (which was set to be near a zero crossing via the delay line), and the Q Mon of the AS55 demod board. 

Both ALS and AS55 show a sharp line at around 36.5kHz, so something is really happening in the IFO at this frequency. Koji might have seen an indication of this back in March.

What's going on here? And what would be different about PRFPMI that wouldn't have made this a problem for locking?

Attachment 1: IRlock_noises.pdf
  11621   Fri Sep 18 16:08:41 2015 ericqUpdateLSCFast ALS troubles - Noise at 36kHz

 I looked at REFL11 and REFL55 during PRMI lock - the line is there.

In fact, it is even visible in REFL11 I from a single bounce off of the PRM (ITMs misaligned).

This led me to look at the IMC error point (via the OUT2 on the servo board, no compensation for the input gain). Also there!

Attachment 1: PRMIlock_REFLspectra.pdf
Attachment 2: IMCspectrum.pdf
  11622   Fri Sep 18 19:15:35 2015 ranaUpdateLSCFast ALS troubles - Noise at 36kHz

One the Wiki (https://wiki-40m.ligo.caltech.edu/40mHomePage), we have a Mech Resonance page for mechanical frequencies and a PEM page where we want to list the sources of all of our environmental lines. So please put in an entry when you find out what's at this frequency. This reminds me that I need to upload my MC2 COMSOL eigenmode analysis.

  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.

  11625   Mon Sep 21 11:12:14 2015 SteveUpdateVACcold cathode is flaky

CC4 cold cathode gauge jump triggered interlock to close VM1 valve to protect the RGA.

The IFO pressure is 1e-5 Torr

Vac normal was recovered by opening VM1


Attachment 1: cc4jumps.png
  11626   Mon Sep 21 11:40:30 2015 ericqUpdateGeneralMegatron maitenence

The MC autolocker and FSSslow scripts weren't running on Megtron. These were started by running the following commands on megatron:

sudo initctl start MCautolocker
sudo initctl start FSSslow

The new autoburt cronjob was failing because the .cron file was not executable (fixed by chmod +x burtnew.cron), and the new perl script didn't use the full path for ifconfig. Similarly, the simulink webview updating script was failing because the full path for matlab wasn't being given. Both of these fixes have been tested and commited to SVN. 

In general, cron scripts can be a real pain, since the cron process doesn't run our .bashrc, and so doesn't know about updates to $PATH, or other environment vairables that get updated through /ligo/cdscfg/workstationrc.sh, which is called by .bashrc. So something that manually works fine in the terminal may not play out as expected when run by cron.

  11627   Mon Sep 21 15:22:19 2015 jamieUpdateDAQworking on new fb replacement

I've been putting together a new machine that Rolf got for us as a replacement for fb.

I've installed and configured the OS, and compiled daqd and the necessary supporting software.  I want to try acquiring data with it.  This will require removing the current/old fb from the DAQ network, and adding the new machine.  It should be able to be done relatively non-invasively, such that none of the front end configuration needs to be adjusted, and the old fb can be put back in place easily.

If the test is successfully, then I'll push ahead with the rest of the replacement (such as either moving or copying the /frames RAID to the new machine).

I will do this work in the early AM tomorrow, September 22, 2015.

  11632   Tue Sep 22 03:48:18 2015 ericqUpdateLSCDRMI tweaked, briefly held with ALS arms

Given the RF component power supply grounding, POP110, POP22 and REFL165 all changed somewhat. They have all been rephased for the DRMI, as they were before. 

I tweaked the 3F DRMI settings, and chose to phase REFL165I to PRCL, instead of SRCL as before, to try and minimize the PRCL->MICH coupling instead of the SRCL->MICH coupling. 

With these settings, I once locked the DRMI for ~5 seconds with the arms held off on ALS, during which I could see some indications of neccesary demod angle changes. Haven't yet gotten longer, but we're getting there...

  11633   Tue Sep 22 08:58:38 2015 SteveUpdateVACcold cathode is flaky

The cold cathode gauge is back to normal. cc4 is the last gauge is "functioning"

MKS is not responding. The spare controller and gauges are back for repair.


Attachment 1: 4and80days.png
  11634   Tue Sep 22 16:42:39 2015 ericqUpdateIOOHousekeeping

I've moved the OAF MC2 signal path to go directly from c1oaf to c1mcs, so that the LSC being ON/OFF doesn't interfere with the MC length seismic feedforward. Since the FB is currently down, I can't do a full test, but looking at monitor points in StripTool indicates it's working as intended. 

I also cleaned up some LSC medm stuff; exposing the existing SRCL UGF servo, and removing a misleading arrow. This reminds me that I need to get calibration lockins back up and running...

  11636   Tue Sep 22 17:30:55 2015 jamieUpdateDAQattempts at getting new fb working

Today I've been trying to get the new frame builder, tentatively 'fb1', to work.  It's not fully working yet, so I'm about to revert the system back to using 'fb'.  The switch-over process is annoying, since our one myrinet card has to be moved between the hosts.

A brief update on the process so far:

I'm being a little bold with this system by trying to build daqd against more system libraries, instead of the manually installed stuff usually nominally required.  Here's some of the relevant info about th fb1 system:

  • Debian 7 (wheezy)
  • lscsoft ldas-tools-framecpp-dev 2.4.1-1+deb7u0
  • lscsoft gds-dev 2.17.2-2+deb7u0
  • lscsoft libmetaio-dev 8.4.0-1+deb7u0
  • lscsoft libframe-dev 8.20-1+deb7u0
  • /opt/rtapps/epics-
  • /opt/mx-1.2.16
  • advLigoRTS trunk

I finally managed to get daqd to build against the advLigoRTS trunk (post 2.9 branch).  I'll post detailed build log once I work out all the kinks.  It runs ok, including writing out full frames, as well as second and minute trends and raw minute trends, but there are a couple of show-stopper problems:

  • daqd segfaults if the C1EDCU.ini is specified.  If I comment out that one file from the 'master' channel ini file list then it runs without segfaulting.
  • Something is going on with the mx_streams from the front ends:
    • They appear to look ok from the daqd side, but the FEC-<ID>_FB_NET_STATUS indicators remain red.  The "DAQ" bit in the STATE_WORD is also red.  Again, this is even though data seems to be flowing.
    • The mx_stream processes on the front ends are dying (and restarting via monit) about every 2 minutes.  It's unclear what exactly is happening, but they all dia around the same time, so it possibly initiated from a daqd problem.  Around the time of the mx_stream failures, we see this in the daqd log:
[Tue Sep 22 17:24:07 2015] GPS MISS dcu 91 (TST); dcu_gps=1127003062 gps=1127003063

Aborted 1 send requests due to remote peer Aborted 1 send requests due to remote peer 00:25:90:0d:75:bb (c1sus:0) disconnected
mx_wait failed in rcvr eid=004, reqn=11; wait did not complete; status code is Remote endpoint is closed
00:30:48:d6:11:17 (c1iscey:0) disconnected
mx_wait failed in rcvr eid=002, reqn=235; wait did not complete; status code is Remote endpoint is closed
disconnected from the sender on endpoint 002
mx_wait failed in rcvr eid=005, reqn=253; wait did not complete; status code is Bad session (missing mx_connect?)
disconnected from the sender on endpoint 005
disconnected from the sender on endpoint 004
[Tue Sep 22 17:24:13 2015] GPS MISS dcu 39 (PEM); dcu_gps=1127003062 gps=1127003069
  • Occaissionally the daqd process dies when the front end mx_streams processes die.

I'll keep investigating, hopefully with some feedback from Keith and Rolf tomorrow.

  11637   Wed Sep 23 03:08:50 2015 ericqUpdateLSCDRMI + ALS Arms

[ericq, Gautam]

We can reliably lock the DRMI with the arms held off on ALS. yes

I have not been able to hold it at zero CARM offset; but this is probably just a matter of setting up the right loop shapes with enough phase margin to handle the CARM fluctuations ( or figuring out high bandwidth ALS...)

Right now, it's the most stable at CARM offsets larger (in magnitude) than -1. Positive CARM offsets don't work well for some reason. 

The key to getting this to work was to futz around, starting from the misaligned arms DRMI settings, until brief locks were seen (triggering all 3 DRMI DoFs on POP22, since the correct AS110 sign was amiguous). I could tell from how the control signals responded to gain changes that REFL165Q, which was being used as the MICH error signal, was seeing significant cross coupling from both PRCL and SRCL, suggesting the demod angle of REFL165 had to be adjusted. I randomly tweaked the REFL165 demod angle until a 20 second lock was achieved, with excitations running. Then, I downloaded that data and analyzed the sensing matrix. This showed me that the REFL33 demod angle was ok, and the PRCL-from-SRCL subtraction factor determined with the arms misaligned was still valid. The main difference was indeed the SRCL angle in REFL165.

With the REFL165 demod angle properly adjusted, the DRMI would briefly lock, but the DRMI had become somewhat misaligned at this point, and the SRC could be seen to mode hop. Interestingly, the higer order modes had an opposite sign in AS110, with respect to the TM00. At that point, I went back to PRMI on carrier to dither-align the BS and PRM. 

With alignment set, the DRMI would lock on TM00 readily, still only triggering on POP22. I set the AS110 angle, and moved SRCL triggering over to that, which sped up acquisition even more. The input matrix and FM gains from no-arms DRMI still work for acquistion; UGF servos were used to adjust overall gains a bit. 

At CARM offsets larger in magnitude than -1, the DRMI lock seems indefinite. I just broke it to see how fast it would acquire; 3 seconds. cool

Lastly, here is the sensing matrix at CARM offset of -4, measured over five minutes. REFL11 is the only degenerate looking PD. Thus, I feel like controlling the DRMI of the DRFPMI should be more managable than I had feared.

(I didn't include/excite CARM or DARM, because I'm not sure it would really mean anything at such a large CARM offset)

Attachment 1: DRMIarms.pdf
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