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ID Date Author Type Category Subject
  11487   Mon Aug 10 15:25:05 2015 SteveUpdatePEMwasp nest

The wasp nest will be removed tomorrow from from the out side of the east arm window.

The resonant frequency of the newly arrived gravity bee detector is not known.
 

Attachment 1: waspN.jpg
waspN.jpg
  11486   Mon Aug 10 11:57:45 2015 ericqUpdateGeneralIMC work
Quote:

Often when I come to manually lock the mode cleaner due to a long unlocked period, I find that the sliders are not in the state specified by the mcdown script. Furthermore, it's not the same channels every time; sometimes the servo gain is left high, sometimes the boosts are left on. I fear that some of the caput commands are failing to execute. Ugh. 

This continues to happen. I believe the network latency boogeyman is to blame. 

There was a long unlocked period because the enable switch for the MC servo fast path (FASTSW) was left off. Running the mcdown script fixed this, but included the error message:

Channel connect timed out: 'C1:IOO-MC_REFL_GAIN' not found.
CA Client Library: Ignored duplicate create channel response from CA server?

which means the IN1 gain didn't get touched. A second pass of the script produced no errors. 

I'm thinking of adding some logic that if the autolocker has failed to lock for some period (5 minutes?), it should rerun mcdown. 

  11485   Thu Aug 6 21:03:45 2015 IgnacioHowToWienerFilteringHow to do online static IIR Wiener filtering

In order to do online static IIR Wiener filtering one needs to do the following,

1) Get data for FIR Wiener filter witnesses and target.

2) Measure the transfer function (needs to be highly coherent, ~ 0.95 for all points) from the actuactor to the control signal of interest (ie. from MC2_OUT to MC_L).

3) Invert the actuator transfer function.

4) Use Vectfit or (LISO) to find a ZPK model for the actuator transfer and inverse transfer functions.

5) Prefilter your witness data with the actuator transfer function, to take into account the actuator to control transfer function when designing the offline Wiener FIR filter.

6) Calculate the frequency response for each witness from the FIR coefficients.

7) Vectfit the frequency reponses to a ZPK model, this is the FIR to IIR Wiener conversion step.

8) Now, either, divide the IIR transfer function by the actuator transfer function or more preferably, multiply by the inverse transfer function.

9) Use Quack to make SOS model of the IIR Wiener filter and inverse transfer function product that goes into foton for online implementation.

10) Load it into the system.

The block diagram below summarizes the steps above.

Attachment 1: iir.png
iir.png
  11484   Thu Aug 6 11:45:01 2015 JessicaUpdateGeneralALS Delay Line front panel testing

Koji had suggested that I sync up the two function generators to ensure that they have the same base frequency and so that crosstalk will actually appear at the expected frequency. After syncing up the two function generators, I drove the following frequencies through each cable:

Conductive SMAs:

     X: 29.537 MHz           Y: 29.5372 MHz

Isolated SMAs:

     X: 29.545 MHz           Y: 29.5452 MHz

Each time, the difference between the frequencies was 200 Hz, so if there was crosstalk, a spike should appear in the PSDs at 200 Hz when frequencies are being driven through both cables simulataneously, but not when just one is on. We very clearly see a spike at 200 Hz in both the X arm and the Y arm with the conductive SMAs, indicating crosstalk. For the front panel with isolated SMAs, we see a spike at 200 Hz when both frequencies are on, but it is much less pronounced than with the conductive SMAs. It seems as though there will be crosstalk using either panel, just less with the isolated SMAs. 

Attachment 1: conductive_X.png
conductive_X.png
Attachment 2: conductive_Y.png
conductive_Y.png
Attachment 3: isolated_X.png
isolated_X.png
Attachment 4: isolated_Y.png
isolated_Y.png
  11483   Thu Aug 6 09:16:57 2015 SteveUpdateVACChiara gets new Ethernet card
  1. Yesterday we did put the vacuum system into safe to reboot mode  for the ethernet card swap.
  2. Atm1, IFO pressure
  3. Atm2, as prepared valve configuration where " moving " means closed and disconnected

 

Attachment 1: ChiaraNetCard.png
ChiaraNetCard.png
Attachment 2: 23.png
23.png
  11482   Thu Aug 6 04:36:41 2015 ericqUpdateASCReviving PRC angular feedforward

Tonight, I've taken a bunch of data where the PRC is carrier locked and the ITM oplevs have the DC coupling FM turned on, as we use during locking. This is to inform new feedforward filters to stabilize the PRC angular motion, by using Wiener filtering with the POP QPD as the target, and local seismometers/accelerometers as witnesses. So far I've looked at the 1800 seconds leading up to GPS time 1122885600, but there has been plenty of locked time tonight if I need to retrieve more. 

I've also measured the PRM ASC output torque -> POP QPD spot motion with high (>0.95) coherence from 0.1Hz to 10Hz. 

Prefiltering so far consists of a 4th order elliptic LP at 5 Hz, with the target subtraction band being the 1-3Hz range. 

With offline FIR filtering, the RMS pitch motion is reduced by a factor of 3 just with the STS1_X data. IIR fitting remains to be done. 

The PRC yaw motion, which is marginally noisier, is a little more tangled up across X and Y. 

Plots / filters forthcoming pending more analysis. 

  11481   Thu Aug 6 01:38:19 2015 ericqUpdateComputer Scripts / ProgramsChiara gets new Ethernet card

Since Chiara's onboard ethernet card has a reputation to be flaky in Linux, Koji suggested we could just buy a new ethernet card and throw it in there, since they're cheap. 

I've installed a Intel EXPI9301CT ethernet card in Chiara, which detected it without problems. I changed over the network settings in /etc/networking/interfaces to use eth1 instead of eth0, restarted nfs and bind9, and everything looked fine. 

Sadly, EPICS/network slowdowns are still happening. :(

  11480   Wed Aug 5 17:15:08 2015 EveUpdateSummary PagesFixed ASC Tab

I've fixed the ASC tab on the summary pages to populate the graphs with data without causing an error.

Motivation: The ASC tab was showing no data. It resulted in a name error when generated.

What I did:

A name error indicates a bad channel name in the plot definition. I identified two errors in the code:

  1. I said C1:SUS_MC1_ASCPIT_OUT16.mean instead of C1:SUS-MC1_ASCPIT_OUT16.mean (underscore should be dash)
  2. The channel C1:ASX-XARM_M1_PUT_OSC_CLKGAIN was resulting in a name error. I removed it.

Results:

The plots are not processing without error. However, no titles or axis labels are present on the plots- I'll work on adding these.

 

  11479   Wed Aug 5 10:56:07 2015 ericqUpdateCDSMany models crashed

Last night around 1AM, many of the the frontend models crashed due to an ADC timeout. (But none of the IOPs, and all the c1lsc models were fine.)

 
First, on c1sus (Wed Aug  5 00:56:46 PDT 2015)
[1502036.695639] c1rfm: ADC TIMEOUT 0 46281 9 46153
[1502036.945259] c1pem: ADC TIMEOUT 0 56631 55 56695
[1502036.965969] c1mcs: ADC TIMEOUT 1 56706 2 56770
[1502036.965971] c1sus: ADC TIMEOUT 1 56706 2 56770

Then, simultaneously on c1ioo, c1iscex, and c1iscey. (Wed Aug  5 01:10:53 PDT 2015)

[1509007.391124] c1ioo: ADC TIMEOUT 0 46329 57 46201
[1509007.702792] c1als: ADC TIMEOUT 1 63128 24 63192

[2448096.252002] c1scx: ADC TIMEOUT 0 46293 21 46165
[2448096.258001] c1asx: ADC TIMEOUT 0 46669 13 46541

[1674945.583003] c1scy: ADC TIMEOUT 0 46297 25 46169
[1674945.685002] c1tst: ADC TIMEOUT 0 52993 1 52865

I'm still working on getting things back up and running. Just restarting models wasn't working, so I'm trying some soft reboots...


UPDATE: A soft reboot of all frontends seems to have worked,

Attachment 1: crashes.png
crashes.png
  11478   Tue Aug 4 03:02:30 2015 ericqUpdateLSCBeat note Alignment fluctuation effects measured

Notes from tonight's work:

  • PMC alignment tweaked. Not much gained
  • WFS/MC2 offsets tweaked after recentering beams on WFS and some hand alignment. 
  • Vertex oplevs realigned for the first time in forever
  • With an RF coupler, measured the X green beatnote to be +5dBm into the splitter. This resulted in -33dBm at the control room analyzer. 
  • Switched the ALS demod board inputs, from piping the delayed signal to the RF input, to sendingit to the LO input. This was motivated by wanting the mixer closer to compression, hopefully to reduce beatnote amplitude fluctuation sensitivity. This won some noise >100Hz.
    • This led to record ALS noise levels - X:217Hz, Y:203Hz yes
    • +2dBm into the board still leaves us some headroom for futher amplification. Board schematic lists +10dBm LO as "nominal," but maybe this isn't worth it... 
  • PRFPMI locking is still stalled at bringing in the RF signals. Debugging continues.
  • Some beatnote amplitude fluctuation investigations (see below)
  • Note to self: demod board schematics include an unspecified RF lowpass. Check out what got stuffed in there. 


I've explored the beatnote fluctuations a bit further. 

First, I realized that we already had a channel than functions much like an RF level monitor: the phase tracker Q output. I verified that indeed, the Q signal agrees with the RF monitor signals from the demod board within the phase tracker bandwidth. This simplifies things a little.

I also found that the Y beat suffers a fair bit less from these effects; which isn't too surprising given our experience with the alignment stability.


One possible caveat to my earlier conclusions is that the beatnote amplitude could be fluctuating due to real RIN of the green light transmitted through the cavity. In fact, this effect is indeed present, but can't explain all of the coherence. If it did, we would expect the DC green PDs (ALS-TR[X/Y]) to show the same coherence profile as the RF monitors, which they don't.  


The next thing I was interested was whether the noise level predicted via coherence was realistic. 

To this end, I implemented a least-squares subtraction of the RF level signal from the phase tracker output. I included a quadratic term of the RF power, but this turned out to be insiginficant. 

Indeed, using the right gain, it is possible to subtract some noise, reproducing nearly the same spectrum as the coherence based estimate. The discrepency at 1Hz is possible from 1Hz cavity RIN, as suggested by the presence of some coherence with TRX. 

However, this is actually kind of weird. In reality, I would've expected the coupling of RF level fluctuations to be more like a bilinear coupling; changing the gain of the mixer, rather than directly introducing a linearly added noise component. Maybe I just discovered the linear part, and the bilinear coupling is the left over low frequency noise... I need to think this over a little more.  

Attachment 1: coherences.png
coherences.png
Attachment 2: linX.png
linX.png
  11477   Mon Aug 3 18:19:09 2015 JessicaUpdateGeneralAnodization of front panels accounted for

Previously, I had gotten the same results for the conductive and the isolated front panels. Today, I sanded off the anodized part on the back of the conductive front panel. I checked afterwards with a mulitmeter to ensure that it was indeed conductive through all the SMA connectors. 

I drove a frequency of 29.359 Hz through the X Arm cable and 29.3592 Hz through the Y Arm cable, giving a difference of 200 Hz. Previously, there would only be a spike in the Y Arm at the difference, while the X Arm did not change if the Y arm was on or off. Now that the panel is fully conductive, a spike can also be seen in the X arm, indicating that crosstalk may possibly be happening with this panel, now that the spike corresponds to both the X arm and Y arm. These results are only after one set of data. Tomorrow I'll take two more sets of data with this panel and do a more in depth comparison of these results to what had been previously seen.  

Attachment 1: redo_conduct1X.png
redo_conduct1X.png
Attachment 2: redo_conduct1Y.png
redo_conduct1Y.png
  11476   Mon Aug 3 08:16:19 2015 SteveUpdateSUSETMX damping restored
Attachment 1: ETMXrestored.png
ETMXrestored.png
  11475   Sat Aug 1 20:46:29 2015 KojiUpdatePEMX seismo station short cable removed

OMG

  11474   Sat Aug 1 17:04:29 2015 EveUpdateSummary PagesStates and Triggers in SPs

I've added states to the summary pages to only show data for times at which one certain channel is above a specified threshold. So far, I've incorporated states for the IOO tab to show when the mode cleaner is locked.

You can see these changes implemented in the IOO tab of my personal summary pages for June 30: https://ldas-jobs.ligo.caltech.edu/~eve.chase/summary/day/20150630/ioo/.

I've written a description of how to add states to summary pages here: https://wiki-40m.ligo.caltech.edu/DailySummaryHelp#How_to_Define_and_Implement_States.

  11473   Fri Jul 31 10:36:22 2015 SteveUpdatePEMX seismo station short cable removed

 

Quote:

Atm1,  New short-50" long cable was installed at ETMY end ( Y-station ) between Guralp-B ( MIT ) and granite base.

Interface box input 2 was left connected to cable 1 and input 1 to cable 2. This plot shows no change.

 

Atm2, Than I swapped the two long cables at the interface box

                                                                                                   Now the signal seems to be ok <2 Hz,

                                                                                                                                                       >2 Hz some problem exist.

      Channel Name Location Seismometer 40m long cable

Interfacebox input

 

 50" short cable

C1:PEM-RMS_GUR2X_.... ETMX Guralp -A  2   2                             Jenne's friend                
C1:PEM-RMS_GUR1X_.... ETMY  Guralp-B  1   1  Koji

I will look for more bad soldering tomorrow. How many cables did she make?

 

 

We have to redo this cable also

Attachment 1: IMG_0009.JPG
IMG_0009.JPG
  11472   Thu Jul 30 19:12:52 2015 IgnacioUpdateIOOYAW and PIT WFS Wiener filtering

Rana pointed out that another way to mitigate seismic motion at in the mode cleaner would be to look at the YAW and PITCH output  channels of the WFS sensors that control the angular alignment of the mode cleaner. 

I downloaded 45 mins of data from the following two channels:

C1:IOO-WFS1_YAW_OUT_DQ

C1:IOO-WFS1_PIT_OUT_DQ

And did some quick offline Wiener filtering with no preweighting, the results are shown in the PSD's below,

and

I'm quite surprised at the Wiener subtraction obtained for the YAW signal, it required no preweighting and there is about an order of magnitude improvement in our region of interest, 1-3 Hz. The PIT channel didn't do so bad either.

 

Attachment 1: YAW.png
YAW.png
Attachment 2: PIT.png
PIT.png
  11471   Thu Jul 30 18:58:36 2015 JessicaUpdateGeneralALS Delay Line Box Front Panel Testing

I tested both of the front panels (conductive and isolated SMAs) with the ALS Delay Line Box by driving extremely close frequencies through the cables. By doing this, we would expect that a spike would show up in the PSD if there was crosstalk between the cables. 

In the plots below, for the conductive panel, the frequencies used were

               X Arm:  22.329 MHz                        Y Arm: 22.3291 MHz        

For the isolated panel, the frequencies were

              X Arm: 22.294 MHz                         Y Arm: 22.2943 MHz    

This gives a difference of 100 Hz for the conductive panel and 300 Hz for the isolated panel. Focusing on these areas of the PSD, it can be seen that in the Y Arm cable there is a very clear spike within 30 Hz of these differences when frequencies are being driven through both cables as opposed to the signal being in only the Y Arm. In the X Arms, the noise in general is higher when both cables are on, but there is no distinct spike at the expected frequencies. This indicates that some sort of crosstalk is probably happening due to the strong spikes in the Y Arm cables.          

 

Attachment 1: Xarm_diff.png
Xarm_diff.png
Attachment 2: Yarm_diff.png
Yarm_diff.png
Attachment 3: Xarm_isolated.png
Xarm_isolated.png
Attachment 4: Yarm_isolated.png
Yarm_isolated.png
  11470   Thu Jul 30 15:58:00 2015 ericqUpdateLSCBeat note Alignment fluctuation effects measured

However, I wonder how much of the low frequency noise can be explained by instability of the beat alignement on the PSL table, and how this might be quantified. 

I followed my hunch, and the truth comes out.

I recalled that the aLIGO demod board has a handy DB9 output on the back panel for the detected power at the RF and LO inputs. I hooked this up into the BEATY ADC channels while checking the ALSX spectrum in IR lock. 

This is assuredly the limiting factor in our ALS sensitivity.

Note: I'm calling the fluctuations of the beatnote amplitude "RF Amplitude RIN," to put things in reasonble units. I haven't looked up the board's conversion of dBm to V, but the LO should be around 0dBm in this measurement. 

The coherence between the phase tracker output and the LO amplitude is significant over a broad range, mostly dipping where real cavity motion peeks up into the spectrum. 

Also, the feature from 10-100Hz in the RIN spectrum is one I've often seen directly in ALS spectra when beatnote alignement is bad or the beatnote frequency is high, convincing me further that this is what's to blame. 

So: what do we do? Is there anything we can do to make the green alignment more stable?

Attachment 1: RF_RIN.png
RF_RIN.png
Attachment 2: RF_RINspec.png
RF_RINspec.png
Attachment 3: RFampCoh.xml.zip
  11469   Thu Jul 30 15:24:54 2015 SteveUpdatePEMY sesimostation is back on

Atm1,  New short-50" long cable was installed at ETMY end ( Y-station ) between Guralp-B ( MIT ) and granite base.

Interface box input 2 was left connected to cable 1 and input 1 to cable 2. This plot shows no change.

 

Atm2, Than I swapped the two long cables at the interface box

                                                                                                   Now the signal seems to be ok <2 Hz,

                                                                                                                                                       >2 Hz some problem exist.

      Channel Name Location Seismometer 40m long cable

Interfacebox input

 

 50" short cable

C1:PEM-RMS_GUR2X_.... ETMX Guralp -A  2   2                             Jenne's friend                
C1:PEM-RMS_GUR1X_.... ETMY  Guralp-B  1   1  Koji

I will look for more bad soldering tomorrow. How many cables did she make?

 

 

Attachment 1: NewShortCable-Y-B-Gur2.png
NewShortCable-Y-B-Gur2.png
Attachment 2: interfaceInputSwapped.png
interfaceInputSwapped.png
Attachment 3: sameasAtm2.png
sameasAtm2.png
  11468   Thu Jul 30 14:42:03 2015 ericqUpdateLSCaLIGO demod board lives!

ALS is not currently limited by the demod board or whitening electronics.

The noise budget in the green locking paper shows the main noise sources to be these two, plus the residual fluctuations of the green PDH loop. 

So, one next step is AUX PDH noise budget. 

However, I wonder how much of the low frequency noise can be explained by instability of the beat alignement on the PSL table, and how this might be quantified. 


Yesterday, I put together a few measurements to asses whether the new demod board has moved us in the right direction. Specifically I measured the output of the phase tracker in the following states, adjusting the phase tracker gain to maintain a ~2kHz UGH (but no boost on):

  • Whitening chassis inputs terminated. BEAT_I input channels were given a 3000 count offset to give the phase tracker something to work with. This is a typical beatnote amplitude with the new RF amplifiers. 
  • aLIGO LSC demod board driven with an SRS SD345 at 30MHz. (First with +3dBm into the splitter, which is about what it sees with the green beatnotes, then with +13dBm into the splitter, to give the board the +10dBm LO it expects)
  • Arms locked with POX, POY. AUX laser temperature servos on. Green beatnotes in the 20-40MHz range. 

Results: The beat frequency spectrum is above the measured demod board and whitening chassis/ADC noise at all frequencies. It's a little close at 10Hz. 

One nice feature is that the beat spectra are far more similar to each other than they used to be. RMS noise is in the 300-400Hz range, which isn't mindblowing, but not terrible. On the order of 50 pm for each arm. Most of this comes from below 10Hz. 

Another thing to note is that, when we switch in the 50m cables, we should win a fair bit of Hz/V gain and push down these noises futher. (We're currently using 30m cables.)


By looking at some coherences, we can attribute some of the noise when IR locked to both colors of PDH loops. 

Specifically, the coherence with the Green PDH error implicates the residual frequency noise of the AUX laser above a few hundred Hz, whereas the feature from 20-50Hz is probably real cavity motion, not ALS sensing noise. Some of the 1-3Hz noise is from real suspension/stack resonances too. 


If it turns out that we do want to push the demod board noise down further, we could think about increasing the RF amplification. Driving the board harder translates directly to better noise performance. The 60Hz harmonics aren't so exciting, but not the end of the world.


Data files are attached, if you're in to that sort of thing. 

Attachment 1: partialALSbudget.png
partialALSbudget.png
Attachment 2: demodDriveLevels.png
demodDriveLevels.png
Attachment 3: ALScoherences.png
ALScoherences.png
Attachment 4: partialALSbudget.zip
  11467   Thu Jul 30 14:27:18 2015 EveUpdateSummary PagesALS, ASC, LSC Summary Pages

I've switches the ALS, ASC, and LSC plots on the summary pages from plotting raw frames, to plotting minute trends, instead. Now, the plots contain information, instead of being completely blank, but data is not recorded on the plots after 12UTC.

Typically, I make changes to the summary pages on my own version of the pages, found at https://ldas-jobs.ligo.caltech.edu/~eve.chase/summary/day/, where I change the summary pages for June 30 and then import such changes into the main summary pages. 

 

  11466   Thu Jul 30 13:34:52 2015 KojiUpdatePEMY sesimostation is back on

Please check the spectra. If something is wrong, please swap the cables between X and Y in order to see if the cable is still the issue. I believe the cable was nicely made as I carefully checked the connection twice or more during and after the soldering work.

  11465   Thu Jul 30 11:47:54 2015 KojiSummaryCDSStatus of the frame data syncing

Today it was synced at 5AM but that was all.

40m:

controls@nodus|minute > pwd
/frames/trend/minute
controls@nodus|minute > ls -l 11222|tail
-rw-r--r-- 1 controls controls 35521183 Jul 29 21:59 C-M-1122264000-3600.gwf
-rw-r--r-- 1 controls controls 35509281 Jul 29 22:59 C-M-1122267600-3600.gwf
-rw-r--r-- 1 controls controls 35511705 Jul 29 23:59 C-M-1122271200-3600.gwf
-rw-r--r-- 1 controls controls 35809690 Jul 30 00:59 C-M-1122274800-3600.gwf
-rw-r--r-- 1 controls controls 35752082 Jul 30 01:59 C-M-1122278400-3600.gwf
-rw-r--r-- 1 controls controls 35927246 Jul 30 02:59 C-M-1122282000-3600.gwf
-rw-r--r-- 1 controls controls 35775843 Jul 30 03:59 C-M-1122285600-3600.gwf
-rw-r--r-- 1 controls controls 35648583 Jul 30 04:59 C-M-1122289200-3600.gwf
-rw-r--r-- 1 controls controls 35643898 Jul 30 05:59 C-M-1122292800-3600.gwf
-rw-r--r-- 1 controls controls 35704049 Jul 30 06:59 C-M-1122296400-3600.gwf
controls@nodus|minute > ls -l 11223|tail
total 139616
-rw-r--r-- 1 controls controls 35696854 Jul 30 08:02 C-M-1122300000-3600.gwf
-rw-r--r-- 1 controls controls 35675136 Jul 30 08:59 C-M-1122303600-3600.gwf
-rw-r--r-- 1 controls controls 35701754 Jul 30 09:59 C-M-1122307200-3600.gwf
-rw-r--r-- 1 controls controls 35718038 Jul 30 10:59 C-M-1122310800-3600.gwf

LDAS Minute trend:

[koji.arai@ldas-pcdev3 C-M-11]$ pwd
/archive/frames/trend/minute-trend/40m/C-M-11
[koji.arai@ldas-pcdev3 C-M-11]$ ls -l |tail
-rw-r--r-- 1 1001 1001 35518238 Jul 29 19:59 C-M-1122256800-3600.gwf
-rw-r--r-- 1 1001 1001 35514930 Jul 29 20:59 C-M-1122260400-3600.gwf
-rw-r--r-- 1 1001 1001 35521183 Jul 29 21:59 C-M-1122264000-3600.gwf
-rw-r--r-- 1 1001 1001 35509281 Jul 29 22:59 C-M-1122267600-3600.gwf
-rw-r--r-- 1 1001 1001 35511705 Jul 29 23:59 C-M-1122271200-3600.gwf
-rw-r--r-- 1 1001 1001 35809690 Jul 30 00:59 C-M-1122274800-3600.gwf
-rw-r--r-- 1 1001 1001 35752082 Jul 30 01:59 C-M-1122278400-3600.gwf
-rw-r--r-- 1 1001 1001 35927246 Jul 30 02:59 C-M-1122282000-3600.gwf
-rw-r--r-- 1 1001 1001 35775843 Jul 30 03:59 C-M-1122285600-3600.gwf
-rw-r--r-- 1 1001 1001 35648583 Jul 30 04:59 C-M-1122289200-3600.gwf

  11464   Thu Jul 30 10:38:18 2015 SteveUpdatePEMY sesimostation is back on

Koji soldered new 50" long cable for the Y station.

 

Attachment 1: Guralps_are_back_on.png
Guralps_are_back_on.png
Attachment 2: Ystation.jpg
Ystation.jpg
  11463   Thu Jul 30 03:19:24 2015 ericqUpdateLSCBack towards PRFPMI

The refreshed ALS didn't look so bad today (elog forthcoming), so I decided to give PRFPMI locking a shot tonight. I was able to hold the PRMI while swinging through resonsance, but transitions to RF signals failed. Demod angles / whitening gains/ etc. etc. all need to be rechecked

Some little things here and there that got cleaned up...

  • The PRM oplev beam was being blocked. Why? I removed the block. Should recheck OLTF/spot size on QPD. 
  • ALS -> CARM, DARM signs changed, maybe because I've used the delayed beat as the RF input on the demod board, whereas I imagine it may have been the LO in the beatbox. No big deal.
  • REFL165 whitening gain and input matrix updated. Should recheck demod angles.
  • PRMI triggering settings weren't being set in the script. It's important to include arm transmission signals, since POP2F signals can momentarily dive when swinging through resonance. 
  • I should revisit phase tracker UGF normalization. I/Q amplitudes are varying quite a bit from lock to lock. 
  • PRC angular feedforward disabled for now; need to remeasure the witness/target data with DC coupled ITM oplevs
  • I think there has been a little bit of MC servo tweaking since our last locks, may need to recheck AO TF / gains. 
  11462   Thu Jul 30 02:06:20 2015 IgnacioUpdateIOOMC2 <-> MCL Actuator TF fitted

Eric downloaded MC2 to MCL transfer function data (H) as well as its inverse, MCL to MC2 (Hinv). He also downloaded new MCL and MC2 data.

I used vectfit to fit the MC2 to MCL transfer function, 

The ZPK parameters for this fit were,

Zeros              1278.36719876674 + 0.00000000000000i
                   -100.753249679343 + 0.00000000000000i
                   -18.6014192997845 + 13.0294910760217i
                   -18.6014192997845 - 13.0294910760217i

Poles              -1.11035771175328 + 7.03549674098987i
                   -1.11035771175328 - 7.03549674098987i
                   -18.8655320274072 + 0.00000000000000i
                   -690.294337433234 + 0.00000000000000i

Gain               0.00207206036014220

Using the above vectfit model, I filtered the raw MC2 signal to get 'MCL'. The PSD's of the raw MCL data and the filtered MC2 result is shown below,

The lack of accuracy of the transfer function at replicating MCL at frequencies lower than 0.7Hz is expected, the vectfit model I generated fails to follow accurately the raw transfer function data. My question: Does it matter? My guess: Probably not. In order to mitigate seismic noise from the mode cleaner we are mainly concerened with the 1-3 Hz region.

I also used vectfit to fit the transfer function for MCL to MC2,

This one was harder to fit accurately for some reason, I could do it with four pairs of zeros and poles but it took some preweighting.

The ZPK parameters for the above fit were, 

Zeros              0.173068278283995 + 0.00000000000000i
                   0.995140531040529 + 0.0268079821980457i
                   0.995140531040529 - 0.0268079821980457i
                   0.894476816129099 + 0.00000000000000i

Poles              -19.9566906920707 + 18.0649464375308i
                   -19.9566906920707 - 18.0649464375308i
                   -109.275971483008 + 0.00000000000000i
                   -1791.88947801703 + 0.00000000000000i

Gain               1237.46417532120

Similarly, using this ZPK model, I filtered the MCL signal to get 'MC2'. I plotted the PSD for the MC2 signal and the filtered MCL to get,

Again, the lack of accuracy of the filtered MC2 at replicating MCL below 0.7 Hz and above 12 Hz is due to the inverse transfer function failing to converge in these ranges.

Attachment 1: TF_BODE.png
TF_BODE.png
Attachment 2: MC2_2_MCL.png
MC2_2_MCL.png
Attachment 3: TF_INV_BODE.png
TF_INV_BODE.png
Attachment 4: MCL_2_MC2.png
MCL_2_MC2.png
  11461   Wed Jul 29 21:40:39 2015 KojiSummaryCDSStatus of the frame data syncing

The trend data hasn't been synced with LDAS since Jul 27 5AM local.

40m:

controls@nodus|minute > pwd
/frames/trend/minute
controls@nodus|minute > ls -l 11222 | tail
total 590432
-rw-r--r-- 1 controls controls 35758781 Jul 29 11:59 C-M-1122228000-3600.gwf
-rw-r--r-- 1 controls controls 35501472 Jul 29 12:59 C-M-1122231600-3600.gwf
-rw-r--r-- 1 controls controls 35296271 Jul 29 13:59 C-M-1122235200-3600.gwf
-rw-r--r-- 1 controls controls 35459901 Jul 29 14:59 C-M-1122238800-3600.gwf
-rw-r--r-- 1 controls controls 35550346 Jul 29 15:59 C-M-1122242400-3600.gwf
-rw-r--r-- 1 controls controls 35699944 Jul 29 16:59 C-M-1122246000-3600.gwf
-rw-r--r-- 1 controls controls 35549480 Jul 29 17:59 C-M-1122249600-3600.gwf
-rw-r--r-- 1 controls controls 35481070 Jul 29 18:59 C-M-1122253200-3600.gwf
-rw-r--r-- 1 controls controls 35518238 Jul 29 19:59 C-M-1122256800-3600.gwf
-rw-r--r-- 1 controls controls 35514930 Jul 29 20:59 C-M-1122260400-3600.gwf

 

LDAS Minute trend:

[koji.arai@ldas-pcdev3 C-M-11]$ pwd
/archive/frames/trend/minute-trend/40m/C-M-11
[koji.arai@ldas-pcdev3 C-M-11]$ ls -l | tail
-rw-r--r-- 1 1001 1001 35488497 Jul 26 19:59 C-M-1121997600-3600.gwf
-rw-r--r-- 1 1001 1001 35477333 Jul 26 21:00 C-M-1122001200-3600.gwf
-rw-r--r-- 1 1001 1001 35498259 Jul 26 21:59 C-M-1122004800-3600.gwf
-rw-r--r-- 1 1001 1001 35509729 Jul 26 22:59 C-M-1122008400-3600.gwf
-rw-r--r-- 1 1001 1001 35472432 Jul 26 23:59 C-M-1122012000-3600.gwf
-rw-r--r-- 1 1001 1001 35472230 Jul 27 00:59 C-M-1122015600-3600.gwf
-rw-r--r-- 1 1001 1001 35468199 Jul 27 01:59 C-M-1122019200-3600.gwf
-rw-r--r-- 1 1001 1001 35461729 Jul 27 02:59 C-M-1122022800-3600.gwf
-rw-r--r-- 1 1001 1001 35486755 Jul 27 03:59 C-M-1122026400-3600.gwf
-rw-r--r-- 1 1001 1001 35467084 Jul 27 04:59 C-M-1122030000-3600.gwf

 

  11460   Wed Jul 29 17:51:56 2015 IgnacioUpdatePEMAccelerators moved back to MC1 and MC2

We are done taking accelerator huddle test data. So I moved back all six accelerometers and cables to MC1 and MC2. I also relabel each of the accelerometers properly since the labels on them were confusing.

QED

 

Attachment 1: FullSizeRender.jpg
FullSizeRender.jpg
Attachment 2: FullSizeRender_2.jpg
FullSizeRender_2.jpg
  11459   Wed Jul 29 14:32:01 2015 SteveUpdateGeneralHow not to solder

 

Quote:

 

Quote:

Koji and Steve,

The result: bad Guralp x-arm cable.

I will swap the short cables tomorrow at the base.

 

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

This cable actually worked at 5-5-2015

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

Koji could pull out easily 11 of the wires  from their socket.

Attachment 1: coldSoldering.jpg
coldSoldering.jpg
  11458   Wed Jul 29 11:15:21 2015 JessicaSummaryLSCPSDs of Arms with seismometer subtraction

Ignacio and I downloaded data from the STS, GUR1, and GUR2 seismometers and from the mode cleaner and the x and y arms. The PSDs along the arms have the most noise at frequencies greater than 1 Hz, so we should focus on filtering in that area. The noise levels start dropping at around 30 Hz, but are still much higher than is seen at frequencies below 1 Hz. However, because the spectra is so low at frequencies below that, Wiener filtering alone injected a significant amount of noise into those frequencies and did not do much to reduce the noise at higher frequencies. Pre-filtering will be required, and I have started implementing a pre-filter, but with no improvements yet. So far, I have tried making a bandpass filter, but a highpass filter may be ideal in this case because so much of the noise is above 1 Hz. 

Attachment 1: Arms_PSD.png
Arms_PSD.png
Attachment 2: XArm_PSD.png
XArm_PSD.png
Attachment 3: YArm_PSD.png
YArm_PSD.png
  11457   Wed Jul 29 10:34:42 2015 IgnacioSummaryLSCCoherence of arms and seismometers

Jessica and I took 45 mins  (GPS times from 1122099200 to 1122101950) worth of data from the following channels:

C1:IOO-MC_L_DQ (mode cleaner)
C1:LSC-XARM_IN1_DQ (X arm length)
C1:LSC-YARM_IN1_DQ (Y arm length)

and for the STS, GUR1, and GUR2 seismometer signals.

The PSD for MCL and the arm length signals is shown below,

I looked at the coherence between the arm length and each of the three seismometers, plot overload incoming below,

For the coherence between STS and XARM and YARM,

  

For GUR1,

  

Finally for GUR2,

 

A few remarks:

1) From the coherence plots, we can see that the arm length signals are coherent with the seismometer signals the most from 0.5 - 50 Hz. This is most evident in the coherence with STS. I think subtraction will be most useful in this range. This agrees with what we see in the PSD of the arm length signals, the magnitude of the PSD starts increasing from 1 Hz and reaches a maximum at about 30 Hz. This is indicative of which frequencies most of the noise is present.

2) Eric did not remember which of  GUR1 and GUR2 corresponded to the ends of XARM and YARM. So, I went to the end of XARM, and jumped for a couple seconds to disturb whatever Gurald was in there. Using dataviewer I determined it was GUR1. Anyways, my point is, why is GUR1 less coherent with both arms and not just XARM?  Since it is at the end of XARM, I was expecting GUR1 to be more coherent with XARM. Is it because, though different arms, the PSD's of both arms are roughly the same? 

3) Similarly, GUR2 shows about the same levels of coherence for both arms, but it is more coherent. Is GUR2 noisier because of its location?

Code: ARMS_COH.m.zip

Attachment 1: PSD_ARMS_MCL.png
PSD_ARMS_MCL.png
Attachment 2: XARM_STS_COH.png
XARM_STS_COH.png
Attachment 3: YARM_STS_COH.png
YARM_STS_COH.png
Attachment 4: XARM_GUR1_COH.png
XARM_GUR1_COH.png
Attachment 5: YARM_GUR1_COH.png
YARM_GUR1_COH.png
Attachment 6: XARM_GUR2_COH.png
XARM_GUR2_COH.png
Attachment 7: YARM_GUR2_COH.png
YARM_GUR2_COH.png
Attachment 8: ARMS_COH.m.zip
  11456   Tue Jul 28 20:42:50 2015 JessicaSummaryGeneralNew Seismometer Data Coherence

I was looking at the new seismometer data and plotted the coherence between the different arms of C1:PEM_GUR1 and C1:PEM_GUR2. There was not much coherence in the X arms, Y arms, or Z arms of each seismometer, but there were within the x and y arms of the seismometer.

I think the area we should focus on with filtering is lower ranges, between 0.01 and 0.1, because that it where coherence is most clearly high. It is higher in high frequencies but also incredibly noisy, meaning it probably wouldn't be good to try to filter there. 

Attachment 1: Coherence1.png
Coherence1.png
Attachment 2: Coherence2.png
Coherence2.png
  11455   Tue Jul 28 17:07:45 2015 JamieUpdateGeneralData missing
Quote:

For the past couple of days, the summary pages have shown minute trend data disappear at 12:00 UTC (05:00 AM local time). This seems to be the case for all channels that we plot, see e.g. https://nodus.ligo.caltech.edu:30889/detcharsummary/day/20150724/ioo/. Using Dataviewer, Koji has checked that indeed the frames seem to have disappeared from disk. The data come back at 24 UTC (5pm local). Any ideas why this might be?

Possible explanations:

  • The data transfers to LDAS had been shut off while we were doing the DAQ debugging. I don't know if they have been turned back on.  Unlikely this is the problem since you would probably see no data at all if this were the case.
  • wiper script parameters might have been changed to store less of the trend data for some reason.
  • Frame size is different and therefore wiper script parameters need to be adjusted.
  • Steve deleted it all.
  • ...
  11454   Tue Jul 28 16:42:25 2015 SteveUpdateGeneralJamies entry was deleted

Sorry Jamie, I accidentally deleted your elog entry #11453

  11453   Tue Jul 28 15:06:27 2015 SteveUpdateIOOPSL HEPA turned on

crying

Attachment 1: noHepa.jpg
noHepa.jpg
  11452   Tue Jul 28 15:05:09 2015 SteveUpdatesafetyfire alarm test ? no

We just had fire alarm trigged avacuation of the 40m lab.

It turned out that the CES building second floor sensor caused this action.

Attachment 1: 6minGaps.png
6minGaps.png
  11451   Tue Jul 28 14:58:59 2015 SteveUpdateGeneraldo not place anything on optical table tops

angrySpecially heavy items: old analoge scope or hardware loaded boxes......etc

 The table cover section holding crossbars are not evenly spaced.no

You have to center each cover section on the cross bar so it is supported on both sides !

 

I will clean up on this table tomorrow

 

 

Attachment 1: tabletops!.jpg
tabletops!.jpg
Attachment 2: tabletops!!.jpg
tabletops!!.jpg
  11450   Tue Jul 28 09:31:35 2015 IgnacioUpdateGeneralNewest accelerometer huddle test

I downloaded new accelerometer huddle test data from last night and analyzed it. This new data set is ~55 mins and uses the same Wiener filter parameters as previous huddle test analysis, the main difference being six accelerometers used in the Wiener filter and the improved experimental set up.

After computing the ASD for the self noise for each of the six accelerometers, (being witnessed by the remaining five), we get,

Now computing the mean of the above signals and the corresponding error bars gives the following result,

Comparing to prevoius huddle tests, I can note two trends on the Wiener subtraction:

1) When using six accelerometers, the subtraction above ~8 Hz drastically improves.

2) When using three accelerometers, there is better cancellation in the 1-5 Hz region, see http://nodus.ligo.caltech.edu:8080/40m/11442. This might have to do with how much more closer the accelerometers are to each other? 

Attachment 1: selfnoise_allsix_miso_newest.png
selfnoise_allsix_miso_newest.png
  11449   Tue Jul 28 05:00:03 2015 IgnacioUpdateGeneralSeismometer cans

I've have been talking a little bit with Steve about the seismometer enclosures.

We want to improve on the current stainless steel cans that cover the two Guralps at the end of the arms. In order to do this, we want to cover the interior of the cans with copper foil to improve the thermal conductivity of the enclosure to better control the temperature inside it. Ideally, we would want to copper plate the cans, but cost and difficulty has been an issue.

I have done some rough calculations and it seems that we need a copper layer of thickness being about a third that of the stainless steel can. This happens to be around 0.5-0.6 mm since we have 16 gauge (~1.6 mm) stainless steel cans. 

After wrapping the cans interior with copper, we will insulate them with foam in order to improve its thermal inertia. We want to probably use the same foam that Megan has been using for her seismometer enclosure. I have yet to think about a heater, but something similar to Megans resistor thing would work only smaller. I would be placed inside the can, right on the center of its bottom in order to ditribute heat evenly.

 

  11448   Mon Jul 27 17:51:06 2015 EveUpdateSummary PagesNew summary page tabs and other improvements

The summary pages can still be found at https://nodus.ligo.caltech.edu:30889/detcharsummary/ (EDIT: in an older version of this post I listed an incorrect url). They are operational and include data from some channels for intermittent periods of time.

 

Motivation: to make the summary pages more informative and useful for all

 

What I did:

I have added tabs for ALS, ASC, and LSC subsystems. While there is currently no data on the plots, I plan on checking all channels with DataViewer to set appropriate axis ranges so that we can actually see the data.

I altered which channels are used to represent spectra for OpLev systems to more appropriately provide PSDs.

I've changed the check code status page to include "warning" labels. Previously, when the summary pages ran, resulting in a warning message, the check code status page would list this as an "error", implying that the summary pages were not properly produced.

 

Results:

All features were implemented, but I need to investigate some of these channels to understand why we aren't seeing many channels in the plots. I am working on some other changes to the summary pages, including providing a Locked status which will only show data in a timeseries for a selected period of time.

  11447   Mon Jul 27 16:47:53 2015 ericqUpdateIOOMC2 -> MCL Actuator TF

Our noise cancellation SURFS will be doing online subtraction on the mode cleaner length, among other things. 

I made a measurement of the MC2 actuator transfer function by injecting noise from 1-100Hz into LSC_MC2_EXC for about 15 minutes, then estimating the TF from MC2_OUT to IOO_MC_L with CSD/PSD. The inverse of this TF will be applied to their Wiener target data to give us the direct subtration filter we want. 

I figured I would post the results here for posterity. The last time this seems to have been done is in ELOG 5900. There are some differences found here, the effective Q of the 1Hz pendulum resonance seems lower, and the behavior above 20Hz has definitely changed. 

IIR fits will be done by one of the SURFs to be used in their Wiener filter calculations. 

Data attached!

Attachment 1: mc2_2_mcl.png
mc2_2_mcl.png
Attachment 2: MC2_2_MCL_TF.txt.zip
  11446   Fri Jul 24 23:08:53 2015 IgnacioUpdatePEMMC1 accelerators moved for future huddle test

I have moved the MC1 accelerators and cable to the huddle test set up, in order to see how a six witness huddle test with the improved set up will do. 

Here is a picture of the accelerometer set up,

Our motivation for doing this is to see if more witness signals used in the Wiener filter really does indeed improve subtraction, as it was seen from previous huddle results, specially in the region above 10 Hz.

  11445   Fri Jul 24 20:32:15 2015 ericqUpdateElectronicsLSC LO distribution box power button replaced

As happened with the RF distribution box in the IOO rack a while back, the shiny blue power button in the LSC LO distribution box failed today. I replaced it with a simple switch, but since the original was a double throw, the replacement was way too big to fit without major panel surgery. So, instead, I installed it in the grille on the roof of the chassis. It a tight press/snap fit, though; I don't think it is at risk of easily coming loose. 

After reinstalling the box, I confirmed that POX POY and AS55 could all lock arms, so I deem the operation a success.

Before:

After:

Attachment 1: 2015-07-24_15.43.56.jpg
2015-07-24_15.43.56.jpg
Attachment 2: 2015-07-24_16.57.19.jpg
2015-07-24_16.57.19.jpg
  11444   Fri Jul 24 18:12:52 2015 Max IsiUpdateGeneralData missing

For the past couple of days, the summary pages have shown minute trend data disappear at 12:00 UTC (05:00 AM local time). This seems to be the case for all channels that we plot, see e.g. https://nodus.ligo.caltech.edu:30889/detcharsummary/day/20150724/ioo/. Using Dataviewer, Koji has checked that indeed the frames seem to have disappeared from disk. The data come back at 24 UTC (5pm local). Any ideas why this might be?

  11443   Fri Jul 24 13:49:09 2015 SteveUpdatesafetyLock doors please !

Thursday morning I found the control room emergency exit not locked.

Please check the doors when leaving the lab , specially when you are the last one out.

  11442   Thu Jul 23 21:12:14 2015 IgnacioUpdateGeneralNewer accelerometer huddle test data + detrending

In the last post concerning the self noise of the accelerometers, I mentioned the differences between the two data sets I was playing with. In order to give a more concrete analysis of the accelerometers self noise, we came to the conclusion that data taking time should be the same.

The plots below show the analysis for the following two datasets:

Old Data:  6 accelerometers, no cables clamped, no box, 55 mins worth of data.

Newer data: 3 accelerometers, cables clamped, foam box put on placed and completely sealed, 57.66 mins worth of data, (we had 20 mins of data in the previous data set).

Filter parameters were kept the same in all calculations, the only change that was added to the analysis was the detrending of the signals using the detrend function on Matlab, this improved the results as the plots show. I also plotted the error bars for the Wiener filtered result for reference as well as the manufactures claimed self noise.

   

After detrending the data and taking a longer dataset we can see the improvement brought upon by the foam box in the low frequency band of 0.5 - 10 Hz, as shown in the bottom left plot. There is a lot of noise that needs to be cancelled out from 10 Hz and on, which brings to our attention the plot on the bottom right corner. This plot uses the old data but uses all six accelerometers as witnesses, it also improved overall after having detrended the data, but what is peculiar about this plot is the fact that it manages to mitigate the higher frequency 10 - ~100 Hz band noise. 

 

Attachment 1: old_data_1.png
old_data_1.png
Attachment 2: old_data_2.png
old_data_2.png
Attachment 3: new_data.png
new_data.png
Attachment 4: six_old_data.png
six_old_data.png
  11441   Thu Jul 23 20:57:15 2015 JessicaSummaryGeneralApplying Pre-filter to data before IIR Wiener Filtering

I updated my bandpass filter and have included the bode plot below in Figure 1. It is a fourth order elliptic bandpass filter with a passband ripple of 1dB and a stopband attenuation of 30 dB. It emphasizes the area between 3 and 40 Hz.

Below, I applied this filter to the huddle test data. The results from this were only slightly better in the targeted region than when no pre-filter was applied. 

When I pre-filtered the mode cleaner data and then used an IIR wiener filter, I found that the results did not differ much from the data that was not pre-filtered. I'm not sure yet if I'm targeting the right region of this data with my bandpass filter, and will be looking more into choosing a better region. Also, I am only using certain regions of ff when calculating the transfer function, and need to optimize that region also. I uploaded the code I used to make these plots to github.

Attachment 1: BodePlot.png
BodePlot.png
Attachment 2: acc_bandpass.png
acc_bandpass.png
Attachment 3: mcl_seis.png
mcl_seis.png
  11440   Thu Jul 23 20:54:42 2015 JessicaUpdateGeneralALS Delay Line Box

The front panels for the ALS delay line box came in last week. Some of the holes for the screws were slightly misaligned, so I filed those and everything is now put together. I just need to test both front panels to determine if the SMAs should be isolated or not.

 

Koji had also suggested making the holes in the front and back panel conical recesses so that flat head screws could be used and would counteract the anodization of the panel and avoid the SMAs being isolated. I think if we did that then conductivity would be ensured throughout the panel and also through the rest of the box. I also think one way we could test this before drilling conical recesses would be to test both front panels now, as one has isolated SMAs and one has conductive SMAs. If the anodization of the panel isolated the SMA regardless, we could potentially figure this out by testing both panels. But, would it also be that it is possible that the isolation of the SMA itself does not matter and so this test would tell us nothing? Is there a better way to test if the SMAs are being isolated or not? Or would this be more time consuming than just drilling conical recesses as a preventative measure?

  11439   Thu Jul 23 15:41:41 2015 SteveUpdatePEMfitting ants with TERRO

Pasadena got 0.2" of  rain on Saturday. Temperatures were high with high humidity since than.The ants were back in the Control room east side benches.

We have started using TERRO Liquid Ant Baits in January 2015   This worked very well to this point.

Tree new packages were opened  yesterday and the ants are gone.

We can conclude that these baits must be replaced after 6 mounts.

The liquid baits contains BORAX  and it is safe.

 

  11438   Thu Jul 23 03:09:05 2015 ericqUpdateLSCaLIGO demod board lives!

I'm a little mystified. Peeking inside the aLIGO demod board, I saw that the reason that two of the channels weren't working was that their power connectors weren't plugged in, so no real mystery there. 

I hooked up the board at the electronics bench, and found the noise to be completely well behaved, in contrast to the measurements I made when it was in the LSC rack. I've taken it back out to the LSC rack, and given it the X beatnote, and it seems to be performing pretty well. 


I switched between the aLIGO demod board and beatbox during the same lock / beat. The LSC board performs margnially better from 3-100 Hz. The high frequency noise comes from the green PDH loop (coherence is near one above a few hundred Hz), so we don't expect any difference there. 

To me, the beatbox noise looks like there is a broad feature that is roughly the same level as the real cavity motion in the 10-100 Hz range. So, I think we should use the aLIGO board afterall, presuming the noise doesn't shoot back up when I remount it in the rack...


The ALS noise is getting low enough where our normal approach of measuring ALS sensing noise by simply taking the PSD of the signal when the arm is PDH locked is not quite valid anymore, as it is sensing the real cavity fluctuations. Doing a frequency domain coherent subtration of the PSDs suggests a sensing noise RMS of ~150Hz for ALSX. 

When the X arm is locked on ALS, POX sees about 250Hz RMS out of loop noise, which isn't the greatest; however, I used to be happy with 500Hz. By eye, sweeping through IR resonance is smoother. The real test is to get the Y arm ALS running, and swing it through PRFPMI resonance...


Fair warning, the LSC rack area is not so tidy right now, the demod board is resting on a stool (but not in the way of walking down the arm). I'll clean this up tomorrow. 

Attachment 1: beatbox_vs_aLIGO.png
beatbox_vs_aLIGO.png
ELOG V3.1.3-