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ID Date Author Type Category Subject
17406   Thu Jan 19 20:35:54 2023 AnchalUpdateASCInstalled 2 flipper mirrors for handingl MC reflection beam to camera

Today I installed two flipper mirrors M3 and M4 (see attached photo) to create alternate route for MC reflection camera beam. Both these mirrors are Y1-1037-45S. In nominal operation where IMC is using the WFS, we will keep M3 upright and M4 flipped down. When using WFS for AS, M3 will be flipper down and M4 will be upright to save the camera from the high intensity MC reflection beam.

Note that everytime M3 is flipper and put back upright, the alignment into WFS would need to be tuned as the flipper apparatus does not come back to same alignment everytime. I centered the beams on the WFS heads today and zeroed RF offsets usingC1IOO_WFS_MASTER>!Actions>Correct WFS RF Offsets script. After this, the IMC WFS loops are working as expected atleast for last 15 minutes that I have monitored them. Hopefully, this will remain consistent.

### Upcoming work:

• Change the steering mirror that steers the beam to black hole to be a flipper mirror too as AS beam strength (measured when MICH was locked to bright port) is 0.3 mW and IMC WFS heads combined power is 0.5 mW in nominal operation, so we can not afford to dump any AS beam light.
• Put flipper mirror M1 and fixed mirror M2 mentioned in 40m/17320 for steering AS beam to IMC WFS heads.
Attachment 1: PXL_20230120_041313615.jpg
17407   Fri Jan 20 20:13:20 2023 AnchalUpdateASCInstalled 2 flipper mirrors for handingl MC reflection beam to camera

After discussions with Yuta, I figured that a better optical layout is possible which does not interfere with the existing IMC WFS path at all. So I reset the IMC WFS path today (and zeroed RF offsets again) and changed the MC reflection camera and MC reflection beam dump (black hole) position to create space for a flipper mirror that will pop up in the IMC WFS path and steer in the AS beam. New proposed path is shown in the photo in cyan. Red is MC reflection beam, yellow is IFO reflection beam and orange is teh AS beam that we will pick up using flipper mirror M1. Note that I found an intense 6.4 mW ghost beam coming out of the interferometer in between IFO refl and MC refl beams. This beam is shown in pink which I have dumped now. This beam was earlier not dumped. We will need to investigate more on the source of this beam and correct it in the next vent.

Attachment 1: PXL_20230121_035908170.NIGHT.jpg
17408   Sat Jan 21 15:32:40 2023 AnchalUpdateASCAS WFS path nominally set

I've completed the beam redirection path for AS beam to WFS heads in a nominal way. By that I mean that all mirrors (M1, M2, M3, and M4) are now in their final positions and we will need to install one or two lenses to collimate the beam to match the mode that the WFS path is expecting as it has it's on the focusing lens before the photodiodes. For this last part, I think the fasted way would be to profile the beam and calculate the correct lens and position rather than trial and error as the beam intensity is very low for estimating the beam size by eye.

IMC WFS state: Flip M1 and M2 down.

AS WFS state: Flip M1 and M2 up.

Attachment 1: PXL_20230121_231740878.NIGHT.jpg
17412   Mon Jan 23 20:50:58 2023 AnchalUpdateASCAS WFS path beam profiled

I measured the expected beam profile by WFS photodiodes by measuring the beam when mode cleaner was unlocked from the point where beam is picked for WFS. See attachment 1 for beam details. z=0 is the point in the path where AS beam will merge.

For measuring the beam profile of AS beam, I had to focus it using a lens. I picked up a 360.6 mm ROC lens and placed it at z=-67 inch point. Then I profiled the beam at some comfortable section of the path and fitted it. with reverse z-axis. Using this method, I can place the lens back and obtain the original beam back. Attachment 2 shows this fitting process and identification of the original beam profiles. I plotted the AS beam profiles again in attachment 3 and saved them for seeding mode matching effort later. Note that we don't want to be super accurate here, so I did not do any error analysis, just wanted to finish this fast. Also pardon me for the bad quality plots, I did not want to learn Matlab plotting to make it beautiful.

Note: There is significant astigmatism in both IMC reflection beam and AS beam. This could be due to beam going through far off-center on lens. Something to keep in mind, again this measurement is not ideal in terms of precision but this large an astigmatism could not be due to measurement error.

Next:

• Identify correct len(s) and their positions
• Align the AS beam to WFS heads
• Test the full signal chain.
Attachment 1: WFSPathBeamProfile.pdf
Attachment 2: ASFocPathBeamProfile.pdf
Attachment 3: ASPathBeamProfile.pdf
17416   Tue Jan 24 21:04:59 2023 AnchalUpdateASCAS WFS path beam profiled

I completed the mode matching calculation today and found good solution with 360.6 mm ROC PLCX lens at -1.2 m from z=0 point. I placed the lens there today and aligned all mirrors to get centered beam on both WFS PDs when the flipper mirrors are flipper up. This alignment would probably require tweaking everying we flip the mirrors as the flipper mirrors do not come back to same position usually.

I mounted the modified WFS boards 111B and 112B next to the whitening filter boards of existing WFS. Now to switch over, onewould need to transfer the 8 RF lemo cables and the 2 IDE ribbon cables.

I'm working on rtcds model to read AS WFS data and handle it separately. I'll keep a WPICS binaruy switch to switch between IMC WFS or AS WFS. I need to figure out some build issues on this work still.

Attachment 1: ASBeamFocusingLens.png
17425   Thu Jan 26 15:56:30 2023 AnchalUpdateASC1X1 -5V sorenson tripped

[Yuta, Anchal]

 Quote: I mounted the modified WFS boards 111B and 112B next to the whitening filter boards of existing WFS.

The mounting of two additional WFS demodulation boards drew too much current on -5V rail which tripped the sorenson on 1X1. This was undetected until today. Because of this, the existing WFS boards were not working either. After investicgation to beam paths and PD to board signal chain, we found out this issue. We raised the current limit on -5V supply and it came back to 5V. This brought back functioning of the exisitng WFS boards as well. We increased the current limit slightly on +5V supply too as these boards take a lot of current on +/5 V rails. But we should do this more properly by knowing what current limit the supply is set to. We'll do this part in near future after reading the manuals/wiki.
IMC WFS loops are now working.

17444   Fri Feb 3 12:50:47 2023 AnchalUpdateASCAS WFS model changes and phase calibration

### Model and medm changes

After incrementally doing the model changes, I found out that the model was failing to build because of creation of a subsystem. If I just kept all divertor blocks out in the main model instead of in a single subsystem, the compilation works. Maybe the reason is because RCG can only take subsystems at base level which have top_names attribute. But I did nto test this, I just went with what works.

In summary, I added a new subsystem in c1ioo model called AWS (stands for Antisymmetric Wavefront Sensors). This subsystem and IOO subsystem receive teh WFS RF demodulated signals based on a single binary switch named C1:IOO-SEL_WFS_IMC_OR_AS. Value 0 connects the subsystem IOO to the inputs and value 1 connects AWS to the inputs. There is a switch on the left edge in the WFS screens now to select between the two.

Inside the AWS, the WFS I/Q phase rotation is done and then it goes into one of the two subsystems called AWS-XARM or AWS-YARM for using the AS for either XARM or YARM. THis is based on a single binary switch called C1:AWS-SEL_ARM_X_OR_Y. Value 0 selects output to XARM and value 1 selects output to YARM. There is a switch near top left of  C1AWS_XARM_WFS_MASTER.adl and C1AWS_YARM_WFS_MASTER.adl screens. I copied these screens from C1IOO_WFS_MASTER.adl, so they have same structure. See attachment 1. Any edits should be made to /opt/rtcds/caltech/c1/medm/c1ioo/master/C1AWS_XARM_WFS_MASTER.adl and simply run python opt/rtcds/caltech/c1/medm/c1ioo/master/createYARMWFSscreensFromX.py to create teh YARM screen from it.

Along with this, models c1scy and c1scx were edited also to take in IPC directly from c1ioo instead of going through RFM. We should phase out use of RFM eventually and directly connect all IPC connections with the ends.

### First tests

[Anchal, Yuta]

After the model is up and running, we flipped the WFS path to use AS beam. I switched the 8 RF outputs of the WFS from IMC WFS boads to AS WFS boards and switched the IDC connectors to WFS. Attachment 2 shows teh photo in this flipped state. Then we misaligned both ITMX and ETMX. First simple test was to check if we see the YARM PDH error signal when YARM was flashing. And indeed we saw that on all 16 channels. So next we locked YARM and injected 311 Hz line with 300 counts amplitude at ETMY. We looked for this peak in the Q channels of WFS outputs and adjusted all phases to 0.1 degrees to minimize Q signal to the noise floor. For WFS2 case, teh SNR is bit higher due to more power than WFS1 and their phase angle might be adjusted to even better degree but we did not got for it.

Then I used C1AWS_XARM_WFS_MASTER.adl>!Actions>Correct WFS RF offsets button to remove offsets in all the RF demodulated signals. I have set this button to use /opt/rtcds/caltech/c1/Git/40m/scripts/RFPD/resetOffsets.py script.

At this point, we are ready to see if we have WFS sensitivity but I need to work on other projects today and Yuta and Paco took over interferometer for 60 Hz noise hunting.

Attachment 1: YARM_WFS_MASTER.png
Attachment 2: PXL_20230203_211014833.jpg
17448   Sat Feb 4 14:55:25 2023 AnchalUpdateASCDC sensing matrix for AS WFS for YARM

### Filter and scripts setup

I copied IOO_WFS1_I filter bank to AWS_WFS1/2_I/Q filter banks to copy the dewhitening and 60comb filters. Then I turned them on.

Similarly, I copied IOO_WFS1_PIT filter bank to AWS_YARM/XARM_WFS1/2_PIT/YAW filter banks. I created a generalised script to handle all WFS on/off.hold/onfromhold operations here. I also generalized toggleWFSoffsets script to be used for measuring DC sensing matrix.

### DC sensing matrix measurement

This measurement folllowed the method used by Koji in 40m/17354. The measurement is pushed here. Ntoe that when using this method, while the test finishd in ~1000 seconds, it takes dtt >20 min to retrieve the timeseries data from DQ channels. Thisis weird because cdsutils.getdata does not have this lag. If anyone knows why this is the case, it would be helpful in making this method faster.

• Locked YARM and misaligned ITMX and ETMX
• Centered the AS beam on WFS using DC value.
• Ran ASS on YARM to get to best aligned cavity state.
• Unlocked YARM and ran C1AWS_YARM_WFS_MASTER>!Actions>Correct WFS RF offsets to zero teh offsets.
• Locked YARM again and waited for >120 seconds.
• Ran python /opt/rtcds/caltech/c1/Git/40m/scripts/AWStoggleWFSoffsets.py AWS BOTH -a YARM -t 120
• Measurement start time: 04/02/2023 22:37:00 UTC
• The offset values required for step response test above were determined by trying out values and making sure that transmission does not go down by more than 15%.
• I had to leave by 3:30 pm, so I couldn't complete the analysis of measured data.I'll post data here soon.

Additions Sun Feb 5 18:06:54 2023:

### Data analysis

I got the step response data using cdsutils.getdata and measured the sensing matrix and took and inverse with error propagation. Attachment 1 page 1 shows the raw data measured. Then the data was segmented based on step response time data and a linear fit is used to get linear trend of each channel in null configuration. This is used to remove bias later while measuring the step heights in each sensor. Page 2 shows this data. Page 3 shows final detrended and normalized step response data that was used to measure the sensing matrix. It came out to be:

YARM WFS DC Sensing Matrix

        ITMY PIT         ETMY PIT         ITMY YAW         ETMY YAW
1.94 +/- 0.02    0.83 +/- 0.07   -0.15 +/- 0.04      1.3 +/- 0.1  to WFS1 PIT
5.62 +/- 0.05      8.8 +/- 0.2     -0.2 +/- 0.1      2.5 +/- 0.2  to WFS2 PIT
-0.43 +/- 0.03   -1.13 +/- 0.07    1.51 +/- 0.04     -0.9 +/- 0.2  to WFS1 YAW
-1.42 +/- 0.05     -7.1 +/- 0.2      3.3 +/- 0.1    -19.5 +/- 0.4  to WFS2 YAW


Taking it's inverse with uncertainties supported matrix inverse function gave following output matrix to be used:

YARM WFS Estimated Output Matrix
        WFS1 PIT         WFS2 PIT         WFS1 YAW         WFS2 YAW
0.628+/-0.022   -0.031+/-0.007   -0.027+/-0.020    0.039+/-0.004  to ITMY PIT
-0.431+/-0.020    0.146+/-0.007   -0.002+/-0.018 -0.0099+/-0.0030  to ETMY PIT
-0.086+/-0.031    0.078+/-0.010    0.728+/-0.029   -0.029+/-0.008  to ITMY YAW
0.097+/-0.009 -0.0377+/-0.0030    0.126+/-0.008 -0.0555+/-0.0020  to ETMY YAW

Attachment 1: YARM_WFS_DC_Sensing_Matrix_Step_Response_Test.pdf
17453   Mon Feb 6 20:44:34 2023 AnchalUpdateASCYARM WFS First Attempt - Success

I uploaded this measured output matrix to the YARM WFS model:

 Quote: YARM WFS Estimated Output Matrix  WFS1 PIT WFS2 PIT WFS1 YAW WFS2 YAW 0.628+/-0.022 -0.031+/-0.007 -0.027+/-0.020 0.039+/-0.004 to ITMY PIT -0.431+/-0.020 0.146+/-0.007 -0.002+/-0.018 -0.0099+/-0.0030 to ETMY PIT -0.086+/-0.031 0.078+/-0.010 0.728+/-0.029 -0.029+/-0.008 to ITMY YAW 0.097+/-0.009 -0.0377+/-0.0030 0.126+/-0.008 -0.0555+/-0.0020 to ETMY YAW 

Then I played witht the signs of the gains and their values in the C1:AWS-YARM_WFS1/2_PIT/YAW filter banks until I saw a correct response for steps on ETMY and correction within 10-20 s.

I measured the OLTF of the loops with noise injection in each loop simultaneously. This test takes ~10 min. Except for the WFS2 YAW loop, all other loops behaved as expected with UGFs in WFS1 PIT 0.02 Hz, WFS1 YAW 0.04 Hz, and WFS2 PIT 0.035 Hz.

I left this state On for 1 hour and the YARM retained transmission. Attachment 2 shows the history.

Then I conducted another toggle test to see how the step response is. Attachment 3 shows the same results as last post for the new output matrix. Note high sensitivity of WFS2 YAW signal to PIT actuations. The worst row was for WFS2 YAW degree as expected (see page 3 attachment 3).

The new calculated output matrix (after product with the existing matrix) is:

YARM WFS Estimated Output Matrix

        WFS1 PIT         WFS2 PIT         WFS1 YAW         WFS2 YAW
0.70+/-0.05    0.011+/-0.014   -0.203+/-0.032   -0.093+/-0.010  to ITMY PIT
-0.42+/-0.04   -0.111+/-0.010    0.025+/-0.025    0.019+/-0.007  to ETMY PIT
-0.00+/-0.05   -0.091+/-0.016      0.76+/-0.04    0.041+/-0.013  to ITMY YAW
0.201+/-0.022    0.062+/-0.007    0.244+/-0.015    0.067+/-0.005  to ETMY YAW

With this matrix in, I had to change all gain signs to negative and teh loop was stable to my kick test on ITMY and ETMY on both PIT and YAW DOFs. OLTFs can be tuned further. Maybe later, I'll do another toggle testin hope of getting an identity matrix.

Attachment 1: YARM_WFS_OLTF.pdf
Attachment 2: YARM_WFS_First_Attempt_1hr_history.pdf
Attachment 3: YARM_WFS_DC_Sensing_Matrix_Step_Response_Test_1359774014.pdf
17454   Tue Feb 7 11:12:44 2023 ranaUpdateASCYARM WFS First Attempt - Success

It would be great if you could calibrate these ASC channels into physical units (e.g. urad or nrad). I am curious to see how the noise spectra compares to the IMC WFS.

Since the data is still on disk, you can probably use the oplev channels to calibrate the WFS. Also, you can calibrate either WFS or oplev by moving the SUS alignment sliders until the arm power goes down by sqrt(2) or 2.

To get data faster with DTT, I ask only for data sampled at 16 Hz. You can either just read the EPICS channels (OUT16) or ask DTT for a BW=16 Hz for the fast channels. No need for high sample rate for step response plots.

17456   Wed Feb 8 12:25:42 2023 AnchalUpdateASCYARM WFS Loop Step Response

I did a quick step response test today with YARM WFS loops running. Steps were put in as offsets in channels C1:SUS-I/ETMY_ASCPIT/YAW_OFFSET to not let transmission go below 0.6-0.7 out of 1. I waited 30 seconds between each step by simply running sleep 30 on my terminal. Once finished, dtt still was taking a long time to get recently measured data even for 16 Hz channels. I used cdsutils getdata to get the measurement and calculate time constants for each loop. Time constant is defined by the time it took for C1;SUS-I/ETMY_ASCPIT/YAW_OUT16 channel to come to 1/e of the offsetted value. Inverse of this time constant is also printed as text on the plot. Note that I redid step on ETMY PIT as the first pass seemed not strong enough to me. See attachment 2 for settings.

The Pit loops seem to be bit faster with about 5s time constant while YAW loops have about 10s.

Attachment 1: YARM_WFS_Loop_Step_Response_1359920994.pdf
Attachment 2: Screenshot_2023-02-08_12-30-21.png
17465   Wed Feb 15 12:07:35 2023 AnchalUpdateASCASC model updated to take inputs from IMC WFS

I have updates the ASC model inside c1ioo.mdl file to take inputs from IMC WFS when selected with AS option (on the left side of AS WFS block. I've also implemented the missing lockin option in this model. Currently the old AWS model is still in c1ioo which will be removed once we have successfully used the new ASC model for locking AS WFS loops for YARM. Now ETMX and ETMY QPD signals are also available in the input matrix for use and available outputs are ETMs, ITMs, BS, PRM, and SRM.

While changing these models, I also removed use of RFM model in ASC as this is not required anymore. The IPC from any model to any model can be done directly now. Overtime, c1rfm would be retired by removing one channel connection at a time.

Attachment 1: Screenshot_2023-02-15_12-09-10.png
17484   Sun Feb 26 00:13:55 2023 AlexConfigurationASCIOO MC PIT/YAW gain change

The following changes were made to the WFS MASTER IMC Pitch and Yaw gains:

Gain values for the pitch and yaw on MC1, MC2, and MC3 filters on the SUS ASC inputs have been carried over to the WFS MASTER output filters.
This was done such that Tomohiro and I could take AC measurements at an oscillation freq of 77 Hz on the pitch and yaw mirrors, while being sure that the amplitude of the AC signal being applied to each mirror is the same. The filters on the WFS output will have gains changed from 1.0 to the previously mentioned calibration values described in ELOG 17481

The values calculated for each filter were inverses of the callibration constants. The filters at the SUS ASC inputs were modified to read gain values of 1.0 again.
See the table bellow for the values passed to each filter.
In summary:
originally IOO-MC1,2,3_PIT/YAW_GAIN = 1.0. Now:

MC1,2,3_ASCPIT/ASCYAW_GAIN >>  IOO-MC1,2,3_PIT/YAW_GAIN

IOO-MC1,2,3_PIT/YAW_GAIN >> 1.0

387   Thu Mar 20 17:45:36 2008 ranaSummaryASSAdaptive Filtering in the ASS system
Over the past couple weeks we (Matt, Alex, Rob, me) have worked on getting an adaptive filter
system working. We wanted to load this system into c1ass to use this processor. The dither alignment
system hasn't been employed here for awhile and so we have just used this box.

The signals are acquired in the PEM ADCU. Alex modified the code there to send the signals over to
the new system. We also get the SUS-LSC_OUT signals from each of the suspensions so that we can
try to minimize them.

The outputs of the adaptive filter go into the unused SUS-MCL inputs of all the suspensions (except
for MC2). In the current setup, we have 6 accelerometers and 1 seismometer around the MC to be used
to demonstrate the principle of the whole thing.

Much more documentation and description of everything is necessary. We'll try to get Matt, Rob, and Alex
to use the elog.
428   Fri Apr 18 19:46:08 2008 ranaUpdateASScheck adaptive
I restarted the adaptive code today using 'startass' and 'upass'.
I moved them into the scripts/ASS/ subdirectory.

Things seem OK. With a MU=0.03 and a TAU=0.00001, there is a still
a good factor of 10 reduction of the 3 Hz stack peak from the MC2
drive by doing FF into MC1.

I edited the ASS-TOP screen so that we could see such small numbers. I
also re-aligned the MC SUS to match the input beam (mainly MC3). The
cavity was locking on a TEM10 mode mostly -- we should look in the SUS
OSEM trends to see if MC3 has moved a lot in the last month or so.

Caryn Palatchi (a Caltech undergrad who just started working with us)
illustrated to me today that using even 1000 FIR taps is not very effective
for low frequency noise cancellation if you have a 2048 Hz sample rate. More
precisely, the asymptotic Wiener filter which our 'LMS' algorithm converges
to, can often amplify the noise at frequencies below f_sample/N_taps.

A less obvious thing that she also noticed is that there is almost no cancellation
of the 16.25 Hz bounce mode when using such a short filter. That's because that
mode is fairly high Q: the transfer function from the Z-ACC to the cavity signal
goes through the high-Q vertical suspension resonance; the FF signal we send back
goes through the low-Q horizontal pendulum response only. Therefore the filter
needs to be able to simulate ~100 cycles at 16.25 Hz in order to cancel that peak.

Duh.

The message here is: we need to find a computationally efficient way to do FIR filtering
or its not going to ever be cool enough to help us find the Crab.
Attachment 1: 0052_xray_thm45.jpg
432   Mon Apr 21 12:58:42 2008 robUpdateASScheck adaptive

 Quote: Caryn Palatchi (a Caltech undergrad who just started working with us) illustrated to me today that using even 1000 FIR taps is not very effective for low frequency noise cancellation if you have a 2048 Hz sample rate. More precisely, the asymptotic Wiener filter which our 'LMS' algorithm converges to, can often amplify the noise at frequencies below f_sample/N_taps. A less obvious thing that she also noticed is that there is almost no cancellation of the 16.25 Hz bounce mode when using such a short filter. That's because that mode is fairly high Q: the transfer function from the Z-ACC to the cavity signal goes through the high-Q vertical suspension resonance; the FF signal we send back goes through the low-Q horizontal pendulum response only. Therefore the filter needs to be able to simulate ~100 cycles at 16.25 Hz in order to cancel that peak. Duh. The message here is: we need to find a computationally efficient way to do FIR filtering or its not going to ever be cool enough to help us find the Crab.

This is the reason for "RDNSAMP" parameter in the ASS code. The FIR filtration is applied at the downsampled rate, not the machine rate. So, if RDNSAMP=32, the effective sampling rate of the FIR filter is 64Hz, and thus noise cancellation should be good down to 64Hz/1000, or 64mHz, and the filter has an impulse response time that extends to 15 secs. I'm not convinced the filter length is what's limiting the performance at the bounce mode, but I agree that a faster FIR implementation would be good.
579   Thu Jun 26 21:07:11 2008 ranaConfigurationASSdust & MC1
I realized today, that yesterday while we were trying to debug the adaptive noise canceler, I turned
off the analog dewhitening on MC1. I did this by changing settings on the Xycom screen but I
forgot to elog this -- this may have caused problems with locking via increased frequency noise.
I have now returned it to its nominal, dewhitening on, configuration.

I also used mDV to look at the last year of dust trend. I have plotted here the cumulative
histogram in percentile units of the 0.5 micron dust level. The x-axis is in units of particles per cu. ft.
and the y-axis is percentage. For example, the plot tells us that over the last year, the counts were
below 6000, 90% of the time. I have set the yellow and red alarm levels to alarm at the 95-th and 99-th
percentile levels, respectively.
Attachment 1: Screenshot-2.png
981   Mon Sep 22 21:54:05 2008 ranaUpdateASSNew Wiener result with x10 gain in ACC
The 2 attached PDF files show the performance of the Wiener filter code on 2 hours of data
with a 4000 tap filter on 64 Hz data. All 6 accelerometers around the MC and the Ranger seismometer
were used.

I attribute the improved performance in the 3-10 Hz band to the better SNR of the ACC channels. To
do better below 1 Hz we need the Guralps.
Attachment 1: f.pdf
1105   Sun Nov 2 20:44:58 2008 ranaUpdateASSWiener Filter performance over 5 hours
I took one 2 hour stretch of data to calculate a MISO Wiener filter to subtract the Ranger seismometer
and the 6 Wilcoxon accelerometers from the IOO-MC_L channel. I then used that static filter to calculate
the residual of the subtraction in 10 minute increments for 5 hours. The filter was calculated based upon
the first 2 hours of the stretch.

The MC lock stretch is from Oct 31 03:00 UTC (I think that we are -8 hours from UTC, but the DST confounds me).
So its from this past Thursday night.

I wrote a script (/users/rana/mat/wiener/mcl_comp.m) which takes the static filter and does a bunch of loops
of subtraction to get a residual power spectrum for each 10 minute interval.

In the attached PNG, you can see the result. The legend is in units of minutes from the initial t0 = 03:00 UTC.

BLACK-DASHED -- MCL spectrum before subtraction

I have also used dashed lines for some of the other traces where there is an excess above the unsubtracted data.
Other than those few times, the rest are all basically the same; this indicates that we can do fine with a very
slow adaptation time for the feed-forward filters
-- a few hours of a time constant is not so bad.

After making the plot I noticed that the Ranger signal was totally railed and junky during this time.
This probably explains the terrible performance below 1 Hz (where are those Guralps?)

The second attached image is the same but in spectrogram form.
Attachment 1: f.png
Attachment 2: f1.png
1111   Mon Nov 3 22:35:40 2008 ranaUpdateASSWiener Filter performance over 5 hours
To speed up the Wiener filter work I defined a 256 Hz version of the original 16kHz IOO-MC_L signal. The
attached plots show that the FE decimation code works correctly in handling the anti-aliasing and
downsampling as expected.
Attachment 1: DAQ.pdf
1112   Tue Nov 4 00:47:53 2008 ranaUpdateASSWiener Filter performance over 5 hours
Same as before, but now with a working Ranger seismometer.

In the spectrogram, the color axis is now in dB. This is a whitened spectrogram, so 0 dB corresponds to
the average (median) subtraction. The color scale is adjusted so that the large transients are saturated
since they're not interesting; from the DV trend its some kind of huge glitch in the middle of the
night that saturated the MC1 accelerometers only (maybe a pump?).

The attached trend shows the 5 hours used in the analysis.
Attachment 1: f2.png
Attachment 2: f.png
1985   Fri Sep 11 17:11:15 2009 SanjitUpdateASSOAF: progress made

[Jenne & Sanjit]

Good news: We could successfully send filtered output to MC1 @ SUS.

We used 7 channels (different combinations of 3 seismometer and six accelerometer)

We tried some values of \mu (0.001-0.005) & gain on SUS_MC1_POSITION:MCL and C1ASS_TOP_SUS_MC1 (0.1-1).

C1:ASS-TOP_SUS_MC1_INMON is huge (soon goes up to few times 10000), so ~0.1 gains at two places bring it down to a reasonable value.

Bad news: no difference between reference and filtered IOO-MC_L power spectra so far.

Plan of action: figure out the right values of the parameters (\mu, \tau, different gains, and may be some delays), to make some improvement to the spectra.

** Rana: there's no reason to adjust any of the MCL gains. We are not supposed to be a part of the adaptive algorithm.

2434   Sun Dec 20 21:39:40 2009 rana, jenne, kiwamuUpdateASSOAF Model update and build instructions

### After a lot of headache, I got the OAF working again - read on for details.....................

Sometime last week, Jenne, Kiwamu, and I tried to update the OAF model to include the IIR "feed-around" path.

This path is in parallel to the existing FIR-based adaptive FXLMS stuff that Matt put in earlier. The reason for the

new path is that we want to try emulating the same FF technology which has been successful lately at LLO.

However, we were unable to make the ASS work after this work. Mostly, the build stuff worked fine, but we couldn't get DTT

to make a transfer function. The excitation channels could be selected and the excitation would actually start and get all the

way into MC1, but DTT would just hang on the first swep-sine measurement with no time-out error. Clearly our ASS building

documentation is no good. We tried using the instructions that Koji gave us for AAA, but that didn't completely work.

In particular, the 'make-uninstall-daq-ass' command gave this command:

[controls@c1ass advLigo]$make uninstall-daq-ass grep: target/assepics/assepics*.cmd: No such file or directory Please make ass first make: *** [uninstall-daq-ass] Error 1 re-arranging the order to do 'make-ass' first fixes this issue and so I have fixed this in the OAF Wiki. The there's the whole issue with the tpchn_C3.par file. This contains all the test point definitions for the ASS/OAF machine. The main IFO numbers are all in tpchn_C1.par and the OMC is all in tpchn_C2.par. When we do the usual build, in the 'make install-daq-ass' part: [controls@c1ass advLigo]$ make install-daq-ass
Installing GDS node 3 configuration file
/cvs/cds/caltech/target/gds/param/tpchn_C3.par
Updating DAQ configuration file
/cvs/cds/caltech/chans/daq/C1ASS.ini

we get this .par file installed in the target area. The ACTUAL param file seems to actually be in /cvs/cds/caltech/gds/param  !!

Of course, it still doesn't work. That's because the standard build likes to point to /cvs/cds/caltech/gds/bin/awgtpman and the one that runs on

linux is actually /opt/gds/awgtpman. So I've now made a file called startup_ass.cmd.good which runs the correct one. However, the default build

will try to start the wrong one and we have to fix the 'startass' script to point to the correct one on each build. Running the correct awgtpman

allows us to get the TP data using tools like tdsdata, so far no luck with DTT.\

UPDATE (23:33): It turns out that it was my old nemesis, NTPD. c1ass had a /etc/ntp.conf file that was pointing at an ntp server called rana113. I

am not an NTP server; I don't even know what time it is. I have fixed the ntp.conf file by making it the same ass c1omc (it now points to nodus). After

this I set the date and time manually (sudo date -s "20 DEC 2009 23:27:45") and then restarted NTPD. It should now be fine even when

we reboot c1ass.

After all of this nonsense, I am able to get TP data from c1ass and take transfer functions between it and the rest of the world !

2437   Mon Dec 21 02:22:31 2009 rana, jenne, kiwamuUpdateASSOAF Model update and build instructions

This allowed measuring the MC1 -> MCL TF finally. Its mostly flat. Data saved as Templates/OAF/OAF-MCLTF.xml

Attachment 1: Untitled.png
2438   Mon Dec 21 07:30:58 2009 ???UpdateASSOAF Model update and build instructions

What does OAF stand for? The entry doesn't say that. Also the acronym is not in the abbreviation page of the wiki.

2440   Mon Dec 21 10:09:06 2009 jenneUpdateASSOAF Model update and build instructions
OAF stands for Online Adaptive Filtering. We use the same computer which was once the ASS. One of these days, we'd like to completely be rid of all things which refer to ASS, and make even the computer's name OAF.
2441   Mon Dec 21 19:24:29 2009 ranaUpdateASSOAF Model update and build instructions

I fit the MC1 -> MCL TF using vectfit4.m (from mDV). The wrapper file is mDV/extra/C1/ fitMC12MCL.m.

Plotted here are the data (RED), the fit (BLUE), and the residual x10 (GREEN).

For the magnitude plot, residual is defined as ------   res = 1 - fit / data

For the phase plot the residual is defined as -------    res =  phase(data)-phase(fit)

You can see that the agreement is very good. The phase match is better than 5 deg everywhere below 10 Hz.

This TF is so smooth that we could have probably done without using this, but its good to excercise the method anyway.

Attachment 1: mc12mcl.png
2442   Tue Dec 22 02:50:09 2009 rana, kiwamu, jenneUpdateASSOAF Feedaround ON and doing something good

Kiwamu made the OAF screen functional today - screenshot attached.

After this, I used the measured TF of the MC1 to MCL to filter the signals from the Wilcoxon accelerometers and feed them into the MC.

The noise at 3 Hz went down by a factor of ~3. There's a little excess created at 100 Hz. Its good to see that our intuition about feed-forward is OK.

I did all of the filter calculations by adapting the scripts that Haixing, Valera, and I got going at LLO. They're all in the mDV/extra/C1 SVN.

The Wiener code predicts much better performance from using more than just 2 horizontal accelerometers, but I was too lazy to do more channels today.

I also added the Rai box to the Ranger readout today - the noise at 0.1 Hz went down by a factor of 10 and the noise at 1 Hz is close to 10^-11 m/rHz.

Attachment 1: oaf.png
Attachment 2: oaf.png
2449   Wed Dec 23 17:33:14 2009 ranaUpdateASSOAF Feedaround ON and doing something good

The Rai box ran out of batteries a couple of days ago and so the data is no good. I've put the Ranger back on the SR560 for now (but with the damping resistor removed, so the gain is 2x more than before).

4696   Wed May 11 23:02:52 2011 valeraUpdateASSDither angular stabilizitaion system update

This is what was done in past two days:

- The ETMY and ITMY pitch and yaw dofs are modulated at 40, 44, 42, 46 Hz respectively (oscillator A=30). The c1ass lockin numbers are 12, 14, 27, 29.

- The NAS55I signal is demodulated at the above frequencies. The demodulated I/Q signal phase is set to shift all signal into I-phase. The lockin inputs are bandpassed around respective frequency f with butter("Bandpass",2,f-0.5,f+0.5). The demod signals are then additionally low passed with butter ("Lowpass",4,0.5) so the servo ugf has to be below 0.5 Hz. The servo filter is p:z 0.0001:0.1.

- The ETMY demodulated signal is fed back to ITMY and visa versa.

- With the above 2x2 servo running we moved the input beam PZTs by hand to follow the cavity.

- At the end we offloaded the servo control signals to the SUS biases again by hand.

- The beam spot centering was estimated by unbalancing the ETMY/ITMY pitch/yaw coil combinations intentionally by 5%, which produces 1.3 mm shift of the node, and comparing the response to the residual signals.

- The dof set up currently is: ETMY pitch lockin 12 -> dof2, ITMY pitch lockin 14 -> dof4, ETMY yaw lockin 27 -> dof7, ITMY yaw lockin 29 -> dof9

- The next step is to demodulate the TRY(X) and servo the input beam PZTs

4709   Fri May 13 00:39:53 2011 valeraUpdateASSc1ass update

Here the status of the dither alignment or c1ass:

- Both pitch and yaw centering on ETMY/ITMY were closed simultatenously with ugf of ~1/30 Hz.

- I made a medm screen with beam positions as measured by the dither system.The snapshot is attached. There are visual perimeter alarms (red box around the display) to warn about arm power being low or the dither lines not being on. The screen has a pull down menu with 4 scripts:

. assUp - sets up the gains, phases and matricies for the dither system (both the spot centering and the input beam alignment)

. assOn - turns on the dithers and servo - just the Y-arm centering part at the moment

. assOff - turns off the servo and dither lines

. assDitherOn - turns on the dither lines but does not turn on the servo

- All scripts are in scripts/ASS and the medm screen is in medm/c1ass/master/

Still to do:

- Commission the input beam and X-arm servos

- Make scripts for X-arm

Attachment 1: c1assqpds.jpg
4726   Mon May 16 11:47:59 2011 kiwamuUpdateASSc1ass update part II

The medm screen for c1ass started being modified to be more user-friendly.

The modification is still ongoing, but the goal is to make a screen which anyone can easily understand and play with.

Still to do : ( need a volunteer )

- Modification of the screens

- Commission the input beam and X-arm servos

- Make scripts for X-arm

- Measure the PZT mirrors' matrix for the translation and angle

 Quote from #4709 Here the status of the dither alignment or c1ass: Still to do: - Commission the input beam and X-arm servos - Make scripts for X-arm

4795   Wed Jun 8 16:41:48 2011 valeraUpdateASSX and Y arm dither alignment status

The current status of the dither alignment system:

- Both Xarm and Yarm alignment are working. The scripts are: scripts/autoDither/alignX(Y). Each script sets up the respective arm, turns on the dither lines and servos for 66 sec, offloads the control signals to TM alignment biases and PZT sliders in case of  Yarm, and to TM and BS alignment biases in case of Xarm, and finally turns off and clears the servo filters and turns off the dither lines.

- Jammie witnessed the final tests of both scripts - both X and Y arm power went up from 0.6-0.7 to close to 1 and the AS beam became symmetric. Also Jammie wanted me to leave the ETMY oplev in its current non-nominal but more stable state i.e. the oplev signals go to the ADC from the D010033 card not the D020432 one. The scripts can now run from the CONFIGURE medm screen.

- Both arms use signals derived from modulating ITM and ETM in pitch and yaw dofs and demodulating the arm power (TRX or TRY) and the cavity length signal (AS55I). The Yarm actuation has 8 dofs - pitch and yaw of the ITM, ETM, and two input beam PZTs so all the sensed dofs are controlled. The Xarm actuation has only 6 dofs - pitch and yaw of the ITM, ETM, and BS. The Xarm servo is set up to servo the beam position on the ETMX and the relative alignment of the cavity and the input beam. The ITMX spot position is unconstrained and provides the null test. The residual displacement on the ITMX is 0.2-0.3 mm in yaw and 0.9-1.0 mm in pitch. The I phases of the beam centering lockins, which are also the error points of corresponding DOF filters, are calibrated in mm by unbalancing the TM coils by known amount. The attached snap shot of the medm screen now has both X and Y arm calibrated beam spot positions and uncalibrated input beam indicators. The input beam angle and position signals can/should be calibrated by tapping the signals digitally and applying the proper matrix transformation - this will require the model change.

- Currently there is no lock loss catching in the model. We should add a trigger on arm power (or an equivalent mechanism) to turn off the inputs to prevent the spurious inputs.

Attachment 1: BeamPositionIndicators.png
6723   Thu May 31 01:20:41 2012 JenneUpdateASSASS filter outputs are non-zero with no input

I was looking a little at ASS, while Yuta was doing some Green transmitted DC PD work, and I find that the output of some filters is totally insane with no deliberate input or excitation signals.

Note in the figure that the filter (which is a 2nd order butter bandpass in the C1:ASS-LOCKIN29_SIG filter bank) is ringing a lot - this needs fixing.  But, more disconcertingly, sometimes (not every time) the arm flashes, the input to the filter bank gets a ~1 sample long spike that is ~9,000,000 counts.  9 million is a lot of counts.  This is then making the filter go crazy.

Any ideas on how this can happen, and how we can stop / fix it?  It's certainly a CDS issue, but I'm not sure where or how.

Attachment 1: ASS_Yarm_crazyOutputs_30May2012.png
6980   Tue Jul 17 11:28:29 2012 JenneUpdateASSNames of DoF filters in ASS wrong

The names of the DoF filters in the ASS loop were wrong.  The filters themselves were correct (low pass filters at super low freq, for the Lock-in), but the names were backward.

Our convention is to name filters "poles:zeros", but they had been "z:p".  The names of FM1 in all the DoF filter banks are now fixed.

7017   Tue Jul 24 03:14:13 2012 JenneUpdateASSCalibration of MC ASS lockins

I wanted to check that the calibration of the MC ASS lockins was sensible, before trusting them forevermore.

To measure the calibration, I took a 30sec average of C1:IOO-MC_ASS_LOCKIN(1-6)_I_OUT with no misalignment.

Then step MC1 pitch by 10% (add 0.1 to the coil output gains).  Remeasure the lockin outputs.

2.63 / (Lockin1noStep - Lockin1withStep) = calibration.

Repeat, with Lockin2 = MC2 pit, lockin3 = MC3 pit, and lockins 4-6 are MC1-3 yaw.

The number 2.63 comes from: half the side of the square between all 4 magnets.  Since our offsets are in pitch and yaw, we want the distance between the line connecting the lower magnets and the center line of the optic, and similar for yaw.  Presumably if all of the magnets are in the correct place, this number is the same for all magnets.  The optics are 3 inches in diameter.  I assume that the center of each magnet is 0.9mm from the edge of the optic, since the magnets and dumbbells are 1.9mm in diameter. Actually, I should probably assume that they're farther than that from the edge of the optic, since the edge of the dumbbell ~touches the edge of the flat surface, but there's the bevel which is ~1mm wide, looking normal to the surface of the optic.  Anyhow, what I haven't done yet (planned for tomorrow...) is to figure out how well we need to know all of these numbers.

We shouldn't care more than ~100um, since the spots on the optics move by about that much anyway.

For now, I get the following #'s for the calibration:

Lockin1 = 7.83

Lockin2 = 9.29

Lockin3 = 8.06

Lockin4 = 8.21

Lockin5 = 10.15

Lockin6 = 6.39

The old values were:

C1:IOO-MC_ASS_LOCKIN1_SIG_GAIN = 7
C1:IOO-MC_ASS_LOCKIN2_SIG_GAIN = 9.6
C1:IOO-MC_ASS_LOCKIN3_SIG_GAIN = 8.3
C1:IOO-MC_ASS_LOCKIN4_SIG_GAIN = 7.8
C1:IOO-MC_ASS_LOCKIN5_SIG_GAIN = 9.5
C1:IOO-MC_ASS_LOCKIN6_SIG_GAIN = 8.5

The new values measured tonight are pretty far from the old values, so perhaps it is in fact useful to re-calibrate the lockins every time we try to measure the spot positions?

7074   Wed Aug 1 22:37:21 2012 JenneUpdateASSFilters installed in the ASS

As part of trying to figure out what is going on with the ASS, I wanted to figure out what filters are installed on which lockins.

Each "DoF"(1-6) has a zpk(0.1,0.0001,1)gain(1000), which is a lowpass with 60dB of gain at DC, and unity gain at high frequencies.

For the lockins, since there are so many, I made a spreadsheet to keep track of them (attached).

So, what's the point?  The point is, I think that all of the LOCKIN_I filter modules should be the same, with a single low pass filter.  The Q filter banks don't matter, since we don't use those signals, and the signals are grounded inside the model.  The phase of each lockin was / should be tuned such that all of the interesting signal goes to I, and nothing goes to Q.  The SIG filter modules seem okay, in that they're all the same, except for their band pass frequency.  I just need to check to see what frequency the ASS scripts are trying to actuate at, to make sure we're bandpassing the correct things.

Attachment 1: ASS_lockin_filters_1Aug2012.pdf
7075   Thu Aug 2 00:43:55 2012 JenneUpdateASSMajor cleanup of the ASS model

[Jamie, Jenne]

We are trying to figure out what the story is with the ASS, and in order to make it more human parse-able, we cleaned up the c1ass.mdl.

So far, we have made no changes to how the signals are routed.  The local oscillators from each lockin still get summed, and go directly to the individual optics, and the demodulated signals from each lockin go through the sensing matrix, the DoF filters, then the control output matrix, and then on to the individual optics.  So far, so good.

Much of the cleanup work involved making a big library part, which is then called once for PIT and once for YAW in the ass top level, rather than have 2 code-copies, which give Jamie conniptions.  Inside the library part GoTo and From tags were used, rather than having all the lines cross over one another in a big spaghetti mess.

One of the big actual changes to the ass was some name changes. Rather than having mysterious "ASS-LOCKIN(1-30)", they are now named something like "ASS-PIT_LOCKIN_ETMY_TRY", indicating that this is in the pitch set, actuating on ETMY, and looking at TRY for the demodulated signal.  The "DOF" channels are similar to what they were, although we would like to change them in the future.....more on this potential change later.  Previously they were "ASS-DOF(1-10)", but now they are "ASS-PIT_DOF(1-5)" and "ASS-YAW_DOF(1-5)". This channel naming, while it makes things make more sense, and is easier to understand, means that all of the ASS scripts need to be fixed.  However, they all needed updating / upgrading anyway, so this isn't the end of the world.

This channel name fixing also included updating names of IPC (shmem/dolphin/rfm things) blocks, which required matching changes in the SUS, RFM and LSC models.  All 4 models (ASS, SUS, RFM, LSC) were recompiled and installed.  They all seem fine, except there appears to be a dolphin naming mismatch between OAF and SUS that showed up when the SUS was recompiled, which presumably it hadn't been in a while.  We need to figure this out, but maybe not tonight.  Den, if you have time, it would be cool if you could take a look at the OAF and SUS models to make sure the names match when sending signals back and forth.

______________________

We also had a long chat about the deeper meaning of the ASS.

What should we be actuating on, and what should we be sensing?  A potential thought is to rename our DOF channels to actual DoF names: input axis translation, input axis angle, cavity axis translation, cavity axis angle.  Then actuate the dither lines on a cavity degree of freedom, sense the influence on TRX, TRY and an LSC PD (as is currently done), then actuate on the cavity degree of freedom.

Right now, it looks like the actuation is for individual optics, the sensing is the influence on TRX, TRY and an LSC PD, then actuate on a cavity degree of freedom.  So the only change with the new idea is that we actuate in the DoF basis, not the optics basis.  So the Lockin local oscillators would go through the control output matrix.  This makes more sense in my head, but Jamie and I wanted to involve more people in the conversation before we commit.

The next question would be: how do we populate the control output matricies?  Valera (or someone) put something in there, but I couldn't find anything on the elog about how those values were measured/calculated/came-to-be.  Any ideas?  If we want to dither and then push on isolated degrees of freedom, we need to know how much moving of which optics affects each DoF.  Is this something we should do using only geometry, and our knowledge of optic placements and relative distances, or is this measurable?

7081   Thu Aug 2 23:31:04 2012 JenneUpdateASSMajor cleanup of the ASS model

Jamie re-redid the ASS model a few hours ago.

I have just compiled it, and restarted c1ass.  (The model from last night is currently called c1ass3.mdl)  I had to delete and re-put inthe goto and from tags for the LSC signal coming in from the shmem.  For some reason, it kept claiming that the inputs using the from tags were not connected, even when I redid the connections.  Finally deleting and dragging in new goto and from tags made the model happy enough to compile.  Whatever.  I'm going to let Jamie do the svn-ing, since he's the one who made the changes.  Before I had figured out that it was the tags, I was concerned that the shmem was unhappy, so there was no signal connecting to the input of the goto tag, and that was somehow bad....anyhow, I recompiled the LSC model to re-create the shmem sender, but that had no effect, since that wasn't the problem.

The change from last night is that now the library parts are by DoF.  There is only one matrix in each library part, before the servo filters. Now we can DC-actuate on a single mode (ETM or ITM, pitch or yaw), and see how it affects all 4 sensors (the demodulated signals from the lockins). We need to measure the sensing matrix to go from the several sensors to the servo input.

7082   Fri Aug 3 03:24:13 2012 JenneUpdateASSNew ASS screens

I wanted to try out the ASS tonight, but I wanted some kinds of screens thrown together so I would know what I was doing.  Turns out screens take longer than I thought.  Am I surprised? Not really.

They're probably at the ~85% mark now, but I should be able to try out the ASS tomorrow I think.

7092   Mon Aug 6 17:15:15 2012 JenneUpdateASSFilter banks not working

I was trying to load some filters into the ASS so that I can try it out, but for some reason the filter banks aren't working - clicking the on/off buttons doesn't do anything, filters (which exist in the .txt file generated by foton) don't load.

I've emailed cds-announce to see if anyone has any ideas.

7099   Tue Aug 7 00:22:10 2012 JenneUpdateASSFilter banks working

 Quote: I was trying to load some filters into the ASS so that I can try it out, but for some reason the filter banks aren't working - clicking the on/off buttons doesn't do anything, filters (which exist in the .txt file generated by foton) don't load. I've emailed cds-announce to see if anyone has any ideas.

When the network / fb went bad this afternoon, I had been working on the ASS model, shortening the names of the filter banks to fix the problem from elog 7092.  I wanted to finish working on that, so the ASS model is now rebuilt with slightly shorter names in the filterbanks (which fixes the problem of the filter banks not working).

------------------------------------------------------------

I mentioned this to Jamie the other day, but here's the error that you get when the GoTo/From tags aren't working:

>>rtcds make c1ass ### building c1ass... Cleaning c1ass... Done Parsing the model c1ass... IPC 9 8 is C1:LSC-ASS_LSC IPC 9 8 is ISHME IPC 10 9 is C1:RFM-LSC_TRX IPC 10 9 is IPCIE IPC 11 10 is C1:RFM-LSC_TRY IPC 11 10 is IPCIE INPUT XARM_LSC_in is NOT connected INPUT YARM_LSC_in is NOT connected ***ERROR: Found total of ** 2 ** INPUT parts not connected make[1]: *** [c1ass] Error 255 make: *** [c1ass] Error 1

I don't know why these tags weren't working, but there was a GoTo tag on the output of the LSC shmem block, and then Froms on each of the XARM_LSC_in and YARM_LSC_in.  The other day I played around with a bunch of different things (grounding inputs, terminating outputs, whatever), but finally replacing the tags with identical ones freshly taken from CDS_PARTS made it happy.

7100   Tue Aug 7 03:20:56 2012 JenneUpdateASSASS setup, on, off scripts written

I wrote new setup, on and off scripts for the arm ass.  They take the arm as an argument, so it's the same script for both arms.  Scripts are in ...../scripts/ASS/ , and have been checked in to the 40m svn.

So far the on script doesn't really do anything, since I haven't chosen values for the CLKGAINs of the lockins.  The old values were 30 for lockins 12, 14, 27, 29 and 250 for lockins 7, 9, 22, 24.  Unfortunately, I have no memory of which lockin means what in the old numbered system.  I'll have to look that up somehow.  Or, just dither the optics using some value and look at the spectrum to see the resulting SNR and just pick something that gives me reasonable SNR.

I modified the ASS model slightly:

* Added an overall gain to the ASS_DOF2 library part, between the matrix and the servo inputs so we can do soft startups.  Self - remember that the main ASS screen needs to be modified to reflect this!

* Rearranged the order that the demodulated signals go into the matrix.  I hadn't paid attention, and the old ordering had the transmission (TRX/TRY) demod signals interleaved with the LSC demod signals.  I've changed it to be all the TR signals, then all the LSC signals.  I think this makes more sense, since we will use these inputs separately, so now they're on different halves of the matrix.

7123   Wed Aug 8 20:34:29 2012 JenneUpdateASSTrouble measuring sensing matrix

I turned on the ASS, without closing the loops, to try to measure the sensing matrix.

The Yarm was locked (Eric did a nice job earlier - he'll ELOG ABOUT IT before he goes home!), and I used an LO CLKGAIN of 300 on all of the TRY Lockins.  Then I put on and took away a 10% offset in pitch, but it's almost impossible to see the difference.

The attached is a truly awful screenshot, but you can kind of see what's going on.  The big steps are me increasing the LO gain, but around "0" on the x-axis I changed the pitch offset from 10% away to nominal.  Since there are such big oscillations, the change is basically non-existent.  Grrrr. I'll look at it again tomorrow, since I have an exiting bike ride home ahead of me....

7124   Wed Aug 8 20:50:39 2012 KojiUpdateASSTrouble measuring sensing matrix

From the log, I couldn't understand what has been done.

The procedure we should perform is

1. Dither total 4 dofs of the two mirrors with different frequencies. Some fluctuation of TRY is even visible in dataviewer.
2. The cavity is aligned at the beginning. These 4 peaks in TRY in DTT is small or invisible. Some 2nd harmonics are visible.
3. Misalign one of the dofs. Some peaks get bigger.
4. Correspoding lockin output becomes bigger.

Then you can start measuring the sensing matrix. At which part did the attempt fail?

 Quote: I turned on the ASS, without closing the loops, to try to measure the sensing matrix.  The Yarm was locked (Eric did a nice job earlier - he'll ELOG ABOUT IT before he goes home!), and I used an LO CLKGAIN of 300 on all of the TRY Lockins.  Then I put on and took away a 10% offset in pitch, but it's almost impossible to see the difference.  The attached is a truly awful screenshot, but you can kind of see what's going on.  The big steps are me increasing the LO gain, but around "0" on the x-axis I changed the pitch offset from 10% away to nominal.  Since there are such big oscillations, the change is basically non-existent.  Grrrr. I'll look at it again tomorrow, since I have an exiting bike ride home ahead of me....

7129   Thu Aug 9 00:23:11 2012 JenneUpdateASSTrouble measuring sensing matrix

Quote:

From the log, I couldn't understand what has been done.

The procedure we should perform is

1. Dither total 4 dofs of the two mirrors with different frequencies. Some fluctuation of TRY is even visible in dataviewer.
2. The cavity is aligned at the beginning. These 4 peaks in TRY in DTT is small or invisible. Some 2nd harmonics are visible.
3. Misalign one of the dofs. Some peaks get bigger.
4. Correspoding lockin output becomes bigger.

Then you can start measuring the sensing matrix. At which part did the attempt fail?

 Quote:

Cavity started out aligned pretty well, but not 100%.  Transmission was ~0.8 . Perhaps this was part of the problem.

I realize now that you mention it, it was totally amateur hour of me to only look at the lockin outputs on StripTool (plus POY and TRY on Dataviewer), and not look at TRY on DTT...or any spectra at all.  Not so intelligent.  I could see some fluctuation of TRY on Dataviewer that corresponded to me turning on the oscillators, as well as the spot wiggling on the camera view of ETMYT a teeny bit.

When applying a 10% misalignment to ETMY Pit (by adding 0.1 to the Pit components of the output matrix, as is done in the MC spot position calibration), I could see that there was a small jump in the StripTool trace, but it was much smaller than the ambient fluctuations of the output.

I just looked back and realized that I must have forgotten to add my screenshot, but it's saved on a desktop on Rossa.  It would be better if I had attached the data, but from that you see that the average of the lockin output signal didn't change very much in the last several minutes of the measurement, but the fluctuations (no misalignment offsets) are pretty big, maybe ~10% or 15% the size of the signal.  Then when I added the misalignment to one mirror (ETMY PIT), there is a very small jump in the lockin signal, but it is much, much smaller than the size of the ambient fluctuations.  Perhaps a long average would result in a "real" value, but by looking by eye, I can't see a discernible difference in the average value of the lockin outputs.

My plan is to do as you say, dithering all 4 optics, and misaligning a single optic's single DoF (Pit or Yaw), and seeing how that misalignment affected each of the sensors (the lockin outputs).  Then put that DoF back to nominal, and misalign a different DoF, rinse and repeat.

Okay, so this is a little stream-of-consciousness-y, and you're going to think I'm really dumb, but I just realized that I haven't set the phase of the lockin demodulators yet.  So I think I need to dither the optics, and go through each of the sensors, and adjust the phase until the peak in TRY in DTT is maximized for the I phase, and minimized for the Q phase (since we use the I-output).  Bah.  Bad Jenne.

7131   Thu Aug 9 01:26:03 2012 KojiUpdateASSTrouble measuring sensing matrix

That's a good point, but I suspect that you end up with the in-phase (0deg) as the response of the IFO is immediate compared with the dithering frequency
as long as the whitening/dewhitening are properly compensated in the digital realm.

 Quote: Okay, so this is a little stream-of-consciousness-y, and you're going to think I'm really dumb, but I just realized that I haven't set the phase of the lockin demodulators yet.  So I think I need to dither the optics, and go through each of the sensors, and adjust the phase until the peak in TRY in DTT is maximized for the I phase, and minimized for the Q phase (since we use the I-output).  Bah.  Bad Jenne.

7135   Thu Aug 9 12:31:36 2012 JenneUpdateASSASS rebuilt again
I was (in between Eric's measurements) driving the YARM ASS dithers, and noticed that instead of driving ITMY PIT, I was driving ITMX PIT. I looked in the model, and when I re-did the model after an svn revert a few days ago, it looks like I got the shmem parts for the ITM PIT signals backwards. I have fixed that, rebuilt, installed and restarted the ass model.
7137   Thu Aug 9 23:50:09 2012 JenneUpdateASSASS matrix measured, first ASS test

Koji pointed out that I was being silly, and rather than actually misaligning the optics (by, say, changing their IFO Align sliders) I was changing the location of the actuation node by changing the coil output gains.  Now I see nice signals at the I_OUT of each of the demodulators (so far I've only looked at the YARM).

I've measured and inverted the matrix by taking the nominal values of the demodulator outputs when the optics are all by-hand optimally aligned, then one-by-one misaligning an optic's angle (pitch or yaw), and looking at the demod outputs that result.  Repeat with each misalignment DoF for each of the 4 rows of the matrix.  Then I set the pit/yaw coupling elements of the matrix to zero.  Then invert the matrix, put it in, and see what happens.  So far, the yaw DoFs converged to zero, but the pitch ones didn't.  I'll play with it more and think some more tomorrow.

8176   Wed Feb 27 00:56:01 2013 JenneUpdateASSMotivation for reactivating the ASS

I am putting a little bit of brain power into reviving the ASS, and I want to write down what the motivation is, and what the short and long-term plans are.

Why?

The IFO IR is not optimally aligned right now.  While we were at atmosphere, we should have taken the time to align the green beams to the arms until the greens were both resonating TEM00.  We were lazy, and excited to pump down, so we decided that locking on higher order modes was good enough to ensure the beams came out of vacuum.  Once we were pumped down, ITMY and ETMY were aligned to the green beam axis.  Then, the IR was aligned to this new Yarm cavity axis.  This would have been okay, and pretty close, if we had aligned the green beam all the way (used only the outside steering mirrors to resonate TEM00, after the cavity mirrors were aligned for flashing IR).  After the IR was aligned to the Ygreen axis, the rest of the IFO was aligned to this slightly-incorrect input pointing.  We want to measure the IR spot positions on ITMY and ETMY so that we can tweak the input pointing until we hit the center of both ITMY and ETMY.  Then we will align Ygreen's input pointing to this proper IR cavity axis.  The rest of the IFO alignment will also have to be redone.  This calls for a functioning A2L system, so the measurement part of the ASS.

The immediate motivation for measuring the spot positions is that the current Xarm IR axis is not at all very close to the Xgreen axis.  The other day while we were fixing up the Xend table (note in elog 8162), we found that the TRX beam to the TRX PD and the trans camera was clipped on the 2" harmonic separator (which is the first optic that the transmitted IR beam sees on the end tables).  It was clipping on the left side of the optic, if you are looking at the face of the optic.  This is the more east-erly side of the optic.  We moved that optic to the side so that we were not clipping.  Then, today when Manasa was trying to align the Xgreen beam, she found that it was clipping on the right side of the harmonic separator, the more west-erly side.  I remember seeing that the green beam was roughly centered on the harmonic separator when we were at atmosphere, so this clipping is certainly due to Yuta, Evan and my moving of the harmonic separator.  Since the end green steering optics are not very orthogonal in angle/translation, it is very difficult to translate the beam by a significant amount.  If we keep the current IR alignment, which surely isn't good anyway (you can see on the ETMXF camera that the beam isn't centered), we would probably have to move the Xgreen steering optics, which would be a total pain.  It seems that the better plan is to leave them where they are, and get the IR pointing in the correct direction, and move the harmonic separator back to where it was originally.

Short term (< few days):

Write the arm section of the existing MeasureSpotPositions.py script (in ....../scripts/ASS).  Write a wrapper script that, like ...../scripts/ASS/MC/mcassMCdecenter, calls sets up the lockins, runs MeasureSpotPositions.py, and calculates the calibrated spot positionsUse this information to hand tweak the input pointing, then realign the cavities to the new IR, and the greens to the new cavity axes.

All of the infrastructure for this is already in place in the c1ass model.   The only drawback to the current situation is the LSC output matrix only has one row for ASS, and so only one cavity can be measured at a time.  To make things faster, we could consider increasing the size of the LSC output matrix so that the 2 arms could be measured simultaneously.  This change is low priority for now.

Long term:

Make the full ASS system work.

A major change from the current situation is that the current ASS cannot actuate on the input pointing (TT1 and TT2 for Yarm, BS for Xarm).  We want a low bandwidth servo to force the input beam to follow the cavity axis.  Implementing this will require some changes to the ASS model.

Remeasure sensing matrix, test system.

ELOG V3.1.3-