It's not really helpful, because we don't yet have a solution, but here's the aLOG where this problem has been explored: LHO aLOG 31404. I have no suggestions as of yet on how to fix it, other than re-designing the loops to add more gain (read: *any* gain) at this frequency.

Hugh is studying how far back in time this problem has persisted (it's been a problem since at *least* Oct 28), in hopes to find some sort of coincident hardware/electronics activity to blame. But so far, no dice.

Jeff K, Sheila, Jenne, Evan

While we were having an EQ, we took a quick look at what is wrong with ITMY.  

Since Cheryl pointed out that this motion is seen in LF and RT, we became suspicous of a problem with top mass V and R damping.  Indeed, there was a "bounce" filter engaged in ITMY top mass V damping which must have been a mistake.  Once we turned this off the OLTF of the vertical damping looks verry similar between ITMX and ITMY.  With this filter on ITMY damping was garbage.  

I accepted the change in SDF. We also noticed while doing this that the top mass actuator state for ITMX was 1, while the rest of the quads were in state 2, so we switched that.  The large peak at 0.55 Hz that Cheryl aloged is gone now, and hopefully we won't have the problem with long long ringdowns on ITMY. 

Here is a summary of the activities including yesterday's and today's.

We have ...

• Adopted some matlab scripts as reported above and also below.
• Made the actual changes on the foton file namely H1CALCS.txt
• Loaded the new filters this morning at Nov. 21 18:24 UTC

This means that we have completed the update of the new suspension filters in CALCS.

[The new  CALCS actuator functions]

• It now uses the latest suspension tag model that Jeff updated 10 days ago (31432).
  • The latest includes the oplev damping.
  • Also, as shown in the attached screenshot in the above entry, the latest have slight difference around 1 Hz and some difference above 100 Hz.

More explicitly, the suspensions are extracted from the tagged model,

/ligo/svncommon/CalSVN/aligocalibration/trunk/Common/externals/SUSdynamModelTags/quadmodelproduction-rev8274_ssmake4pv2eMB5f_fiber-rev3601_h1etmy-rev7915_released-2016-11-11.mat

which is specified in H1's parameter file at:

/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER10/H1/params/H1params.conf

The DC values for the suspensions came a bit different than what Darkhan reported (31677) by a subpercent level. The matlab code reported the following values.

Ku  = 8.1642e-08 N/ct

Kp  = 6.8412e-10 N/ct

Kt  = -4.3891e-12 N/ct

We will double check with Darkhan to see what actually affected these values even thought the discrepancies aren't significant.

[Adjustment for quacking the filters]

When running the matlab script

/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER10/H1/Scripts/CALCS/quack_eyresponse_into_calcs.m

to update the actuator functions in CALCS, we ran into some problems for which we spent almost a day. This is a summary of what we encountered and how we mitigated.

• Issue 1: too many SOS sections in the TST stage
  • The TST stage ended up with too many SOS sections when using the latest tag model.
  • We relaxed the tolerance for minreal from 6e-5 to 1e-3 as a mitigation.
• Issue 2: violins not compatible with biquad form
  • Depending on the cut off frequency for excluding fine structures, quackcheck often reported a 0-gain error.
  • It turned out that this happens when the SOS filter coefficients don't have a b0i. We could not come up with a good mitigation.
  • We decided to set the cut off frequencies individually so that we can let all of them survive. The good values we found were: UIM cutoff = 1600 Hz and PUM cutoff = 2000 Hz.
• Issue 3: autoquack occasionally runs into a steady failure mode
  • Autoquack occasionally enters a situation where it keeps reporting BAD filter implementation for some reason.
  • We empirically found that we can get out of the situation by manually installing a simple and fake zpk filter once (e.g. zpk([], [], 19, "n") or similar ) at the filter module having the issue.
• Issue 4: c2d and minreal return some bad filters
  • c2d and minreal occasionally returned filters that are bad for quack (such as the number of zeros exceeding the number of poles).
  • This, for some reason, can be mitigated by running the script again.

Otherwise, we didn't change the code and therefore it did the processes that are describd in detail at 21322.

[Accuracy of the actuation functions in CALCS]

The first attachment is a plot showing the discrepancy between the desired and installed filters. UIM is the one who has the largest discrepancy in 10-100 Hz about a few % in magnitude and a few degrees in phase. Nevertheless, this shouldn't pose an issue for the resulting accuracy of DETAL_EXTERNAL as the UIM affects very weakly above 1 Hz due to the actuation authority. The second attached is another comparison plot showing the desired (full ss) and installed (discrete) filters. Finally the third attachment shows the installed susnorm filters which are forced to be flat at high frequencies.

[Copying the digital filter settings for ETMY]

This was done by running the existing code,

/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Scripts/CALCS/copySus2Cal.py

Darkhan, Kiwamu,

Taking a further look at the K values, we came to the conclusion that the discrepancies are due to rounding error of the N/A values written in H1params.conf. As described above, this will not cause appreciable effects at the precision level we usually talk about (~1 % level). We left them as they are.

Cheryl, Kiwamu,

Executing each line of NOISE_TUNINGS, we spotted typo in which MICH FF and SRCL FF1 were selecting a wrong set of digital filters. In particular, MICHFF was the worst -- it didn't use the AC coupling filter, resulting in a jolt to ITMs. We set them to the ones that had been used in the previous 30 hour lock stretch (31653). Cheryl will test this to see if the situation is better.

This one is labeled IBM AIP 192 (also LY-IBM)  - perhaps the 2K input MC tube?? Did we mislabel these?

The other red one is HAM12 on the 2K volume.

The one labeled IBM is on 2K volume, but there is no pump connected to annulus volume right now, which is why it's been red on vacuum GUI. That volume was pumped down and capped off at a valve. HAM 12 on vacuum GUI is actually HAM 11 (same with HAM7/8). We should fix wiring so they read right.

We were able to fix some obvious problems with this but the problem with the shield was not changed as we did not test it after the fact.  Though this problem should only appear if someone was in the rack.  
Would be interesting to see if anything is on 9,or 45MHz

I took at look at the auiliary channels we used to create DQ flags monitoring RF45 noise in O1, namely H1:LSC-MOD_RF45_AM_CTRL_OUT_DQ and H1:ASC-AS_B_RF36_I_YAW_OUT_DQ. I created BLRMS of these channels in the same way we did in O1 to threshold on. In all of these plots we see a steady BLRMS over 21 hours from 20th Nov 00:00 - 21:00 UTC, indicating that these channels do not see any form of RF45 noise we are used to:

* Plot 1 - BLRMS of H1:LSC-MOD_RF45_AM_CTRL_OUT_DQ between 10-100Hz in 60 seconds strides
* Plot 2 - BLRMS of H1:LSC-MOD_RF45_AM_CTRL_OUT_DQ between 10-100Hz in 1 second strides
* Plot 3 - BLRMS of H1:ASC-AS_B_RF36_I_YAW_OUT_DQ between 30-170Hz in 1 second strides

Hveto for this day indicated that H1:ASC-AS_A_RF45_Q_PIT_OUT_DQ was a good channel to veto noise with on Sunday. I therefore did a BLRMS of this channel:

* Plot 4 - BLRMS of H1:ASC-AS_A_RF45_Q_PIT_OUT_DQ between 5-100 Hz in 1 second strides

This channel does show excess noise at certain times of the day. If we were to threshold on this BLRMS using the 99.5% BLRMS value during this time period, we would capture the times Sheila mentions and also veto 8/10 top ten pycbc live triggers for this day. 

Not conclusive that this noise is RF45 noise similar to what we saw in O1, investigating further...

Seemingly another incident: circa 2016-11-23 20:25:30 Z.

I made an update to the quad matlab model to account for these mystery features. See CSWG log 11197.

I describe my use of the Frequency Domain System Identification toolbox (FDIDENT) to fit this transfer function in CSWG elog #11205. FDIDENT is a third party Matlab toolbox which provides tools for identifying linear dynamic single-input/single-output (SISO) systems from time response or frequency response measurements. The toolbox is free for non-profit use.

https://www.mathworks.com/products/connections/product_detail/product_35570.html

http://home.mit.bme.hu/~kollar/fdident/

A stable, but non-minimum phase, model without delay – compatible with a Linear Time Invariant (LTI) representation -- results in a best fit for a 22 order numerator and 28 order denominator model, m2228. The model is compared to the measurement data in the attached bode plot.

I attach several new parts of this high frequency characterization in order to facilitate incorporating the uncertainty in any future transfer function fitting. 

I attach three new text files:
    "..._tf.txt" -- a copy of the originally attached text file, columns are 
        [freq re(A) im(A)]
    "..._coh.txt" -- an export of the (prefiltered) coherence, columns are 
        [freq iEXCCoh PCALCoh]
    "..._relunc.txt" -- an export of the combined relative uncertainty on the transfer function, columns are 
        [freq sigma_A]

Computing the uncertainty on this actuation strength was a bit of a challenge. 
Remember, the above measure of the actuation strength of the UIM stage, A, is a combination of two transfer functions, as described in P1500248, Section V. In this aLOG they're referred to as "PCAL2DARM" where we use the photon calibrator as a reference actuator, and "iEXC2DARM" where the suspension stage under test is used as the actuator. Typically, the iEXC2DARM transfer function has the lowest coherence. 
Even worse, I've combined many data sets of both transfer functions covering different frequency regions each with a different number of averages.
Thus form the uncertainty, I've taken each frequency region's data set, and 
    - Filtered both iEXC and PCAL transfer functions for data points in which the iEXC TF has coherence greater than 0.95,
    - Created a relative uncertainty vector for each iEXC and PCAL transfer functions using the standard B&P equation,
        sigma_TF(f) / TF = sqrt( (1-C(f)) / (2 N C(f)) )
    where C(f) is the coherence, and N is the number of averages (N was 10 for swept sine TFs, 25 for broad band TFs)
    - Concatenated the data sets to form the overall transfer function, A,
    - Combined the two uncertainty vectors in the standard way,
        sigma_A / A = sqrt((sigma_iEXC / iEXC)^2 + (sigma_PCAL / PCAL)^2)
    - Sorted the collection of 
        [frequency complextf iexccoh pcalcoh sigma_A]
    by frequency.
    - Exported the uncertainty.

Note that one only needs one column of uncertainty, for the absolute uncertainty in magnitude is just
    |sigma_A| = abs(A) * (sigma_A / A)
and the absolute uncertainty in phase is
    /_ sigma  = 180/pi * (sigma_A / A)

I attach a plot of the magnitude and its uncertainty for demonstrative purposes, so that when the files are used, you can compare your plots of this against mine to be sure you're using the data right. Note that I've multiplied the uncertainty by a factor of 10 for plotting only so that it's visible.

I've updated and committed the function that's used to process this data, and it can be found here:
    /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER10/H1/Scripts/FullIFOActuatorTFs/
    process_H1SUSETMY_L1_HFDynamicsTest_20161117.m

The high-frequency dynamics measurements quoted in this aLOG have been analyzed. See results in LHO aLOG 31603.

J. Kissel, K. Izumi, D. Tuyenbayev,

Overview

Actuation strengths [N/ct] for all three stages have been calculated with MCMC method. In In this analysis we used data from last set of measurements taken on Nov 17 (see above), together with measurements from Nov 7, 8, 10 and 12 (see LHO alogs 31303, 31371, 31403, 31433). The calculated actuation coefficients are:

K_U = 8.1648^-8 N/ct

K_P = 6.844^-10 N/ct

K_T = 4.395^-12 N/ct

The H1DARM model parameters were updated using these values, particularty:

UIM_NpA = 1.739; [N/A]
PUM_NpA = 0.0334; [N/A]
TST_NpV2_y = 1.612e-10; [N/V^2]

We will double check the overall DARM loop model, with the updated sensing and actuation, by comparing it to DARM loop TF measurements.

Notice that TST actuation coef came out as a negative quantity, we believe that there is a "-1" missing in the model of this stage.

Details

For this analysis we took each actuation stage to DARM TF and PCALY to DARM TF measurements at the same frequency vector and used only data points with coherences above 0.9, we adopted a Matlab script used at LLO for this part of the analysis (see EvanG's LLO alog 29438). For each actuation stage i, the test point excitation to DARM TF is

iEXC2DARM = Ai,meas * C / (1 + G)

and PCALY to DARM is

PCALY2DARM = C / (1 + G)

The ratio of the two gives:

iEXC2DARM / PCALY2DARM = Ai,meas

Then we divided this my the model of the given stage without the N/ct coefficient, A_i,model / K_i,model = F_i,model, gives measurement of the frequency-independent N/ct coefficient:

A_i,meas / F_i,model = K_i,meas

Then, we used GWMCMC library (https://github.com/grinsted/gwmcmc) for fitting amplitude and phase of the N/ct coefficient for each stage (if the frequency dependent part of the model is correct, then the phase should be 0 deg). The log likelihood function used for fitting is

logLike = log( ∏( 1 / sqrt(2πσ_i²) exp( - (K_i,meas - K_fit)²/(2σ_i²) ) )

Fit results for magnitudes are given above and the phases are at the order of 10^-3 deg.

The K_U, K_P and K_T coefficients calculated from multiple-frequency transfer function measurements differ from earlier estimations from single line (LHO alog 31344) by 1.7%, 5.3% and 3.1% for UIM, PUM and TST stages. Possibly some unaccounted systematics in the frequency reponses of the DARM model near 35 Hz (the previous analysis was done with the DARM model for ER9).

Izumi K, Kissel J, Tuyenbayev D,

We used ER10 model to re-run an earlier actuation strength analysis using calibrartion line data from Nov 3 - Nov 8 (LHO alog 31344). The original analysis was done with the DARM model in which the positive N/ct sign was used for TST stage actuation, the correct K_T sign must have been negative. Below we list the updated results from this single-line analysis, the values are taken from GPS time interval [1162369920 1162413500]:

K_U = 8.613 × 10^-8 ± 3.204 × 10^-10 N/ct
K_P = 6.802 × 10^-10 ± 2.254 × 10^-12 N/ct
K_T = -4.341 × 10^-12 ± 1.339 × 10^-14 N/ct

Notice this analysis is used as an additional check of the multiple-frequency analysis (see above). The DARM model parameters for ER10/O2 will be based on the multiple-frequency analysis results (refined numbers and comparison results are coming soon).

Izumi K, Kissel J, Tuyenbayev D,

Overview

We calculated the actuation coefficients for the H1 DARM reference time model. For UIM (L1) and PUM (L2) stages the N/ct coefficients were fit based on actuation TF measurements on Nov 7, 8, 10, 12 and 15. These numbers have been reported earlier (see above). The TST actuation strength will have a trend over long time period due to charge accumulation, thus for TST stage it is better to estimate the coefficient based on measurements taken within a short period of time. Since we set the reference sensing function parameters based on measurements taken on Nov 12, for estimation of the TST (L3) stage actuation we decided to use measurements around that date, particularly measurements from Nov 10 and 12.

Contributions from each of the actuation stages to the overall DARM response drops as 1/f⁶, 1/f⁴ and 1/f², for this reason MCMC (and LSQ) fitting were restricted to [0 10] Hz, [0 200] Hz and [0, 200] Hz for UIM, PUM and TST stages respectively.

Below are the resulting N/ct values, these values:

K_U = 8.1648 × 10^-8 N/ct (±  0.074% 1-σ)
K_P = 6.844 × 10^-10 N/ct (± 0.018% 1-σ)
K_T = -4.389 × 10^-12 N/ct (± 0.031% 1-σ)

And the H1DARM model were updated in the following way (only the N/V2 for TST stage is different from LHO alog 31649):

UIM_NpA = 1.739;         % [N/A]
PUM_NpA = 0.0334;        % [N/A]
TST_NpV2_y = 1.6097e-10; % [N/V^2]

New EPICS values used for DARM time-dependent parameters have been calculated with the updated H1 DARM model for ER10/O2 (see attachment 1).

Comparisons

MCMC and LSQ methods gave consistent results, fractional discrepancies between the two were at the order of 10^-5 (LSQ fit was done only for magnitude).

Discrepancies between the new values and the ones currently installed in the CAL-CS front-end model are:

UIM: 0.05% (compared 8.1689 × 10-8 N/ct, the currently installed, old value)
PUM: 0.05% (compared to 6.8407 × 10-10 N/ct)
TST: 3.42% (compared to 4.239 × 10-12 N/ct)

Discrepancies between these values and an updated single-line analysis results (see LHO alog 31668 above) are 5.5% (UIM), 0.6% (PUM) and 1.4% (TST). A larger discrepancy between MCMC and the single-line analysis for UIM, we believe, is mostly due to 5-10% systematic errors in the UIM suspension model at ~36 Hz (see a residual plot attached to Kiwamu's LHO alog 31427).*

Although, the TST stage coefficient was calculated based on Nov 10th and 12th measurements, discrepancies between the values estimated for each of the 5 measurements (Nov 7 - 17), are within 0.5% (see attachment 2).

*Check out Jeff's LHO alog 31603 for more UIM HF investigations.

Details

TST stage fitting plots are attached below (see attachments 3 and 4). UIM and PUM fitting results did not change (see previous report above, LHO alog 31609).

The new EPICS values for DARM time-dependent parameters are committed to

${CalSVN}/Runs/ER10/H1/Scripts/CAL_EPICS/D20161120_H1_CAL_EPICS_VALUES.m

The up-to-date H1 DARM model parameters are commited to CalSVN:

${CalSVN}/Runs/ER10/Common/params/IFOindepParams.conf              r3752
${CalSVN}/Runs/ER10/H1/params/H1params.conf                        r3826
${CalSVN}/Runs/ER10/H1/params/2016-11-12/H1params_2016-11-12.conf  r3786

DARM model scripts (SRC detuning TF was modified to include Q-factor at r3814):

${CalSVN}/Runs/O2/DARMmodel/*  r3814

Actuation coefficient fitting script was uploaded to

${CalSVN}/Runs/ER10/H1/Scripts/FullIFOActuatorTFs/fitActCoefs_Npct.m  r3829

And the results are at

${CalSVN}/Runs/ER10/H1/Results/Actuation/2016-11-20_H1_SUSETMY_*.pdf

Summary

A refined analysis of the L1, L2 and L3 stange actuation strenghts was done using the data from last several days that include several low-noise lock stretches. Actuation strength factors are:

K_U = 8.020^-8 +/- 2.983^-10 N/ct   ( std(K_U) / |K_U| = 0.0037 )

K_P = 6.482^-10 +/- 2.748^-12 N/ct   ( std(K_P) / |K_P| = 0.0033 )

K_T = 4.260^-12 +/- 1.313^-14 N/ct   ( std(K_T) / |K_T| = 0.0031 )

Details

Following 4 lines were used to calculate the factors: UIM (L1) line at 33.7 Hz, PUM (L2) line at 34.7 Hz, TST (L3) line at 35.9 Hz and PcalY line at 36.7 Hz. The most recent DARM model parameters were used for this analysis. Also, values past Nov 5 were calculated with the updated DARM filters (see LHO alog 31201), not accounting for this would produce results biased by 1-2%.

Each data point is a quantity calculated from 10s FFTs. The outliers were removed in two steps:
- took the mean and the standard deviation of all data points in intervals when the IFO range was >=50 MPC, removed 3-sigma outliers;
- removed the 3-sigma outliers from the mean of the remaining data points.

The mean values and the standard devitaions noted above were taken from GPS time interval [1162369920 1162413500], ~11 hours of low-noise data (blue markers). Standard errors on the mean values, std(K_i) / sqrt(N), are orders of magnitude smaller compared to the Pcal and the DARM loop model uncertainties (number of data points in the seletected interval - N=4251).

For preliminary results from Nov 4 data and before see related reports: 31183, 31275.

Recall the ER8/O1 values for these coefficients were

    'Optic'      'Weighted Mean'    '1-sigma Uncertainty'    '1-sigma Uncertainty'
    'Stage'      '[N/ct]'           '[N/ct]'                 '%'                  
    'ETMY L1'    '8.17e-08'         '3.2e-09'                '3.9'                
    'ETMY L2'    '6.82e-10'         '5.2e-13'                '0.076'              
    'ETMY L3'    '4.24e-12'         '4.1e-15'                '0.096' 
from LHO aLOG 21280.

Comparing against numbers above,
    KU = 8.020-8 +/- 2.983-10 N/ct   ( std(KU) / |KU| = 0.0037 )
    KP = 6.482-10 +/- 2.748-12 N/ct   ( std(KP) / |KP| = 0.0033 )
    KT = 4.260-12 +/- 1.313-14 N/ct   ( std(KT) / |KT| = 0.0031 )

This means a change of
               (ER8 - ER10)/ER8 = 
    ETMY L1        0.0183
    ETMY L2        0.0495
    ETMY L3       -0.0047

We will compare these numbers against those determined by frequency-dependent transfer functions, e.g. the to-be processed data from LHO aLOG 31303, and update the low-latency/ calibration accordingly next week. It will also be interesting to re-cast the L1 and L2 numbers into a combined actuation strength change from ER10/O1, and compare it against the constantly calculated kappa_PU and check consistency there.

Data points prior to DARM filter update mentioned in the report were analyzed with the help of following DARM model parameters:

ifoIndepFilename : ${CalSVN}/Runs/PreER10/Common/params/IFOindepParams.conf (r3519)
ifoDepFilename   : ${CalSVN}/Runs/PreER10/H1/params/H1params.conf (r3640)
ifoMeasParams    : ${CalSVN}/Runs/PreER10/H1/params/H1params_2016-10-13.conf (r3519)

and after the the DARM filters were updated (GPS 1162336667) the following configuration was used:

ifoIndepFilename : ${CalSVN}/Runs/PreER10/Common/params/IFOindepParams.conf (r3519)
ifoDepFilename   : ${CalSVN}/Runs/PreER10/H1/params/H1params_since_1162336667.conf (r3640)
ifoMeasParams    : ${CalSVN}/Runs/PreER10/H1/params/H1params_2016-10-13.conf (r3519)

Scripts were uploaded to CalSVN at

${CalSVN}/Runs/PreER10/H1/Scripts/Actuation/2016-11-08/

5 days SLM data (75 MB): ${CalSVN}/Runs/PreER10/H1/Measurements/Actuation/2016-11-08/

Plots: ${CalSVN}/Runs/PreER10/H1/Results/Actuation/2016-11-08_H1_UPT_act_strengths_*

We discovered that in the single-line analysis we had an incorrect sign for TST stage actuation (we incorrectly set the sign of the N/ct coefficient).

The updated results have been posted in LHO alog 31668.