We have had multiple locklosses right near the end of the locking sequence around CLOSE BEAM DIVERTERS and OMC WHITENING. Today, we held at different states while locking. First, we pasued at MAX POWER while we waited for the R waves of a few different earthquakes to pass. Then, we proceeded successfully through to LASER NOISE SUPPRESSION. There are large glitches in this state, probably because of the CARM loop, so we stayed in the state to wait for the glitches to die down. Then, Corey selected ADS TO CAMERAS. This state proceeded fine, but we saw the 1 Hz starting to ring up. Corey selected the ASC Hi Gain script button on the seismic page to damp the 1 Hz back down. It damped down. We next went to INJECT SQUEEZING, which was fine. We waiting again about a minute after the state finished. Finally, Corey selected CLOSE BEAM DIVERTERS and we lost lock. Here is the guardian log so we can see the timestamps of each step.

We had the same lockloss earlier, it's logged at being from "omc whitening" but usually the beam diverters state is very fast so we are in omc whitening by the time the lockloss happens. Attached is the suspension signals from both locklosses. It looks like something rings up in DARM.

2025-11-05_00:36:48.787114Z ISC_LOCK [LASER_NOISE_SUPPRESSION.run] ezca: H1:IMC-REFL_SERVO_IN2GAIN => -29
2025-11-05_00:36:48.787719Z ISC_LOCK [LASER_NOISE_SUPPRESSION.run] ezca: H1:IMC-REFL_SERVO_FASTGAIN => -16
2025-11-05_00:37:24.445085Z ISC_LOCK REQUEST: ADS_TO_CAMERAS
2025-11-05_00:37:24.445085Z ISC_LOCK calculating path: LASER_NOISE_SUPPRESSION->ADS_TO_CAMERAS
2025-11-05_00:37:24.446434Z ISC_LOCK new target: ADS_TO_CAMERAS
2025-11-05_00:37:24.501243Z ISC_LOCK EDGE: LASER_NOISE_SUPPRESSION->ADS_TO_CAMERAS
2025-11-05_00:37:24.501532Z ISC_LOCK calculating path: ADS_TO_CAMERAS->ADS_TO_CAMERAS
2025-11-05_00:37:24.505287Z ISC_LOCK executing state: ADS_TO_CAMERAS (578)
2025-11-05_00:37:24.506308Z ISC_LOCK [ADS_TO_CAMERAS.enter]
2025-11-05_00:37:24.532550Z ISC_LOCK [ADS_TO_CAMERAS.main] ezca: H1:GRD-CAMERA_SERVO_REQUEST => CAMERA_SERVO_ON
2025-11-05_00:37:24.533290Z ISC_LOCK [ADS_TO_CAMERAS.main] camera servo guardian state
2025-11-05_00:37:24.533992Z ISC_LOCK [ADS_TO_CAMERAS.main] ezca: H1:ASC-AS_A_RF36_Q_YAW_SW1 => 8
2025-11-05_00:37:24.785056Z ISC_LOCK [ADS_TO_CAMERAS.main] ezca: H1:ASC-AS_A_RF36_Q_YAW => ON: OFFSET
2025-11-05_00:38:24.227696Z ISC_LOCK [ADS_TO_CAMERAS.run] ezca: H1:SUS-ETMX_L2_DRIVEALIGN_P2L_SPOT_GAIN => 3.13
2025-11-05_00:38:24.228345Z ISC_LOCK [ADS_TO_CAMERAS.run] ezca: H1:SUS-ETMY_L2_DRIVEALIGN_P2L_SPOT_GAIN => 4.89
2025-11-05_00:38:24.230162Z ISC_LOCK [ADS_TO_CAMERAS.run] ezca: H1:SUS-ETMX_L2_DRIVEALIGN_Y2L_SPOT_GAIN => 4.85
2025-11-05_00:38:24.230577Z ISC_LOCK [ADS_TO_CAMERAS.run] ezca: H1:SUS-ETMY_L2_DRIVEALIGN_Y2L_SPOT_GAIN => 0.78
2025-11-05_00:39:40.380293Z ISC_LOCK REQUEST: INJECT_SQUEEZING
2025-11-05_00:39:40.383415Z ISC_LOCK calculating path: ADS_TO_CAMERAS->INJECT_SQUEEZING
2025-11-05_00:39:40.386240Z ISC_LOCK new target: INJECT_SQUEEZING
2025-11-05_00:39:40.448133Z ISC_LOCK EDGE: ADS_TO_CAMERAS->INJECT_SQUEEZING
2025-11-05_00:39:40.448133Z ISC_LOCK calculating path: INJECT_SQUEEZING->INJECT_SQUEEZING
2025-11-05_00:39:40.453186Z ISC_LOCK executing state: INJECT_SQUEEZING (580)
2025-11-05_00:39:40.453467Z ISC_LOCK [INJECT_SQUEEZING.enter]
2025-11-05_00:39:40.471153Z ISC_LOCK [INJECT_SQUEEZING.main] ezca: H1:GRD-SQZ_MANAGER_REQUEST => FREQ_DEP_SQZ
2025-11-05_00:39:40.472228Z ISC_LOCK [INJECT_SQUEEZING.main] timer['CheckSqz'] = 90
2025-11-05_00:39:40.473316Z ISC_LOCK [INJECT_SQUEEZING.main] ezca: H1:GRD-SUS_PI_REQUEST => PI_DAMPING
2025-11-05_00:39:40.720211Z ISC_LOCK [INJECT_SQUEEZING.run] USERMSG 0: SQZ_MANAGER: has notification
2025-11-05_00:39:45.281174Z ISC_LOCK [INJECT_SQUEEZING.run] USERMSG 0: SQZ_MANAGER: has notification
2025-11-05_00:40:51.377382Z ISC_LOCK REQUEST: CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:51.378087Z ISC_LOCK calculating path: INJECT_SQUEEZING->CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:51.378087Z ISC_LOCK new target: CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:51.459548Z ISC_LOCK EDGE: INJECT_SQUEEZING->CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:51.459721Z ISC_LOCK calculating path: CLOSE_BEAM_DIVERTERS->CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:51.464167Z ISC_LOCK executing state: CLOSE_BEAM_DIVERTERS (590)
2025-11-05_00:40:51.465760Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.enter]
2025-11-05_00:40:51.475467Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] Closing REFL beam diverter
2025-11-05_00:40:51.476845Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] ezca: H1:SYS-MOTION_C_BDIV_A_CLOSE => 1
2025-11-05_00:40:51.476939Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] Closing AS beam diverter
2025-11-05_00:40:51.478119Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] ezca: H1:SYS-MOTION_C_BDIV_D_CLOSE => 1
2025-11-05_00:40:51.478494Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] ezca: H1:VID-CAM16_EXP_REQ => 36000
2025-11-05_00:40:51.579758Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] ezca: H1:VID-CAM16_EXP_SET => 1
2025-11-05_00:40:51.579758Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] Closing POP beam diverter
2025-11-05_00:40:51.580545Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.main] ezca: H1:SYS-MOTION_C_BDIV_B_CLOSE => 1
2025-11-05_00:40:53.156310Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.run] Unstalling IMC_LOCK
2025-11-05_00:40:53.347649Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.run] Unstalling VIOLIN_DAMPING
2025-11-05_00:40:53.521338Z ISC_LOCK JUMP target: LOCKLOSS
2025-11-05_00:40:53.521845Z ISC_LOCK [CLOSE_BEAM_DIVERTERS.exit]
2025-11-05_00:40:53.582367Z ISC_LOCK JUMP: CLOSE_BEAM_DIVERTERS->LOCKLOSS
2025-11-05_00:40:53.582367Z ISC_LOCK calculating path: LOCKLOSS->CLOSE_BEAM_DIVERTERS
2025-11-05_00:40:53.585523Z ISC_LOCK new target: DOWN
2025-11-05_00:40:53.590140Z ISC_LOCK executing state: LOCKLOSS (2)
 

Dr. Dripta B. and I went to EX today to do a PCAL End Station measurement with PS4 using the  T1500062 ES Power Sensor RR Meas : Procedures & Log.
I took a picture of the beam spots before we started, and after we were done. 
We ran Miriam's fantastic shell tool & left her some feed back written in the margins of the 2.2 section of the T1500062 Proc & Log document linked above.

We tried to run the measurement right at the end station but we didn't know that NDS servers were having a problem this week.
I eventually changed the server to be h1daqnds1 port 8088 to get the data instead.
       
Command Ran:
python generate_measurement_data.py --WS PS4 --date 2025-11-03
Reading in config file from python file in scripts
../../../Common/O4PSparams.yaml
PS4 rho, kappa, u_rel on 2025-11-03 corrected to ES temperature 299.5 K :
-4.7017855975867215 -0.0002694340454223 2.686163396659873e-05
Copying the scripts into tD directory...
Connected to h1daqnds1
martel run
reading data at start_time:  1446313243
reading data at start_time:  1446313659
reading data at start_time:  1446313992
reading data at start_time:  1446314497
reading data at start_time:  1446314910
reading data at start_time:  1446315256
reading data at start_time:  1446315430
reading data at start_time:  1446316080
reading data at start_time:  1446316490
Ratios: -0.46104301054554775 -0.4663040860974578
writing nds2 data to files
finishing writing
Background Values:
bg1 =        9.224674; Background of TX when WS is at TX
bg2 =        4.512480; Background of WS when WS is at TX
bg3 =        9.191238; Background of TX when WS is at RX
bg4 =        4.365167; Background of WS when WS is at RX
bg5 =        9.279967; Background of TX
bg6 =        0.429854; Background of RX

The uncertainty reported below are Relative Standard Deviation in percent 

Intermediate Ratios
RatioWS_TX_it      = -0.461043;
RatioWS_TX_ot      = -0.466304;
RatioWS_TX_ir      = -0.455583;
RatioWS_TX_or      = -0.461207;
RatioWS_TX_it_unc  = 0.084627;
RatioWS_TX_ot_unc  = 0.080522;
RatioWS_TX_ir_unc  = 0.093808;
RatioWS_TX_or_unc  = 0.083107;
Optical Efficiency
OE_Inner_beam                      = 0.988311;
OE_Outer_beam                      = 0.989318;
Weighted_Optical_Efficiency        = 0.988814;

OE_Inner_beam_unc                  = 0.058828;
OE_Outer_beam_unc                  = 0.054324;
Weighted_Optical_Efficiency_unc    = 0.080074;

Martel Voltage fit:
Gradient      = 1637.051728;
Intercept     = 0.515075;

 Power Imbalance = 0.988718;

Endstation Power sensors to WS ratios::
Ratio_WS_TX                        = -1.078345;
Ratio_WS_RX                        = -1.392858;

Ratio_WS_TX_unc                    = 0.050215;
Ratio_WS_RX_unc                    = 0.044908;

=============================================================
============= Values for Force Coefficients =================
=============================================================

Key Pcal Values :
GS           =      -5.135100; Gold Standard Value in (V/W)             
WS           =      -4.701786; Working Standard Value             

costheta     =      0.988362; Angle of incidence
c            =      299792458.000000; Speed of Light
             
End Station Values : 
TXWS         =        -1.078345; Tx to WS Rel responsivity (V/V)
sigma_TXWS   =        0.000541; Uncertainity of Tx to WS Rel responsivity (V/V)
RXWS         =        -1.392858; Rx to WS Rel responsivity (V/V)
sigma_RXWS   =        0.000626; Uncertainity of Rx to WS Rel responsivity (V/V)

e            =        0.988814; Optical Efficiency
sigma_e      =        0.000792; Uncertainity in Optical Efficiency

Martel Voltage fit : 
Martel_gradient         =        1637.051728; Martel to output channel (C/V)
Martel_intercept   =        0.515075; Intercept of fit of     Martel to output (C/V)

Power Loss Apportion : 
beta          =        0.998895; Ratio between input and output (Beta)  
E_T          =        0.993842; TX Optical efficiency 
sigma_E_T          =        0.000398; Uncertainity in TX Optical efficiency 
E_R          =        0.994941; RX Optical Efficiency 
sigma_E_R          =        0.000398; Uncertainity in RX Optical efficiency 

Force Coefficients : 
FC_TxPD          =        7.895132e-13; TxPD Force Coefficient 
FC_RxPD          =        6.181524e-13; RxPD Force Coefficient 
sigma_FC_TxPD          =        5.093350e-16; TxPD Force Coefficient 
sigma_FC_RxPD          =        3.738196e-16; RxPD Force Coefficient 
data written to ../../measurements/LHO_EndX/tD20251104/

This produced the following plots:

Martel_Voltage_test.png
WS_at_TX.png
WS_at_RX.png
WS_at_RX_BOTH_BEAMS.png

Running the the Following command makes the Trends plots for the ES measurement:
python pcalPublishReportsV5.py LHO_EndX tD20251104

LHO_EndX_PD_ReportV5.pdf  

All of this can be found at the PCAL git lab repo.  

TITLE: 11/05 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Preventive Maintenance
INCOMING OPERATOR: Corey
SHIFT SUMMARY: Maintenance Tuesday. Relocking hasn't been very successful so far. CO2Y was having IR faulting issues (alog87952), then we had a lock loss that occurred when we got to the Close_Beam_Diverters state, which we saw last week (alog87877). Now we are having a few earthquakes rolling through as we sit in max power. We don't want to advance until the ground stop shaking a bit so we can keep high gain asc on. 
LOG:                                                                                        

FAMIS 27570

pH of PSL chiller water was measured to be between 10.0 and 10.5 according to the color of the test strip.

TITLE: 11/05 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Preventive Maintenance
OUTGOING OPERATOR: TJ
CURRENT ENVIRONMENT:
    SEI_ENV state: EARTHQUAKE
    Wind: 10mph Gusts, 6mph 3min avg
    Primary useism: 0.52 μm/s
    Secondary useism: 0.35 μm/s 
QUICK SUMMARY:

Maintenance Day Recovery continues through the hand-off, but H1 locking is also being impacted by strong seismic activity (Russia EQs + microseism also inching back up).  Violins look elevated as well, so there has been attention given to them.

Hand-Offs from TJ:

• wifi is ON at EX, EY, MSR for Tony, so will need to turn OFF before OBSERVING
• CO2y laser tripped earlier today, and TJ hopes it will be fine, but just mentioned it.
• Currently taking H1 to LASER NOISE SUPPRESSION and Elenna wants to walk through the states to NLN slowly to watch for reasons for locklosses.

Ibrahim, Rahul

• Rahul tuned BRDs to previously found B/R modes of B = 19.55Hz and R = 31.67 Hz (alog 83461)
• On 10/12, measurements were taken that found mechanical modes to be at B = 19.72Hz and R = 31.85Hz (changes made to BBSS were wire coatings and the mass of BRD itself being simulated). Screenshots are attached.
• BRDs were installed, but there was a clearance issue that required a new part to extend the BRD out. This part was made and is currently in clean and bake. In the meantime, we used washers to extend the BRDs out using a mount hole. Pictures are attached.
• BRD measurements were then re-taken to see whether the Bounce and Roll modes were truly damped. It seems as though they were.
  • Note: We will likley require another round of retuning to the 10/12 values. As of now, the tuning is ~0.5% off for Roll and ~0.9% off for Bounce (and indeed, it seems Bounce is less damped than Roll).
• Rahul and I are planning to re-tune and re-install and re-measure with up-to-date mode measurements next week. 

In short, it appears that BRD damping is working.

M. Todd, S. Dwyer

We wanted to heat up OM2 and retake an OMC scan to get another measurement to compare against our models, as Sheila had the idea to use the SQZ beam which we know well at ZM5 and measure the overlap to the OMC. We were able to take some data at the very end of the maintanence period but we were having issues for a long time and gave up on having the OM2 hot for the measurement and let it cool down so that relocking could be on time today.

We did all the usual steps of turning the DC centering loops on for the OMs and put the OMC ASC on to center on the QPDs. In the future, here's what we should do.

Step 0 -- Turn on OM2 1hr45min before measurement

Go to IFO_OUT > OM2  and in the input box below "POWER_SET" in the bottom panel, set the power to 4.6. Wait 1hr45min.

Step 1 -- SQZ guardian to LOCKED_SEED_DITHER

Also make sure that there is no IFO power when you go to take your measurement.

Make sure the beam diverter is closed and that the seed launch power is around 75 (if not you may have to pico the half wave plate by going to SQZT0 and clicking on the lambda/2 near "Seed Launch"). Then take the SQZ manager to LOCKED_SEED_DITHER and make sure that OPO locks. You should also take the FC to misaligned, as this was causing flashes in our DCPDs we did not want and were confusing us.

Step 2 -- Open beam diverter and close DC centering

By opening the beam diverter and the fast shutter you should be able to get light on the AS_A and AS_B QPDs so that you can close the DC3 and DC3 centering loops. Then you can take the OMC guardian to OMC ASC and make sure the beam is centered on the OMC QPDs. The NSUM values we saw with the SQZ beam was around 0.001, so there isn't a ton of light on them.

--- You should be able to measure an OMC scan now  ---
If the HG10 peak is really high compared to the OM2 you may try closing the OMC LSC loop and waiting for things to settle before unlocking and remeasuring.

The OMC scans from today were not very good as the HG10 modes were much too high and don't make a good quadratic estimate of the mode-mismatch.

The IR sensor for CO2Y was intermittently going into fault. I resat the connector on the sat box and it seems to be okay now.

Today during maintenance the CO2Y laser tripped off 3 times. The first one we figured was due to cable pulling activity in the area, the second was a bit more of a mystery, and the third made us think there was definitely something wrong. Ryan C restarted the first two at the control box, needing to power cycle it at least once each time. The third time I went out there and noticed the IR fault light going on and off. I touched the cable that goes to the IR sensor itself and the lights on the IR satellite box went red. Simply placing my finger on the cable near the connector on the box was enough to bring it into fault. I checked the connector there and it had some play in it, so I tried to seat it a bit better and then it seemed to not be as sensitive to me touching it. I turned the key off and on again and it was good to go.

Because this last trip happened while we were powering up to 25W, there was about 20 minutes or so when CO2X was on at its nominal annular power, but CO2Y was off (~2107-2131UTC). Perhaps this is an interesting bit of time for someone to look at?

We ended up losing lock when powering up to 60W. Perhaps I should have waited longer after CO2Y was back to let it "catch up" to ITMX's thermal state.

Last week (87801) Jeff took a bunch of transfer function measurements for PRM for the PRM L, P, and Y estimators. There were some he wasn't able to take:

- H1ISIHAM2 to H1SUSPRM M1 for all dofs with DAMP L, P, and Y all with 20% gain

- H1ISIHAM2 to H1SUSPRM M1 for all dofs with DAMP Y at 20% gain

- H1SUSPRM M1 to M1 for V, R, P, Y with DAMP Y at 20% gain

Today I was able to get the first two bullet points done

Measurements:

First, I made sure the SUSPOINT matrix had the correct values for driving PRM, which it did. 

First set (L P Y DAMP gain at 20%):

L, P and Y DAMP gains were set to 20% of their nominal values, so they were set to -0.1, and T, V, and R were left at their nominal -0.5 gain values. 

Measurements can be found in 

/ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/PRM/Common/Data/2025-11-04_1800_H1ISIHAM2_ST1_PRMSusPoint_M1LPYDampingGain0p1_WhiteNoise_*_0p02to50Hz.xml r12766

Second set (Y DAMP gain at 20%):

After those measurements were taken, I set the L and P DAMP gains back to their nominal values of -0.5 and took another set of SUSPOINT measurements with only the Y gain at 20%.

Those measurements can be found in 

/ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/PRM/Common/Data/2025-11-04_1930_H1ISIHAM2_ST1_PRMSusPoint_M1YawDampingGain0p1_WhiteNoise_*_0p02to50Hz.xml r12767

I ran out of time and wasn't able to finish the four M1 to M1 dofs that were left for the reduced Y damping, so we'll have to get those next week.

I also wasn't able to get in any measurements for SRM, but that's okay since we're not in a rush.

The LVEA has been swept, I unplugged an extension cords that were not connected to anything, and the genie lift near the west bay.

The test system for 4k Ethernet was moved from EY to EX, ending the test at EY.  

The link was tested between the MSR and EX at 100G for a short itme.  The link tested at 80G, the maximum the software can test.

The link is now being tested long-term at 25G.  So far, no issues.

Earlier log entry about test at EY https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=87811

I inspected the PSL chiller lines external to the PSL enclosure this morning and found no issues or anomalies.  This closes FAMIS 27545.

[Jenne, TJ, Elenna]

The last three locks saw a violin mode ring up (see 87933), which managed to saturate the DCPDs and cause a large amount of excess noise, see this screenshot of DARM near the time of lockloss. I am assuming that all of the extra noise is a result of some crazy nonlinearity due to the saturation DCPDs.

Jenne and I have concluded that the mode that rung up must be ETMX mode 1, which the violin mode monitor screen reports is at f = 511.2993 Hz. However, we have looked at GDS calib strain when the mode has rung up using both diaggui_test and with exported data in python at double precision with fft length of 4096 and 1024 seconds respectively and find that the mode is at 511.269 Hz, DTT screenshot, matplotlib screenshot.

Jenne has plotted both the damping filter and the monitor filters here. We can see that the damping filter is broad enough to cover this frequency, but the monitor filter is not. The violin mode guardian is supposed to track the modes via the monitor filters and disengage damping if the mode is ringing up. However, we think the monitor filter might be missing this frequency and this is why the damping did not turn off.

The attached timeseries also shows that the DCPDs were railed for some time, the suspension drive on ETMX L2 was very nearly saturated, and the monitor filter level was low overall, near 3.5. Jenne has included channel H1:FEC-88_ACCUM_OVERFLOW, maybe this is a useful channel for us to monitor.

I just want to add that I am being specific about how we measured the mode frequency above because we have been confused by insufficient precision before. I think we have sufficient precision to measure this frequency accurately, but the results show a shift of 0.02 Hz from the previously reported value.

I had to do this check a week ago, but no damage was observed at either end.

Closes FAMIS 27396. Last checked in alog 87787

Plots look fine compared to last week but BSC High-Freq noise is elevated for these sensors:

ITMX_ST1_CPSINF_H1
ITMX_ST1_CPSINF_V1
ITMX_ST2_CPSINF_V1   

Note - it is Tues Maint. so there are people in the LVEA.

There was a 7.5Hz peak in TJ's last-week check that is now gone. It was most prominent in HAM1 it seems.

Pdf Attached.

TITLE: 11/04 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Aligning
INCOMING OPERATOR: Oli
SHIFT SUMMARY: One lockloss, we are relocking at MAX_POWER.
LOG:                                                                                                                                                                                                                                                                                                                                                            

03:45 UTC Something started to ring up in the DCPDs and the 500Hz line looked large on DARM. None of the vioins were ringing up though, I eventually found that both ETMY and ETMX (mostly ETMX) mode1/6's drive was ringing up and once I turned off the damping the DCPDs came back down and so did the line on DARM. (tagging SUS). I then put the nominal gain back into ETMX mode6 and it started to damp back down.

04:03 UTC We dropped observing, I brought us to Hi gain ASC as a semi large earthquake from Eastern Russia was hitting us (6.0)

04:19 UTC lockloss from the Earthquake

04:55 UTC MC2 M3 tripped as the IMC was trying to relock after a lockloss from FIND_IR, a look at some of the OSEMs

04:56 UTC IA, after INPUT_ALIGN it took the IMC 6 minutes to relock itself

J. Kissel

Gathered H1SUSPRM M3, M2, and M1 Drive to M1 Response TFs to inform the "drive" models for a future H1SUSPRM estimator. I'll post the locations / file names in the comments. Here in the main entry, I discuss the state of the control system for H1 SUS PRM so we understand with how much salt would should take these measurements.

Executive summary :: there are some side quests we can launch -- especially on the actuation side of this suspension -- if we think that these measurements reveal "way too much cross coupling for an estimator to work." The first things I'd attack would be 
    - the frequency-dependent and scalar gain differences *between* the nominal low noise state of the coil drivers and the state we need to characterize the suspension. 
    - the very old coil balancing, which was done *without* first compensating for any frequency-dependent gain differences in the channels at the frequency used to balance the coils (see LHO:9453 for measurement technique.)

Here's the detailed summary of all the relevant things for these measurements:
    - The suspension was ALIGNED, with alignment offsets ON, with slider values (P,Y) = (-1629.783, -59.868) ["urad"] 
        :: ALIGNED is needed (rather than just DAMPED [where the alignment sliders are OFF] or MISALIGNED where extra large alignment offsets are ON; per discussion of how the alignment impacts the calibration in LHO:87102)
        :: the usual caveats about the slider calibration, which is still using the [DAC ct / "urad"] gains from LHO:4563).

    - The M1 damping loop were converted to Level 2.0 loop shaping in Jan 2023; LHO:66859, nominally designed to have an EPICs gain of -1.0. However in Aug 2023, the EPICs gains were lowered to -0.5, and have been that way for most of O4, and remain that way now. For all of these measurements, I set the L, P and Y gains to -0.1; the "20% of nominal" gain mantra we've used for the HLTS estimators. I also gathered *almost* all the measurements again with only the Y gain at -0.1, but ran out of time to complete that set for comparison. 

    - Even though it was maintenance day, when we typically turn site-wide sensor correction OFF, I manually turned ON sensor correction for ISI HAM2 to get better coherence below 1 Hz (using instructions in LHO:87790)

    - The M3 L to M3 P filter (and gain) in the M3 DRIVEALIGN frequency-dependent matrix is OFF, per LHO:87523. 

    - There are (M3 P to M3 L) = 1.7 and (M3 Y to M3 L) = 0.52 scalar gains ON in to off-diagonal elements of the M3 DRIVEALIGN matrix whose purpose is change the center of P and Y actuation to be around where the IFO's beam spot typically is.

    - There is a set of M1 L to M1 P filters, "M1L_M3P" and "invM1P_M3P," in the M1 DRIVEALIGN matrix, with a EPICs gain of -1. I think these came from LHO:42549. The measurements I took aren't impacted by this, as I drove from the M1 TEST bank which does not send excitation through the DRIVEALIGN Matrix. HOWEVER, we'll definitely need to consider this when we model the ISC drive which *does* go through the M1 DRIVEALIGN matrix.

    - All M1, M2, and M3 stages of OSEM PDs sat amp whitening filters have been upgraded with ECR E2400330's filter design, and compensated accordingly. 
        :: M1 stage LHO:85463
        :: M2 & M3 stages LHO:87103

    - All M1, M2, and M3 stages of OSEM PDs have been calibrated via the ISI GS13s, and calibrated in the ALIGNED state (LHO:87231)

    - In order to get decent coherence over the band of interest for the M3, M2, and M1 drives, I had to drive the suspension actuators in their highest range state, which is different from the state the IFO usually needs.
        :: M1 = State 1 "LP OFF" (a Triple TOP Driver)
        :: M2 = State 2 "Acq ON, LP OFF" (An ECR E1400369 Triple Acquisition Driver "TACQ" modified for an extra 10x actuation strength. Modified in Sep 2013 LHO:7630)
        :: M3 = State 2 "Acq ON, LP OFF" (An ECR E1400369 Triple Acquisition Driver "TACQ" modified for an extra 10x actuation strength. Modified in Sep 2014 LHO:13956)

        :: The nominal state for the switches are M1 = State 2 "LP ON," M2 = M3 = State 3 "ACQ OFF, LP ON."

    - No actuator channels have had any precise compensation for their coil driver's frequency response in any state.
        :: M1 state 1 channels are all compensated with (z:p) = (0.9 : 30.9996) Hz
        :: M2 state 2 channels are all compensated with (z:p) = (64.9966 : 13) Hz
        :: M3 state 2 channels are all compensated with (z:p) = (64.9966 : 13) Hz

    - There are scalar "coil balancing" non-unity magnitude gains on each of the M2 and M3 stage channels, but it's the same values that have been in play since Jan 2014 (LHO:9419; so, after the M2 TACQ driver mod, but before the M3 TACQ driver mod). There is no coil balancing gains on the M1 stage, they're all either +/- 1.0.