L. Dartez, E. Goetz, J. Kissel, T. Shaffer

After we killed the lock stretch by turning on the extra 16 kHz anti-aliasing filter (LHO:82412) -- we found that the OMC wouldn't lock after 4 to 5 attempts during the next lock acquisition attempt. We turned on the 16 kHz AA filter early in the lock acquisition sequence "it would just work" and really -- thinking the cause of the lock loss was the loss of phase margin in the DARM loop. 

However after seeing the abnormally large number of failed OMC attempts, we suspected the new filter again. 
Then we realized -- the extra AA filter will cause phase loss at the 4.19 kHz OMC LSC dither line, and thus the OMC LSC DEMOD needs to be rephased to account for it.

The magnitude / phase of the 65k to 16kHz AA filter at the 4.19e3 Hz dither line frequency is 1.0837 [ct/ct] / -77.2 [deg].

As such, we adjusted the H1:OMC-LSC_PHASEROT from 56 deg to 56 [deg] - 77 [deg] = -21 [deg], and the OMC "locked right up."
(We assume that an 8% increase in the OMC LSC dither line signal would only be *good* for the OMC locking, but this will be confirmed with others later.)

We are now in Nominal Low Noise with the extra AA filter on, and have been for 8 minutes (and the many minutes prior that it takes to get from transitioning to DC READOUT and getting to Nominal Low Noise).

I've accepted the two changes in the safe and OBSERVE SDFs for the h1omc and h1iopomc0 front-end models.

Thu Jan 23 10:11:46 2025 INFO: Fill completed in 11min 43secs

Gerardo confirmed a good fill curbside. TCmins [-79C,-77C] OAT (0C,32F). delta-temp trip 10:11:53

J. Kissel, E. Goetz, L. Dartez

The lock loss at 2025-01-23 16:41:17 UTC (08:41 PDT Thursday morning) was a a result of our first attempt to turn ON the additional 65k to 16k digital AA filter (see LHO:82404 and references therein). 

Out of the utmost precaution we (via command line) performed what we do all the time (via script) for a analog whitening filter change: 
     - via command line, ramped all DARM error signal over to DCPDB by simultaneously changing the gain the 16 kHz filter banks (H1:OMC-DCPD_A_GAIN and H1:OMC-DCPD_B_GAIN) from A:1.0 and B:1.0 to A:0.0 and B:2.0 with a ramp time of 10 seconds. 
     - switched ON the second copy of the 65k to 16k "Dec16k" filter in FM10 in the 524 kHz filter bank for A, H1:OMC-DCPD_A0
     - command line ramped all DARM error over to DCPDA, from A:0.0 and B:2.0 to A:2.0 and B:1.0 with a ramp time of 10 seconds...
... and it was most of the way through that 10 second ramp back to the new filter configuration of DCPDA that we lost lock.

We're going to try again, but this time have the new AA filter configuration on already during lock acquisition.

TITLE: 01/23 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 156Mpc
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 12mph Gusts, 10mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.19 μm/s
QUICK SUMMARY: Locked for almost 3 hours, two auto relocks over night. No alarms this morning. Planned commissioning and calibration this morning from 1630-2000UTC.

TITLE: 01/23 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 155Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY:
H1 has been locked and Observing for just under 8 hours.
It's been a quiet night.
No locklosses, but No events either though.

Famis 28389

Looking for the latest In-Lock Sus Charge files i find that last ones were made on Jan 7th and already alogged 82163 .

cdsws25: ls /opt/rtcds/userapps/release/sus/common/scripts/quad/InLockChargeMeasurements/rec_LHO  -lt | head -n 6
total 527
-rw-r--r-- 1 test_user          controls   160 Jan  7 07:58 ETMX_12_Hz_1420300733.txt
-rw-r--r-- 1 test_user          controls   160 Jan  7 07:50 ETMY_12_Hz_1420300262.txt
-rw-r--r-- 1 test_user          controls   160 Jan  7 07:50 ITMY_15_Hz_1420300244.txt
-rw-r--r-- 1 test_user          controls   160 Jan  7 07:50 ITMX_13_Hz_1420300243.txt
-rw-r--r-- 1 test_user          controls   160 Dec 17 07:58 ETMX_12_Hz_1418486333.txt

Since I thought I remember us being locked this past Tuesday morning I checked to see if the SUS_Charge Guardian ran  and it looks like it didn't run, but we were actually locked?

TITLE: 01/23 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
INCOMING OPERATOR: Tony
SHIFT SUMMARY: Planned commissioning time today that focused on a PR2 spot move. There was a lock loss during this spot move and we decided to revert the move. Recovery was a bit challenging, but pico hysteresis or similar could be the cause. Read more below. One side effect of the picoing from the PR2 move, is that the ALS camera spots are slightly different. Some of the clipping that we would see on ALSY is no longer there and ALSX now has some in the top left corner.

• 1824 Lock loss during PR2 spot moving
  • Recovery
    • It was decided to revert all the moves that were made during the PR2 moves. I chose a point in time just before the commissioning period started and then used the restore all script. I initially forgot that this script, purposefully, doesn't change PR3 and so I had to by hand move PR3's sliders back. Archaic.  From there Jenne D suggested that we try to lock ALS and we may have to move the A-8 pico.
    • I wasn't able to get ALSX flashes above 0.1, but Y was up near 0.6 max. Jenne increased the gain for Y and then quickly moved the pico back in the direction that was moved during the PR2 movement, this brought up both arm powers and ALSY was able to stayed locked. A few iterations of this with more aligning between and then green initial alignment was complete.
    • The rest of initial alignment and main locking was automatic.
• 2053 Lock loss at low noise
  • We were in NLN for 2 min then a large ETMX glitch seemed to kill the lock (alog82406). Robert was out in the LVEA at the time, but doing things he has done before.
• 2215 Observing
  • Fully auto relock.
• 2256-2258 Out of observing for Xtreme PI damping

LOG:

TITLE: 01/23 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 155Mpc
OUTGOING OPERATOR: TJ
CURRENT ENVIRONMENT:
    SEI_ENV state: SEISMON_ALERT
    Wind: 2mph Gusts, 1mph 3min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.20 μm/s
QUICK SUMMARY:
All systems seem to be working well. (Execpt that Dust monitor)
Just transitioned into Earthquake mode for a 5.8 M earthquake, hopefully we can ride it out.

Sheila, Jenn{e,ie}, Robert

Continuing efforts to find out how to minimise the beam from PR2 clipping on the scraper baffle, as investigated in alogs #[77870, 77968, 77988, 81329].

At the start Sheila and Jenne agreed we should try to find the two extrema where the beam going from PR2 to PR3 clips the scraper baffle and the one going from PRM to PR2 clips the scraper baffle.

Sheila measured the PR2 Y2L gain by minimising the transfer function from PR2 yaw position to PRCL_OUT, while injecting a line at 30Hz as in [LHO alog #82251] entry.

New P2L: -0.36 from the measurement I did the other week.

New Y2L: -6.25 

Now the aim was to move the spot on PR2 to find where each beam hitting it clips the PR2 scraper baffle.

Move PR3 in negative yaw while monitoring LSC-POP_A_LP_NORM (pop power) and PR2 inmon on M1 to check ASC is not changing much to ensure we do not unlock the IFO. Every 13 PR3 microradians is 0.5mm.

We stepped 96 uradians to 68 microradians on PR3 yaw and corrected pitch down every time we dipped too low on LSC-POP or PWR_CIRC, every 1 microradian or so jenne moved picomotor A_8 (the one that aligns to both the ALS PDs and the LSC-POP PDs) by -50 counts to bring back the LSC POP alignment.

I measured our new Y2L to be -5.75 gain at this new value (moved 1 mm according to Jenne's script). Robert looked at the beam reflected off the baffle to the viewport at this point as a check of the power in it relative to our nominal position for the PR2 beam spot.

We kept going after this point but lost lock after moving about 8.5 microradians.

1421614404

ETMX glitch, and it looks like it was glitching for a tens of seconds before we lost lock - shot from lock lost tool.

Interestingly, ALSX was having issues staying locked after this lock loss. See attached for an example.

L. Dartez, E. Goetz, J. Kissel

Yesterday's test results and plots show that 
(a) Installing one additional copy of the existing 65 kHz to 16 kHz "Dec16k" filter improves the 20-2000 Hz band aliasing dramatically, where as that *and* one additional copy of the 524 kHz to 65 kHz "Dec65k" filter does not significantly improve the 20-2000 Hz band aliasing (but one copy is still required). See LHO:82405
(b) We have (just barely) enough phase margin in the DARM loop to install more digital anti-aliasing. (I plan to make better plots today, but see page 1 of 4th attachment of LHO:82387)
(c) We have (just barely) enough CPU clock-cycle turn-around time to install a few more filters (see 2nd attachment of LHO:82375). If this proves problematic, we can start clearing out test filters to claw back computation time.

As such, we plan to move forward with installing an additional 65k to 16 kHz "Dec16k" filter in the primary GW-channel, 524 kHz, DCPD A0 and B0 banks tomorrow.

We happen to be unlocked now, so I've staged (loaded in, installed, but NOT turned off) the new additional filter in the A0 and B0 bank into the H1IOPOMC0.txt foton file.

While there, I took the time to improve the name and clarity of the A0 and B0 filter banks, much like I've done in the A1, A2, B1, B2 test banks (in LHO:82313),
    - Renamed "NewV2A" and "NewAW" in the A0 and B0 banks -- which are *different* filters, to compensate for the *different* analog electronics in those PDA and PDB chains -- to 
         . "PDA_V2A" and "PDA_AW" 
         . "PDB_V2A" and "PDB_AW" 
    - Split out the gain that was in "cts2V" = gain(0.0006105)*gain(0.25)*gain(0.25) into two banks "18b_cts2V" and "sum4avg"
         . For the "18b_cts2V" gain, even though gain(0.0006105)*gain(0.25) = gain(0.000152625) which DOES NOT equal the "right" gain of 40/2^18 = 0.000152587890625, (a ratio of 1.0002432, or 0.24% different). In the spirit of moving stuff around without changing anything I installed the a gain(0.000152625) for now. Also, at the 0.24% level, the channel to channel gain is probably different anyways, and comes out to some make-shift value anyways in the 4-channel averaging. The "not right" gain comes from the typo of 40/2^16 = 0.0006103515625, which was installed as 0.0006105.
         . The "sum4avg" is the gain(0.25) you would expect to turn the sum of 4 channels into an average.
    - Moved the "18b_cts2V" , "sum4avg" and "A2mA" gains to be in FM3, FM4, and FM5
    - Such that now there's a "Dec65k" in FM8, and two copies of "Dec16k" in FM9 and FM10.

Also -- since the H1:OMC-PI_DOWNCONV_INMTRX matrix is configured to use only DCPD A, I made similar changes OMC PI DOWNCONV SIG bank, except -- in tthe event we ever need to switch the sig bank over to DCPD B, I installed the "PDB_V2A" and "PDB_AW" filters there as well.

See attached screenshots.
    (1st) Screenshot of the A0 and B0 banks *before* any changes were made

    (2nd) Screenshot of the A0 and B0 banks *after* the changes described above were made. NOTE that FM10 is turned OFF.

    (3rd) Screenshot of the OMC PI DOWNCONV SIG bank *after* the changes.

    (4th) Screenshot of SDF accept of new arrangement of A0 and B0 filters.
    
    (5th) Screenshot of SDF accept of new arrangement of OMC PI DOWNCONV SIG filters.

The updated filter file is commited to
    /opt/rtcds/userapps/release/cds/h1/filterfiles/H1IOPOMC0.txt        rev 30480

The updated safe.snap (which is linked to both the safe.snap and OBSERVE.snap) has been committed to
    /opt/rtcds/userapps/release/cds/h1/burtfiles/h1iopomc0/safe.snap       rev 30481

As noted in LHO aLOG 82394, I recommend starting improvements by adding an additional 16k downsampling filter. Attached is a figure showing a comparison of the current situation (red), just 2 16k filters (green), 2 16k filters and 1 65k filter (magenta), and 2 16k filters and 2 65k filters (black). The curve colors are the same as the original FOTON plots in LHO aLOG 82375. These curves are ratios of PSDs using different downsampling filters on the time series data that is manually downsampled by a factor of 32 (524k ==> 16k) versus PSD of the original 524k data (cut off with the maximum frequency of 8192 Hz).

The narrow instrumental artifacts are visible by eye in the 8 s FFTs of the DTT measurements, and are much more visible in the CW analyses that use longer coherence times. We can quantitatively assess the improvement by comparing the number of bins in this short analysis that are 1% in excess of the nominal ratio of 1:

Full band:
16k 65k bins above 1% = 14847
16k 16k bins above 1% = 6686
16k 16k 65k bins above 1% = 4892
16k 16k 65k 65k bins above 1% = 4809

0 - 2 kHz band:
16k 65k bins above 1% = 430
16k 16k bins above 1% = 21
16k 16k 65k bins above 1% = 0
16k 16k 65k 65k bins above 1% = 0

Note that even though the 2 kHz band has only a few hundred bins above 1%, these artifacts are strongly visible in run-averaged spectra that use longer coherent baselines, similar to all-sky CW searches.

One can see that the additional 16k filter does most of the clean up (we don't see a significant change by an extra 65k filter). By employing an additional filter, this should hopefully reduce or eliminate the impact of the narrow instrumental artifacts.

Wed Jan 22 10:03:51 2025 INFO: Fill completed in 3min 48secs

Gerardo confirmed a good fill curbside. TCmins [-78C, -60C] OAT (-1C, 30F)

TITLE: 01/22 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 3mph Gusts, 2mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.25 μm/s
QUICK SUMMARY: Locked for 12 hours, useism dropped quickly overnight. Planned commissioning time this morning.

TITLE: 01/22 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY:
One lockloss and a successful return to Observing at 3:43 UTC.
Otherwise a quiet night.

LOG:
No Log

TITLE: 01/22 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Lock Acquisition
CURRENT ENVIRONMENT:
    SEI_ENV state: USEISM
    Wind: 4mph Gusts, 3mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.64 μm/s
QUICK SUMMARY:

Unknown Lockloss from NLN.

 

The h1cam23 camera process got stuck.  I looked at it with Tony.  We shutdown and restarted the corresponding network switch port to power cycle the camera.  Then restarted the server process via monit.  That didn't work.  I ended up having to go onto h1digivideo2 and manually issue the kill command and send a SIGKILL to the camera process.  After that the camera process started up nicely and gave us a feed.

J. Freed

Before the hoidays as shown in 81658, the Double Mixer had large phase noises at 4096Hz that were thought to be caused by phase offest difference in the Double Mixer. Thanks to Marc Pirello for the suggestion and help to manually adjust the phase difference by extending the wire lengths inside the double mixer. 

DM_PN2.pdf Shows the lower 4096Hz peak in the path adjust(green) as compared to the no path adjust (blue) and both compared to an independant SRS (orange). The harmonics are still large so  DAC output had a ~5kHz low pass applied but with negledgable improvement. Investigation was ongoing when I went on holiday. 

Today I plugged in the double mixer into a network analyzer to see the power spectrum density of the signal 

DM_NA_WIDE.pdf Shows that although the DM has better noise floor, the harmonics of the double mixer are quite a bit worse in the Power spectral desnity than shown in phase noise DM_PN2. The best result (shown) was with NO added length. Unsure why this is. 

DM_NA_NARROW.pdf Besides that the signal has a fairly pure tone, though this is limmited by the resolution.

Investigations ongoing 

Following up on log  82252,  I made movies of HAM3 from the PR2 camera viewport last Thursday as I moved CPy over its pitch range and then, at nearly maximum pitch up, I ran it over its yaw range. In the movie (https://youtu.be/0f0F7cWqpwQ ), the beam spot appears to stay on the ballast baffle. At this highest pitch there appears to be a second spot on the support structure of the baffle. This second spot would be a little lower at the nominal setting. A steeply angled baffle that stuck down a little below the edge of the table might mitigate both of these stray beams.