IFO locked for past 5 hours. The ring down of the violin modes continues. There was a smallish EQ around 08:00 (01:00PT) which did not appear to reexcite the violin modes. Range has been slowly improving and is up around 52Mpc. No issues to report.   

TITLE: 07/08 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Earthquake
INCOMING OPERATOR: Jeff
SHIFT SUMMARY:  Locked for most of the shift.  Worked on damping violin modes, but didn't make much headway.  We have been around 50 MPc tonight.  Ran IA after the one lockloss, but it didn't improve anything.
LOG:  None

Due to me attempting to damp violin modes.

Have been attempting to damp many violin modes, but have had success on only a couple.  The largest ones that are giving us the most trouble seem to be unresponsive.

One sensor on the BS looks a little elevated, but hasn't reached the notification threshold. Otherwise all cps look fine.

TITLE: 07/07 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Earthquake
OUTGOING OPERATOR: Jim
CURRENT ENVIRONMENT:
    Wind: 18mph Gusts, 15mph 5min avg
    Primary useism: 0.05 μm/s
    Secondary useism: 0.05 μm/s
QUICK SUMMARY:  The battle with violin modes continues.  They shall be conquered.

TITLE: 07/07 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Earthquake
INCOMING OPERATOR: Travis
SHIFT SUMMARY: VIOLINS
LOG:
Spent the whole day damping violin modes. Locking has been relatively easy, but whack-a-mole is getting tedious.

For the most part, all look to have been operating within acceptable parameters until thje Montana EQ trouble between the 5th and the 6th. Curious that ETMY PIT seems to have been on a downward trend for the past week, however.

Trends reflect the change in operating current of the pump light. Weird chiller pressures about 5 days ago are a bit strange but don't seem to be of any consequence. Everything else looks normal.

   Locked at NLN for about 5 hours. Violin modes continue ringing down. DARM noise remains elevated and range is holding around 35Mpc. Turning over to the day shift. 

   Relocked at NLN. ETMX violin modes are still rung up, but slowly coming down. The DARM spectrum is elevated above 80Hz and slowly improving. A2Ls are both below the reference. Damped PI Modes 26 and 27 by a Phase sign flip. Continuing to limp along. Working on damping as limited capabilities allow. 

NOTE: Due to apparent profile problems on laptop cannot open either Firefox or Thunderbird. This is limiting capabilities somewhat.   

J. Kissel, J. Bartlett

For funzies, on my way out, I taught Jeff how to turn on and off DCPD whitening so I could check whether we had done enough damping today to get us back into the nominal configuration of 1 stage of DCPD whitening. 
Nope. 
We heard verbal indicate that we were saturating the DCPDs with one stage of whitening. 
We lost lock while trying to remove the stage of whitening we added in.

So -- back at it tomorrow!

J. Kissel, C. Vorvick

We spent the remainder of the shift trying to damp violin modes as best we could with the IFO in DC readout, but with no stages of DCPD whitening. We were able to reduce the RMS counts of ADC input on the DCPDs by about a factor of 5, by performing all the already known violin mode damping tricks for the fundamentals (~500 Hz) and 2nd harmonics (1000 Hz), as per Nutsinee's glorious work on the sacred LHO violin mode table. However, this earthquake has rung up *every* harmonic.

So, I begun the task of developing filters to damp the previously-undamped 3rd harmonics. I took a few hours of play, but I was able to known down the 6 highest RMS contributors, but there's still plenty more to go. I've added new rows to the violin mode table that detail the configuration and filters I created, but I summarize here:

EX      1478.17      MODE 1     FM 4 6 7, G = -1000
EX      1475.25      MODE 2     FM 4 6, G = -1000
EX      1474.08      MODE 3     FM 4 6 8, G = -2000
EX      1471.93      MODE 5     FM 4 6 7, G = -2000
EY      1484.53      MODE 2     FM 4 6 8, G = +2000
IX      1467.96      MODE 1     FM 4 6 7, G = -2000

These details may change over time as we consolidate filter banks, so always treat the violin mode table as cannon, not this aLOG.
Note that all of these settings are for a 30W, DC readout IFO, with PUM coil drivers set to State 3, and driving in Pitch.

The filter design process at 1.5k has become pretty straight-forward:
- Have a "live" (3 avgs, exponential) DTT spectra of H1:OMC-DCPD_A_IN1 and H1:OMC-DCPD_B_IN1 going with RMSs of each and a reference plotted for all (like I have attached). 0.005 Hz BW, so you can nail down which mode you're attacking. (Pick the one that's contributing the most to the RMS in the 1.5 kHz band). 
- Also have a live DTT spectra of H1:DARM_IN1_DQ going, at faster pace (I chose 0.02 Hz BW) for use while tuning the gain and phase.
- Copy the 1.5k set to a new empty filter bank (thanks for that now-essential feature Jim Batch!)
- Adjust the frequency of the bandpass to be centered around the mode you're trying to attack. I've been successful with ~0.3-0.5 Hz bandwidths. Note, once I have a bandwidth I like (where my figure of merit is "how fast is the phase wrapping?" I shoot for less that 3-4 phase wraps in the bandpass frequencies), I shift the bandpass up or down such that the phase at the exact frequency of the mode is 0 +/- 5-10 [deg].
- Adjust the "-60 deg" filter by highlighting the zpk portion, hitting the ZPK button, switching to Mag/Phase, then adjusting the frequency of the complex pole (i.e. add new, and remove old) by 10-50 Hz until I get -60+/-5 [deg] at the mode frequency. I make sure to then normalize the filter to 1 at the mode frequency when I get the right poles.
- Adjust the "+60 deg" filter in the same way, just shooting for +60+/-5[deg]. Remember to normalize to 1 a the the desired mode frequency.
- Save the foton file, load it into the bank.
- Turn on the bandpass, and set a gain, watching the output of the filter bank on a StripTool. 
- Start with gains of 10-100, but you won't see action until about a gain of 1000.
- Change the sign and phase as normal to find which combination creates damping.

Design at 2k and 2.5k should be pretty darn similar, once you make a starter band-pass and +/-60 deg phase filters.

The attached shows the result of our work at 1k and 1.5k this evening.

I left all of the damping filters I've designed on and running. These should get blown away if we lose lock, so now harm done. Plus there's always the SDF system.

TITLE: 07/07 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Earthquake
INCOMING OPERATOR: Jeff
SHIFT SUMMARY: locked - damping violins
LOG:

• JeffK to EX to reset HEPI pump, and here all shift to work on damping violins
• Bubba on site at LSB 2:45-3:30UTC
• H1 currently locked in Violin Mode Damping 2
• I've increased the bounce mode damping gains to 0.5 (0.1 nominal) and the roll mode damping gains to 30 (20 nominal)

J. Kissel, C. Vorvick, H. Radkins (remotely)

While struggling to damping 2nd harmonic violin modes having just transitioned to DC readout for the first time after yesterday's Montana earthquake, the X-END seismic system suddenly tripped all three stages of its watchdog (ISI ETMX ST1 ST2, and HEPI). Totally unrelated random other problem to solve.

The ISI and HEPI overview screen quickly revealed that the HEPI pump station pressure was NOT OK. A call in to Hugh helped us realize this was a re-occurrence of an over voltage error of that pump station's Variable Frequency Drive (VFD) system (see previous occurences -- seemingly once a year in the summer -- documented in LHO aLOGs 29113, 28653, 12337, 7536).

To fix, I followed the recipes described in the above mentioned aLOGs, repeated here for clarity and a refresher:
- DO NOT UNTRIP HEPI Watchdog! Untripping the ISI watchdogs are fine, but if you haven't changed the SEI manager state, as soon as you untrip all watchdogs, the manager will trying to bring everything back up, and you can't without pump pressure.
- On HEPI Pump Controller MEDM screen, switch pump controller's PID loop over to Manual, ramp down "Manual State Output Tweak" by selecting any large "Count Size Tweak" (say, 10s or 100s) and hitting the "-" until to output (H1:HPI-PUMP_EX_CONTROL_VOUT) reads zero (it was frozen at the max output of 2048).
- Drive to end station (bring CDS laptop!!), turn on wireless network once there, by plugging the dangling red cable into the bottom right most ethernet switch port.
- Head into pump controller room with big flathead screw driver. 
- Confirm that HEPI pump controller box shows a green heartbeat blinking light, and a red "status OK" light.
- Confirm that the translucent fluid in the pump fluid indicator is around 8.5 inches (there's a ruler built into the side of the indicator). Don't be fooled by the little red level indicator thing, those aren't the droids for which you're looking.
- Open up big gray VFD control box (Hugh calls it a "DD box" ...), but confirm on your way that the big 60's NASA light is on (it's RED when ON and OK)
- The VFD controller shows a red "OU3" on its top digital LED display.
- Hit RESET button in bottom, left corner, hit FWD in upper right corner of keypad. "OU3" should change to "0.00", and the green LED screen should read RUN. Nothing else will happen until you start increasing the State Output Tweak again.
- From you CDS laptop, back on the HEPI pump controller overview, set "Count Size Tweak" to 10s, and slowly (one click every 5-10 [s]) click "+" above "Manual State Output Tweak" to increase differential pressure readout (H1:HPI-PUMP_EX_DIFF_PRESS) to 70 [PSI] (a red trace will begin to appear on the long black window once you get it within range ~1-2 [PSI] of the nominal 70)
- Once you get above ~50 ish [PSI] you can click a little faster, we're just looking to prevent large turn-on transients in the servo which'll move the platform.
- Once you're close (within 10 [PSI]) you can flip the PID back over to manual.
- Once the pressure is with 1-2 [PSI] of nominal, untrip the HEPI and ISI watchdogs.

Pictures of all of these things can be found in the above referenced aLOGs.