Sheila, Alexa, Stefan

In the afternoon we were fighting higher than usual winds, which troubled us in two ways: excess ETMX pitch motion at its pitch frequency, and ISI blend filter excess noise around 0.05Hz X direction, leading to a saturation of the PDH error signal. We implemented two patches:

1) We re-engaged the ETMX oplev damping. This did a good job at suppressing the ETMX pitch eigenmode.
2) We realized that increasing the tidal feed-back to HPI won't help us with the ISI-induced motion at 0.05Hz - the blend filters will by design start isolating the test mass, limiting our tidal UGF. Thus we switched back to ETMX top mass feed-back, and added a broad resonant gain (see snapshot) around 0.05Hz. This seemed to get us about a factor of two in range for the green PDH lock - just enough to prevent saturation.
3) Right after implementing this, the winds also started to come down.

With this we started looking at the COMM_handoff script that Sheila and Alexa had put together:
1) We realized that we only had 11deg phase margin. This was due to the bleed-off to the penultimate mass (M1), which effectively acts as a boost filter. Jeff had set it to 7Hz, with a M2_LOCK_L gain of 0.1. I lowered it by 3dB to gain back phase.
2) To gain back more phase margin during the turn-on, we set the the CARM gain initially to 160 (was set at 80). This brings to the x-over UGF to 25Hz, and lots of phase.
3) After the hand-off the CARM gain is again lowered to 100 (x-over UGF of 17Hz) to allow turning on the roll and bounce mode notches in MC2.
4) Finally the script now also turns on the CM BOOS (compensation) filter and the end.
5) I also uncommented the initial ezcaservo, the read statement, and the gain stepping. For the latter I also increased the step-wait time to 0.3sec because unmatched electronic offsets in the gain steps tend to ring the mode cleaner for a little bit.


Attached are
1) A snapshot of the filter settings for the ETMX pitch OL filter and the tidal feed-back loop.
2) The ALS-COMM x-over OLG measurement - the inal setting is four dB lower than the measurement (see cursor).
3) ETM optical lever and green PDH control signals (uncalibrated). 


Below is a copy of the current COMM_handoff script - it is ready for a Guardian now:
#!/bin/bash

ezcaservo -t 10 -s 0 -g -1 -f 0.1 -r H1:ALS-C_COMM_PLL_CTRLMON H1:IMC-VCO_TUNEOFS &
sleep 2
#COMM PLL boost OFF
caput H1:ALS-C_COMM_PLL_BOOST 0

#prepare CARM
ezcaswitch H1:LSC-CARM FMALL OFF FM8 FM1 ON
#caput H1:LSC-CARM_GAIN 80
# initally to 160 for extra stability during power increase (Stefan 20140213)
caput H1:LSC-CARM_GAIN 160

#prepare AO path
caput H1:IMC-REFL_SERVO_IN2POL 0
caput H1:IMC-REFL_SERVO_IN2GAIN 16
caput H1:IMC-REFL_SERVO_IN2EN 1

#prepare refl board
caput H1:LSC-REFL_SERVO_IN1GAIN -32 
caput H1:LSC-REFL_SERVO_IN1EN 1
caput H1:LSC-REFL_SERVO_FASTGAIN 6

#prepare MC2
caput H1:SUS-MC2_M3_LOCK_L_LIMIT 6400000
caput H1:LSC-MC_TRAMP 2
ezcaswitch H1:SUS-MC2_M3_ISCINF_L FM6 FM7 OFF
sleep 2

#turn down MCL DC gain
ezcaswitch H1:LSC-MC FM1 ON
#echo "Press enter to continue"
#read
#turn up COMM gain
# Reduced to 0.3sec steps - IMC was ringing a bit (Stefan 20140213)
ezcastep -s 0.3 H1:LSC-REFL_SERVO_IN1GAIN +1,41
#used to be 32 steps

#low frequency boost
ezcaswitch H1:LSC-CARM FM5 ON 
# CARM gain to 100 - middle of phase bubble (Stefan 20140213)
caput H1:LSC-CARM_GAIN 100
sleep 2
# turn the MCL feedback off
caput H1:LSC-MC_GAIN 0
# make the CARM boost up
ezcaswitch H1:LSC-CARM FM4 ON


ezcaswitch H1:SUS-MC2_M3_ISCINF_L FM6 FM7 ON
ezcaswitch H1:SUS-MC2_M3_LOCK_L FM3 OFF
#COMM PLL boost 
caput H1:ALS-C_COMM_PLL_BOOST 1

# CM board BOOST (compensation) ON  (Stefan 20140213)
caput H1:LSC-REFL_SERVO_COMCOMP 1