The UGF servo for PRCL is working. For the moment being I'm injecting a line at 52.1 Hz. The plan is to track the evolution of the PRCL gain over a few locks. Hopefully we can then hard code the gain changes over thermalization and get rid of the gain servo.
The servo has a time constant of about one minute.
All parameters have been saved to SDF safe. Except:
- line amplitude H1:LSC-PRCL_UGF_OSC_CLKGAIN = 10
- servo input switch H1:LSC-PRCL_UGF_SERVO_SW1
- servo master switch H1:LSC-PRCL_UGF_MASTER
Trend of PRCL UGF servo over 1.5 h of lock. Both signals are in db.
It looks like the servo is still too slow to cope with fast changing PRCL optical gain.
The optical gain changed by 6 db over the time in the trend and it's still changing
The PRCL servo is turned on in LOWNOISE_LENGHT_CONTROL and off in DOWN.
We'll leave it on for a few locks to see the trend. We don't want to leave it on longterm, since we are now injecting a huge 52.1 Hz line to measure the UGF.