naoki.aritomi@LIGO.ORG - posted 10:34, Monday 10 June 2024 - last comment - 11:02, Wednesday 12 June 2024(78345)
Turn off FC green VCO lock after FC IR transition
Naoki, Sheila
To investigate the origin of whistles and rms increase in FC IR signal as reported in 78263 and 78344, we turned off the FC green VCO lock after FC IR transition.
In TRANSITION_IR_LOCKING state of SQZ_FC guardian, the FC CMB servo is disabled after FC IR transition. Since we use the green QPD at FC trans for beam spot control, we also turned off the beam spot control. The SDF is accepted as shown in the attachment.
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After this guardian change, FC lost lock after IR transition. I reverted the guardian change and FC lock is fine. The FC CMB input is ON now and it was OFF from 2024/06/10 16:44:06 UTC to 2024/06/11 15:07:58 UTC. The beam spot control is still OFF.