Reports until 18:05, Thursday 08 November 2018
H1 ISC
jenne.driggers@LIGO.ORG - posted 18:05, Thursday 08 November 2018 - last comment - 10:49, Friday 09 November 2018(45137)
Lockloss triggering seems to help violin modes

I put the lockloss triggering into the guardian, such that the PREP_FOR_LOCKING state will force it to be triggered, so we can acquire lock.  Then in DRMI_TO_POP, at the same place that the individual LSC filter banks were getting their lockloss triggers set, I set the IFO trigger to look at LSC-POP_A_DC.  We have had one lockloss with the triggering active, and the next lock had much smaller violin modes. 

When we engaged the violin damping after we hit resonance while still locked on RF, the narrow-band ETMY mode 1 violin almost immediately rang up.  So, we need to be doing a clear history on those before we start locking.  Most of our usual-width filters have step responses a few tens of seconds, but this narrow band one has a step response greater than 3000 seconds.  So, when we relock and turn on that damping (since we aren't doing a clear history right now) that filter still has the lockloss transient in its memory. 

I've now added turning off the inputs and clearing the violin mode histories to the guardian.  The inputs get turned back on in the violin damping Settings state.  We've got an EQ incoming, so I don't think we'll get a chance to see this keep the modes down tonight.

Comments related to this report
jenne.driggers@LIGO.ORG - 10:49, Friday 09 November 2018 (45159)

Clearing the histories after the inputs are off seemed to help - we didn't ring up the bad EY mode this time.  (We also hadn't been locking overnight, but the point is that not sending junk to the mode is better, and seems to prevent it from ringing up needlessly.)