Attached is a screenshot showing a PRCL injection with and without the PRCL offset of -62 in PRCL1.
PRCL offset off: 6/5/2024 17:19:13 UTC
PRCL offset on: 6/5/2024 17:09:19 UTC
The PRCL offset doesn't make much of a difference to the DARM coupling, it may be a little worse with the offset off below 17Hz but a little better above 30 Hz.
I've edited the guardian to no longer have this offset on, because there doesn't seem to be a strong motivation for it and we'd preffer not to have these digital offsets in.
In today's commissoning time, I first did the above measurements of PRCL coupling with and without the offset on, then later readjusted the SRCL gain ( 77648). Below is a comparison of PRCL coherence with DARM before and after these changes (PRCL offset off, seems to have no impact, and SRCL FF retuned). It seems that by retuning the SRCL FF, we have reduced the PRCL coherence with DARM. Also shown is the PRCL coherence with SRCL, which is high at all frequencies.
In 77289 we reduced the PRCL coupling to SRCL and the MICH by phasing POP45 and retuning the LSC input matrix. These didn't improve the PRCL coupling to DARM.
