jim.warner@LIGO.ORG - posted 00:38, Thursday 02 February 2017 - last comment - 07:14, Thursday 02 February 2017(33832)
Shift Summary
TITLE: 02/02 Eve Shift: 00:00-08:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 66Mpc
INCOMING OPERATOR: Nutsinee
SHIFT SUMMARY: PI's bad, finally back to observing
LOG:
Couldn't stay locked because of PI. I made new band passes to deal with shifted modes. Didn't realize there is a PLL frequency that also needs to be adjusted when you change the band pass filter. It's kind of buried in the middle of another step on the PI wiki. The PLL shouldn't have locked with this frequency too mismatched (how close is close enough?), but I could have swore I saw the PLL lock light going green. Nutsinee found and adjusted it, seems good now.
Thanks Jim, and sorry for the not-obvious PLL thing in the wiki.
As far as setting the PLL frequency, within a Hz should be close enough.
I'm sure you did see the PLL lock light going green before: it could've been locking on some other smaller peak and then unlocking and relocking, or once your PI rings up huge enough the PLL could've locked on the right peak, but by then it was too big to damp.