The SR570 (not 560) current preamp that we had been using since yesterday afternoon for channel 27 of the baffling diodes, ran out of batteries today at around 1330 today (so we know that a fully charged one will last just under 24 hours).

At that point it started producing glitches of ~30000 cts in channel 27 with a steady ~4 second period. Because of some grounding issue somewhere, it also produced smaller glitches in the other 3 channels. These glitches looked somewhat like a widly swinging green beam, so I spent a little while investigating the health of the various seismic filtering servos for the ETMY/ITMY before guessing that it was too regular to be mechanical.

Preamp has been switched back to the Melles Griot 13AMP003 "Large Dynamic Range" Amplifiers that the other channels are read out with. The SR570 on batteries was nicer than these; with a little bit of thought, I guess we could figure out how to adapt the ISC QPD readout board into one that can be used for this application (FET preamps, high transimpedance, some low pass fitlering) and then switched out to a lower gain one once we get into real interferometer locking.

After swapping, I used ezcaservo to remove the offsets on all the channels using commands like this one:

ezcaservo -r H2:PEM-CS_CHAN_27_OUT16 -g -0.21 H2:PEM-CS_CHAN_27_OFFSET -t 20