[Sheila, Jenne]
Usually when we are doing calibration-type measurements, we go to our NLN_CAL_MEAS state, which turns off the calibration lines as well as the ADS lines and loops. Sheila had noted in the past that when we go to this state, our 60 Hz glitches seem to go away. That was again true today.
I wanted to look at some calibration things while Sheila was doing her measurements, so I took us back to NomLowNoise (which turned all the lines back on) then I hand-turned off the ADS lines and loops. With this situation (cal lines on, ADS lines off) we see our little train of 60Hz glitches. We don't know right now which line is causing them, but this does narrow it down to being related to the cal lines.
In the attached figure, I turned the cal lines back on around -14 min, and you can see the 60Hz glitches present after that time.
22:40 UTC, turned off PCalX line at 2.5kHz, to see what the 60Hz glitches do. Note that we are still in commissioning mode for scheduled noise budget injections.
With just PcalX off, the glitches are still present. At 22:57 I turned off the PcalY lines.
23:05, turning both PcalX and PcalY lines back on.
With all of the PcalY lines off, the glitches seem to be gone. So, I think this exonerates the suspension calibration lines, and we could in the future try to determine if it is any one specific PcalY line, and decide what to do about it.
While Jeff B took us out of observing to deal with a violin mode quickly, Jenne and I turned off the excitation for the 7.93 Hz pcal Y line for 4 minutes from 16:21:20 to 16:25:30 UTC April 19th. The glitches around 60Hz seemed to be gone when this was off.
Also, to note, moving the frequencies of lines 1+2 48551 doesn't seem to have had much of an impact on these glitches, you can compare dmt omega plots from the summary pages before and after the change.
