Ansel, Sheila, Camilla
Last week, Ansel noticed that there is a 2Hz comb in DARM since the break, similar to that that we've seen from the HWS camera sync frequency and power supplies and fixed in 75876. The cabling has not been changed since, the camera sync frequency has been changed.
Our current camera sync frequencies are: ITMX = 2Hz, ITMY = 10Hz. We have typically seen these combs in H1:PEM-CS_MAG_LVEA_OUTPUTOPTICS_Y_DQ. With a 0.0005Hz BW on DTT I can't easily see these combs, see attached.
It may be difficult to see in a standard spectrum, but can be clearly seen in Fscan plots linked off of the summary pages. For the "observing" Fscan, the interactive spectrum plot shows the 2 Hz comb marked automatically. See the attached image of H1:GDS-CALIB_STRAIN_CLEAN
Verifed that the cabling has not changed since 75876.
Next steps we should follow, as listed in 75876 would be to try using a different power supply or lowering the voltage to +12V. Or, there is a note suggesting Fil could make a new cable to power both the camera and CLink's via the external supply (14V is fine for both).
Thanks Camilla. If anything can be done more rapidly than waiting another week, it would be very much appreciated. Continuing to collect contaminated data is bad for CW searches.