The front-end calculation of the Pcal X/Y calibration comparison factor, chi_XY (H1:CAL-CS_TDEP_PCAL_X_OVER_Y_REL_MAG), now seems to be working as designed after correcting an error in one of the demod frequencies yesterday afternon.

The first attached plot shows the calculated value during a ~2 hour long lock stretch last night.  Ideally, the value should be unity.  The mean value over this two-hour interval is close to 1.0, with variations of about plus/minus 0.0030.  These variations may result from non-optimial filtering in the on-line calculation.  Investigating and optimizing this front-end calculation and understanding variations in the chi_XY parameter are the subject of a SURF summer student project scheduled to start mid-June.

The second attached image is a screenshot of a diaggui (DTT) session used to make a rough calculation of the parameter by hand.  The calculated value during the same lock stretch (starting at 09:00 UTC on 5/24/2023) is 1.00046.