J. Kissel
IIET Ticket 31266

Conversations are still brewing about what to do about DuoTone timing signals showing up in DARM -- presumably through the OMC DCPD's ADC card (see LHO:77579). Recall that we've narrowed down the coupling mechanism to direct channel-to-channel cross coupling within the ADC (see LHO:78238). As such, one of the options on the table is to reduce the amplitude of the DuoTone timing signal, which is using 1/4 of the ADC channel's range at 5 [V_pp], rather loud, IMHO (see LHO:78218). 

Daniel and Erik did a whole bunch of work at the start of O4 to get the front-end-code computed ADC timing measure more accurately reporting and answer with a better algorithm in the front-end (see LHO:67693 and LHO:67545), so I figured I show the trend of a few important front-end's answers, since I haven't seen such a trend:
    (1) the h1omc0 segregated IO chassis which houses the GW DCPDs,
    (2) the h1lsc0 computer which *used* to house the DCPDs prior to O4.
    (3 & 4) the two end-station ISC computers which house, among other things, the PCAL systems.

The answers from the long-term trend: 
    (1) 0.12 +/- 0.035 or +/- 0.08 [usec]
    (2) 7.05 +/- 0.031 or +/- 0.06 [usec]
    (3) 61.6 +/- 0.15  or +/- 0.31 [usec]
    (4) 61.6 +/- 0.15  or +/- 0.31 [usec]
where I'm eye-balling (via y-cursor at least) the long-term trend of the mean, the middle of the max/min excursions, and the worst of the max/min excursions.
These answers (the means) are all expected, but it's good to have some numbers on the max / min excursions, which are, presumably, noise.

Zoom in closer, one can see on the minute time scale trend of a gravitational wave event, the estimation of the timing error is about as precise.