Looking at the data from Sept 25th around 16h15 UTC (logbook 42949) with the IRIG-B sent to the B1p_PD1 and B1_PD2 photodiodes, and other standard data, we found the following delays for B1 and B1p sensing to be taken into account in the calibration.

B1p

The first table gives the delays measured for B1p_PD1 channels, to be taken into accont in the actuation measurements in free swinging Michelson  (the DC_10kHz channel is an intermediate processed channel in the DeltaL reconstruction of free Michelson data).

Note that during O2, the delay Audio_20kHz/Audio_1MHz was 152 µs.

The 1MHz/GPS delay is -212 µs for B1, B1p and also for the ADC channels in the DAQroom that receive the GPS signals directly. It indicates that there is an extra delay of 200 µs in the timing distribution compared to O2.

B1

The second table gives similar results for B1_PD2 channel, to be taken into account in Hrec process for B1 sensing.

The TF Audio_20kHz/AUdio_1MHz  is different for B1p and for B1 since the anti-alias filters used in SDB2_Photodiode are silghtly different: a simple Butterworth  on B1p signals, and the Butterworth with notches for the OMC on B1 signals.