J. Kissel, S. Dwyer

When we apply a large SRCL offset, as we did today LHO:83583, we get more 45 MHz sideband field in the POP port. The POP A LSC RFPD (in HAM1) is demodulated in analog at 45 MHz, and its I & Q signals are piped into a standard 16 bit ADC whose saturation limit is +/- 2^15 = 32768 [ct]. The I channel is used as the error signal for SRCL, and the Q is used as the error signal for MICH, so if we get anywhere near that saturation limit, these loops lose there error signals and the IFO loses lock.

So, just a sanity check, here's the POP A I & Q raw ADC channels across the transition from -191 [ct] to -306 [ct] SRCL offset.

-306 [ct] does not saturate the POP A I or Q ADC channels.