Richard, Fil, Daniel
We are using the spare channel on the IMC demod board for REFL_B. This 2-chn demod has the new interface board which implements whitened readbacks for I and Q. The DB9 cable to the ADC was borrowed from the 4th port of the WFS interface in ISC-R4 (ISC_425). This port was never used.
Channels names are H1:LSC-REFL_B_RF9_I_ERR and H1:LSC-REFL_B_RF9_Q_ERR. We also get H1:IMC-REFL_RF24_I_ERR and H1:IMC-REFL_RF24_Q_ERR for free.
The 9.1 MHz LO is hooked up through a delay line. I measured 10dBm at the input to the LO. Earlier today the out-of-vacuum cables to the HAM1 flange were installed as well. The DC readback is through the 2nd port of the LSC PD interface in ISC-R1. The channel name is H1:LSC-REFL_B_LF_OUT. A separate RIN channel is also available.
Injected an RF signal into the RF input of the demod and checked that the readbacks and whitening are working. The whitening is 2 zeros at 2.98Hz and 2 complex poles at 30Hz with a Q of 0.57. The low frequency gain is 1, whereas the high frequency gain is 40.1dB.