I noticed a strange offset in POP17I used for locking SRY, as shown in the attached. It changed from -0.93 to 0.86 while SRY was freely swinging, so it was slightly off-centred. When locking the SRY using it, AS DC power increased to 0.005, while the maximum power when freely swinging was 0.007. It reached the maximum value when an offset was added to the error signal and it was locked around 0.17, not 0. Probably related to this offset, ADS didn't work well; when it was engaged after locking SRY without any offset on the error signal, AS DC power stayed the same, and nothing changed after tuning the offset.

Last week, we didn't see such an offset; SRY was locked to the carrier resonance without any offset tuning, and ADS seemed to work well. We need further investigation for stable locking of DRMI.