I measured FDS with CCFC (attached figure). The DDS setting for FDS with CCFC is saved as 20210519_dds3_CCFC. During this measurement, CC2 input test mass feedback was engaged with gain of 3.

There is a large peak around 170 Hz introduced by CCFC. I will try to change the filter for CCFC if we can remove the peak.

Unfortunately, the homodyne angles in this measurement are in the wrong side. So I will measure again with correct homodyne angles.