An accelerometer (JGW) was installed on the PSL optical table near the reference cavity. You can see small box (roughly 1cm square) connected to the white cable in the attached picture.
K1:PSL-TTFSS-COUT1 channel, which is not used anymore, is connected to accelerometer temporarily, so the real time model should be modified at some point.

The  attached plot is the spectrum with KOACH filter and air conditioner on/off. Obviously there are noises caused by KOACH filter around 100 Hz and 1kHz .
I guess the other area is the sensor noise. Kirii-kun would measure the noise level in next week, so it would be turned out.