Calibration filter for geophones are copied from ETMX to BS.

The attached is the power spectra of the BS geophone signals.
The brown line is the IY0 seismometer signal roughly calibrated with one pole at 0.01 Hz and gain to have 1/2pi at 1 Hz. (calibration from velocity to displacement.)

The peaks at frequencies higher than 0.3 Hz are likely the resonances of IP. Still, there is a discrepancy between the geophone signals and seismometers.
Ideally, geophone signlas should be smaller than the seismometers on the ground due to the vibration isolation system (The lowest IP resonant mode is about 0.15 Hz.)
We need to check the calibration values.

Also, the noise level is too large to create effective active vibration reduction control filters.
Since the SNR of the seismic motion at around 0.2 Hz is only about 2 or 3 while about 0.1 (noise is 10 times larger than the signal) at around 0.1 Hz, the amount of the noise that would be injected through the control must be larger than the reduction of the seismic motion...

Thinking about the efficient control of IP, we might have to turn on the control only when the micro-seismic motion is so large.
And also we have to think about how large micro-seismic motion can trigger the IP geophone control.