1. Transfer function measurements.
I tried to measure the transfer function from floor at the OMC chamber to geophone/OMC LSC error/DARM.
But the response function of the seismometer above 100 Hz would not flat, we need to reconstruct the signals (Fig.1.).
2. PEM injection using OMC shaker
2025/04/14 7:25:00 - 08:08:00 Large Shaker OMC floor
Excitation : K1:PEM-EXCITATION_SR3_RACK_7_EXC
50 - 400 Hz , 1Hz resolution, 10 s in each measurement, 300 cnt
But I noticed the sweep type was logarithmic (It would be much difficult to evaluate the response function) we stopped the measurement (Fig.2.).
3. 2. PEM injection using OMC shaker
2025/04/14 8:09:00 - 08:40:00 Large Shaker OMC floor
Excitation : K1:PEM-EXCITATION_SR3_RACK_7_EXC
50 - 200 Hz , 1Hz resolution, 10 s in each measurement, 500 cnt
In many frequencies, there are frequency conversion noise, that may come from the large peak in OMC LSC error signal with injection frequency.
We need carefully check it!
