This is an update of the OMC Length noise projection using the 2024-11-11 data.

In the previous work, I evaluated the transfer functions of  (OMC Length) -> (OMC DC PC) and  (OMC Length)^2 -> (OMC DC PC), but the projection of these noises was not good because the OMC Error signal was not the pure actual OMC length due to being affected by the sensing noise.

To remove the sensing noise, I applied FFT -> filtering -> iFFT (->Square in the time domain).
Here this filtering is 1/100 gain for the frequencies whose amplitude (with moving average) is less than 3e-6. [Fig.1]

Fig.2 shows the ASDs of the linear and the squared time-series, beforehand after the filtering.
Fig.2 shows the projection on the DCPD signal, using these ASDs and the TFs evaluated before.