rana.adhikari@LIGO.ORG - posted 09:40, Friday 22 June 2012 - last comment - 11:11, Friday 22 June 2012(3223)
Amplitude Spectrum of Baffle PD signals (60 Hz)
This PDF shows that the RMS of the PD signals is dominated by 60 Hz + harmonics as we suspected. Unfortunately, it looks like we would have to notch out many, many harmonics to appreciably reduce the RMS. Perhaps we should use a low pass in combo with some comb filters?
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In order to reduce the noise in the channel, I added a Comb filter into the CS_CHAN_NN filter banks to knock down the first 8 harmonics. Also added a 2nd order Butterworth low pass at 11 Hz to get rid of the HF harmonics. The RMS was reduced by 100x.
Restarted the rotating lissajous search pattern on the ALS table PZTs, but still now blips seen in the baffle PD times series...
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