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Entry  Thu Apr 28 15:23:11 2016, ericq, Update, LSC, Green PDH demod lowpass 
    Reply  Thu Apr 28 18:53:05 2016, rana, Update, LSC, Green PDH demod lowpass 
       Reply  Fri Apr 29 16:13:36 2016, ericq, Update, LSC, Green PDH demod lowpass IMG_3186.jpgpdh_lpf.pngelp_liso.zip
          Reply  Fri May 6 16:42:12 2016, ericq, Update, LSC, Green PDH demod lowpass pdh_lpf.pngAUX_X_PDH_OLG_May6.png
             Reply  Fri May 6 19:08:52 2016, rana, Update, LSC, Green PDH demod lowpass 
                Reply  Sat May 7 09:40:40 2016, ericq, Update, LSC, Green PDH demod lowpass 
                   Reply  Sun May 8 08:39:21 2016, rana, Update, LSC, Green PDH demod lowpass 
Message ID: 12113     Entry time: Sun May 8 08:39:21 2016     In reply to: 12112
Author: rana 
Type: Update 
Category: LSC 
Subject: Green PDH demod lowpass 

Indeed. This is why the LSC PDs have a 2f notch in addition to the 1f resonance. In recent versions, we also put a 2f notch in the feedback of the preamp which comes after the diode but before the mixer. The overall 1f to 2f ratio that we get is in the 50-60 dB region. I don't think we have to go that far with this thing; having a double LC already seems like it should be pretty good, or we could have a single LC bandpass with a 2f notch all in one Pomona box.

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