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Entry  Fri Jan 4 19:04:29 2019, awade, DailyProgress, RFAM, Time to look at RF AM and RIN 
    Reply  Wed Jan 9 17:25:38 2019, anchal, DailyProgress, RFAM, Time to look at RF AM and RIN RIN_DBN_Coherence_Measurement.pdf
       Reply  Wed Jan 9 19:05:56 2019, anchal, DailyProgress, RFAM, Time to look at RF AM and RIN 
          Reply  Thu Jan 10 11:38:53 2019, awade, DailyProgress, RFAM, Time to look at RF AM and RIN 
             Reply  Thu Jan 10 17:30:24 2019, anchal, DailyProgress, RFAM, Time to look at RF AM and RIN 
                Reply  Thu Jan 10 18:52:20 2019, anchal, DailyProgress, RFAM, Time to look at RF AM and RIN 
                   Reply  Sat Jan 12 13:11:02 2019, awade, DailyProgress, RFAM, Time to look at beatnote after RF AM and RIN tuneup 
                      Reply  Wed Jan 16 11:07:41 2019, anchal, DailyProgress, NoiseBudget, Beatnote after RF AM and RIN tuneup LaserPowerNoise_to_BNFreqNoise_TF.pdfIN_to_BN_TF.zipTransmission_RIN_Jan15_2019.pdfRIN_Measurement_20190115.zip20190116_130937noiseBudget.pdf
    Reply  Thu Jan 10 14:19:46 2019, anchal, DailyProgress, RFAM, Time to look at RF AM and RIN 
Message ID: 2280     Entry time: Thu Jan 10 17:30:24 2019     In reply to: 2278     Reply to this: 2281
Author: anchal 
Type: DailyProgress 
Category: RFAM 
Subject: Time to look at RF AM and RIN 

We measured the modulation index of 0.142 rad when we installed the PMC (See PSL:2251). I checked both PMC loops, none of them are oscillating.

I think I understand now what is happening. The Amplitude modulation from EOM behind the PMC is about -21 dBm . From Evan's earlier calculations , this RF AM should be suppressed by 0.02 only since it is at 14.75 MHz. This corresponds to -34 dB and hence we are seeing a 29.5 MHz amplitude modulaion ahead of about -55 dBm. There is some mechanism which is frequency doubling this modulation and we are seeing it at 29.5 MHz after the PMC.

I think I will try reducing this RFAM with a combination of PBS and tuning both polarizer and EOM angles. But if we had an extra resonant 21.5 MHz EOM and RFPD, this problem would completely go away as PMC will be able to reduce the RFAM more effectively there.

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