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Entry  Wed Apr 24 16:01:55 2019, anchal, DailyProgress, FSS, Time series and spectrum analysis of RFout of SCavReflRFPD near resonance South_Cavity_Reflection_RFout_Time_Series_Analysis.pdfSouth_Cavity_Reflection_RFout_Spectrum_Analysis.pdf
    Reply  Fri Apr 26 14:34:03 2019, anchal, DailyProgress, FSS, Time series and spectrum analysis of RFout of SCavReflRFPD near resonance 
       Reply  Sun Apr 28 22:31:39 2019, rana, DailyProgress, FSS, RF beats 
          Reply  Tue Apr 30 18:07:49 2019, anchal, DailyProgress, FSS, Spectrum of RFout from South Cavity Reflection RFPD SCavReflRFoutSpecAnalysis.pdf
             Reply  Wed May 8 20:03:43 2019, anchal, DailyProgress, FSS, FSS PDH Error Signal on South Path is in good health SCavPDHError20190508.pdfCavity_Refl_RFPD_TI_After_Modifications.pdf
Message ID: 2328     Entry time: Fri Apr 26 14:34:03 2019     In reply to: 2326     Reply to this: 2330
Author: anchal 
Type: DailyProgress 
Category: FSS 
Subject: Time series and spectrum analysis of RFout of SCavReflRFPD near resonance 

I think I figured the source of this 281 kHz peak. 281 kHz  ≈ 37 MHz - 36.72 MHz, so it is the beat signal between 37 MHz and the 36.72 MHz signals. I think I should tune the RFPD more next time I open the cage to bring its resonance closer to 37 MHz.

Quote:
  • Next, I took a board spectrum from 0-500 kHz to spot that 290kHz we saw in time series data. Indeed there is a peak at 281 kHz of -66.36 dBm. This looked like a bigger oscillation in time series (~50 mVpp => -22 dBm but again, this data taking method is not really good). There are other nearby peaks at ~269 kHz and 2~284 kHz. I'm not sure why these peaks are here. But they can not be some standing wave in the cable as it will require ~700m long cable.
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