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Entry  Sat Feb 16 18:32:01 2013, yuta, Summary, RF System, phase tracker: OLTF BEATXFINEPHASE_OLTF.pngBEATYFINEPHASE_OLTF.pngphasetracker.png
    Reply  Thu Feb 28 05:54:54 2013, yuta, Update, RF System, phase tracker: calibration ALS-BEATX_FINE_PHASE_OUT.pngALS-BEATY_FINE_PHASE_OUT.png
       Reply  Thu Feb 28 06:51:17 2013, yuta, Update, RF System, phase tracker: noise level frequencynoise.png
          Reply  Sat Mar 2 20:09:12 2013, yuta, Update, RF System, phase tracker: DAQ noise limited frequencynoisewhitening.png
Message ID: 8200     Entry time: Thu Feb 28 06:51:17 2013     In reply to: 8199     Reply to this: 8214
Author: yuta 
Type: Update 
Category: RF System 
Subject: phase tracker: noise level 

I measured noise level of the phase tracker by inputting constant frequency RF signal from marconi.
Measured frequency noise was ~2 Hz/rtHz @ 100 Hz. It's not so good.

What I did:
  1. Unplugged 11MHz marconi and put RF signal to the beatbox from this. Frequency and amplitude I put are 100 MHz and -3 dBm.
  2. Measured spectra of phase tracker outputs, C1:ALS-BEATX_FINE_PHASE_OUT, C1:ALS-BEATY_FINE_PHASE_OUT.
  3. Calibrated using the factor I measured (elog #8199).
  4. Put marconi back to orignal settings.

Result:
frequencynoise.png

Discussion:
  - According to Schilt et al., this noise level is not so good.
  - By changing the delay-line cable length or optimizing whitening filter etc., we can improve this.
 

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