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Entry  Sun Jan 16 02:20:59 2011, Suresh, Update, Locking, comparing the PSL with the X-end-NPRO through the green beat P1160510.JPGP1160511.JPGP1160515.JPGP1160516.JPG
    Reply  Wed Jan 19 03:37:30 2011, Suresh, Update, Locking, comparing the PSL with the X-end-NPRO through the green beat Phase_noise_in_digital_frequency_dividers.pdf
Message ID: 4161     Entry time: Sun Jan 16 02:20:59 2011     Reply to this: 4166
Author: Suresh 
Type: Update 
Category: Locking 
Subject: comparing the PSL with the X-end-NPRO through the green beat 

Objective:

      We wish to study the coherence of the two NPROs i.e. PSL and the X-end-NPRO by locking both of them to the X-arm and then observing the green beat frequency fluctuations. 

What we did:

   a) locked the PSL to the X-arm as described in 4153

   b) locked the x-end-NPRO to the X-arm with a PDH lock to the reflected green from the ETMX

   c) Obtained the green beat signal with a spectrum analyser as described in 3771

Observations:

   Please see the attached screen shots from the spectrum analyser.   They are taken with different BW and sweep range settings.  They give a estimate of the width of the green beat signal and the range of the frequency fluctuations of the beat-note.

P1160510.JPGP1160511.JPGP1160515.JPG

P1160516.JPG

 

Estimates:

   a) width of the beat note is less than 6KHz if measured over time scales of a few milli seconds

   b) the frequency fluctuations of the beat note are about 100KHz over time scales longer than 100ms

Next Step:

    We wish to record the beat note frequency as a function of time in order to establish the stability over time scale of a day.

 

 

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