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Entry  Fri Feb 4 11:10:27 2011, Suresh, Update, Green Locking, VCO PLL Frequency noise VCO_calibration.pngVCO_PLL_Servo.pngVCO_Gain.pngVCO_Transfer_Functions.pngVCO_PLL_Freq_Noise.png
    Reply  Mon Feb 14 00:39:21 2011, rana, suresh, Update, Electronics, VCO Frequency Noise Measurement with the MFD 
       Reply  Thu Feb 17 23:11:40 2011, rana, Update, Electronics, VCO Frequency Noise Measurement with the MFD vco.png
Message ID: 4318     Entry time: Thu Feb 17 23:11:40 2011     In reply to: 4281
Author: rana 
Type: Update 
Category: Electronics 
Subject: VCO Frequency Noise Measurement with the MFD 

This is the 140 ft. MFD measurement of the VCO phase noise. It is open loop and so should be a good measurement. The RMS is 30 Hz integrated down to 2 mHz.

I don't know why this doesn't agree with Suresh's measurements of the same thing which uses the PLL feedback method.

In BLUE, I also plot the frequency noise measured by using a Stanford DS345 30 MHz func. generator. I think that this is actually the noise of the FD (i.e. the SR560 preamp) and not the DS345. Mainly, it just tells you that the PINK VCO noise measurement is a real measurement.

I calibrated it by putting in a 5 kHz_pp triangle wave on the sweep of the DS345 and counting the counts in DV.

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