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Entry  Wed Sep 1 11:34:39 2010, Alberto, Update, Electronics, FSS Box Phase Noise from DAQ 2010-09-01_FSSPhaseNoise.png2010-09-01_FSSphaseNoiseMeasurementSetup.png
    Reply  Wed Sep 1 12:34:14 2010, rana, Update, Electronics, FSS Box Phase Noise from DAQ 
       Reply  Wed Sep 1 16:29:28 2010, Alberto, Update, Electronics, FSS Box Phase Noise from DAQ - Measurement setup modified 2010-09-01_FSSPhaseNoise_DAQ_00-02_comparison.png2010-09-01_FSSPhaseNoise_DAQ_02.pngFSSphaseNoiseMeasurementSetup02.png
          Reply  Wed Sep 1 17:17:42 2010, rana, Update, Electronics, FSS Box Phase Noise from DAQ - Measurement setup modified 
Message ID: 3509     Entry time: Wed Sep 1 16:29:28 2010     In reply to: 3508     Reply to this: 3510
Author: Alberto 
Type: Update 
Category: Electronics 
Subject: FSS Box Phase Noise from DAQ - Measurement setup modified 

Quote:

The differences between this setup and the one used previously is the lack of the 50 Ohm terminator in the mixer output and

that the SR560 readout with the G=100 should come before the first SR560 via T, so as not to be spoiled by the high noise of the G=1 SR560.

I removed the 50 Ohm in-line terminator when I did the measurement with the SR785. The for some reason I was getting more noise, so I removed it.

Now I put it back in and I did the measurement with the DAQ. I also moved the SR560 that amplifies the signal for the DAQ, Tee'ing it with the input of the in-loop SR560.

Now the setup looks like this:

FSSphaseNoiseMeasurementSetup02.png

And the phase noise that I measure is this:

2010-09-01_FSSPhaseNoise_DAQ_02.png

Comparing it with the phase noise measured with the previous setup (see entry 3506), you can see that the noise effectively is reduced by about a factor of 2 above 10 Hz.

2010-09-01_FSSPhaseNoise_DAQ_00-02_comparison.png

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