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Entry  Mon Aug 16 14:19:00 2010, Alastair, Laser, GYRO, Changed to Marconi on AOM gyro_transmission_08_16_10.pdf
    Reply  Mon Aug 16 15:31:27 2010, Zach, Laser, GYRO, Changed to Marconi on AOM 
    Reply  Tue Aug 17 10:18:02 2010, rana, Laser, GYRO, Changed to Marconi on AOM 
       Reply  Tue Aug 17 15:34:02 2010, Alastair, Laser, GYRO, Changed to Marconi on AOM gyro_transmission_08_17_10.pdf
          Reply  Wed Aug 18 03:01:23 2010, rana, Laser, GYRO, Excess noise mystery resolved 
             Reply  Wed Aug 18 10:31:28 2010, Alastair, Laser, GYRO, Excess noise mystery resolved 
Message ID: 942     Entry time: Tue Aug 17 15:34:02 2010     In reply to: 941     Reply to this: 943
Author: Alastair 
Type: Laser 
Category: GYRO 
Subject: Changed to Marconi on AOM 

Quote:

Its amazing if it turns out that the noise goes down that much with just turning off the feedback on the CW path. Is it really repeatable, or is it just that the CW beam was not resonating and therefore not producing a beat signal in the transmisssion?

 I have repeated the measurement here.  I began by measuring the transmission signal on an analyzer with the modulation on and off. With it on we're getting -26.5dBV at 95.021MHz.  With the Tektronix set to continuous we're getting -26.6dBV at 95.019MHz.

I then repeated the noise measurement with the PLL to check that I didn't make a mistake yesterday.  I made sure both directions looked locked on the CRT while taking the data and afterwards plugged the output back into the analyzer and measured the peak to be -27.1dBV.  The plot is below.  We're still seeing the large drop in noise with the modulation off.

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