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Message ID: 1040     Entry time: Thu Sep 9 23:36:53 2010
Author: Zach 
Type: Misc 
Category: GYRO 
Subject: gyro noise budget updated in SVN 

 I have updated 'noisebud.m' in the gyro SVN to include the MZ noise measured on the gyro table. It has been plugged into the FSR modulation section, where we used to have the noise from the 40m MZ. I have also suppressed the plotting of the following traces:

  1. Mechanical noise modulating the earth rotation signal --- this will always be weaker than the FSR modulation, unless we switch to a cavity with an FSR of ~30Hz.
  2. Old Marconi noise trace --- this has since been replaced by a newer, correct measurement, though the old trace was never removed.
  3. Old Isomet noise trace --- this has not been revisited, but I assume it is also wrong, as it was calculated in the same way as (2).

I have not removed any of the calculations for the above, but only the plotting instructions. We should decide if they need to be kept in any form or discarded for good.

I am working on a detailed analysis of how cavity mirror displacement noise couples into the gyro signal, as I suspect more than just the one pathway. Once we have all agreed on how it works, I will update the GyroDoc itself.

NOTE: The gyro MZ noise spectrum is DC - 10kHz @ 0.01 Hz BW = 1 million pts. This results in a big (33 MB) file which slows the running of noisebud. I'm sure there is an easy way to smooth this down but I don't know it off the top of my head and I fear for my life if I do not update the NB tonight.

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