40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  ATF eLog  Not logged in ELOG logo
Entry  Mon Mar 22 15:01:24 2010, Dmass, Laser, ISS, ISS Spectra ISSILandOL.pdfGreenPDsBudget.pngIRPDsBudget.pngPDSubtracAll.pdf
    Reply  Tue Mar 23 15:01:29 2010, Dmass, Laser, ISS, ISS Spectra SubtractTestCoh.pdfSubtractTest.pdf
       Reply  Tue Mar 23 17:05:11 2010, Dmass, Laser, ISS, ISS Spectra 
          Reply  Tue Mar 23 21:24:57 2010, Dmass, Laser, ISS, ISS Spectra 
             Reply  Wed Mar 24 00:09:39 2010, Dmass, Laser, ISS, ISS Spectra 
                Reply  Wed Mar 24 22:12:49 2010, Mott, Laser, ISS, fb0 error 
                   Reply  Fri Mar 26 17:05:43 2010, Mott, Laser, ISS, fb0 error 
                      Reply  Tue Mar 30 16:44:20 2010, Mott, Laser, ISS, fb0 error 
                         Reply  Fri Apr 9 11:35:56 2010, Mott, Laser, ISS, fb0 error 
    Reply  Thu Mar 25 02:06:53 2010, Dmass, Laser, ISS, ISS Spectra 
       Reply  Thu Mar 25 02:38:54 2010, Koji, Laser, ISS, ISS Spectra 
          Reply  Thu Mar 25 10:38:24 2010, mevans, Laser, ISS, ISS Spectra 
          Reply  Thu Mar 25 13:29:18 2010, Dmass, Laser, ISS, ISS Spectra 
             Reply  Thu Mar 25 14:16:32 2010, Dmass, Laser, ISS, MZ Spectra! rawdata.zipLockedPhaseNoise.pdf
Message ID: 698     Entry time: Tue Mar 23 15:01:29 2010     In reply to: 690     Reply to this: 699
Author: Dmass 
Type: Laser 
Category: ISS 
Subject: ISS Spectra 

On Hartmut's suggestion, I have tested my subtraction algorithm.

  • I took the raw spectra of on of the IR PDs (PD3).
  • I generated two white time series via MATLAB's "rand" function at a level of several below the "signal floor" of this spectrum
  • I added this to the PD3 time series to generate the
  • I subtracted one noisy time series from the other.
  • I recovered the subtraction I expect from the noise levels, and this is consistent with the predicted subtraction based on the coherence

I have shorted the green PDs together after the transimpedance amplifier, and the IR PDs together before the buffer I made (after the ISS PD box). I will check if the problem is upstream of the ADC next, since the subtraction works. Hopefully I find some electronics shenanigans, and won't be able to subtract the two identical PD spectra

Attachment 1: SubtractTestCoh.pdf  135 kB  Uploaded Tue Mar 23 16:34:15 2010  | Hide | Hide all
SubtractTestCoh.pdf
Attachment 2: SubtractTest.pdf  75 kB  Uploaded Tue Mar 23 16:35:58 2010  | Hide | Hide all
SubtractTest.pdf
ELOG V3.1.3-