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Entry  Fri Aug 1 12:49:06 2014, Koji, Summary, IOO, MC servo analysis MC_OLTF.pdfMC_Error_Common.pdfMC_Crossover.pdfMC_CLTF_Fast.pdf
    Reply  Thu Aug 7 11:57:59 2014, Koji, Summary, IOO, MC servo analysis MC_OLTF_Fit.pdfIMC_OLTF.zipMC_OLTF_estimated.pdf
       Reply  Fri Aug 8 12:39:19 2014, ericq, Summary, IOO, MC servo analysis mcLoopAug8.zipMCloopAug8.pdf
          Reply  Fri Aug 8 15:57:29 2014, ericq, Summary, IOO, MC servo analysis OLTFs.pdfCLTFs.pdfmcLoopAug8.zip
             Reply  Fri Aug 8 18:08:12 2014, Koji, Summary, IOO, MC servo analysis 
             Reply  Sat Aug 9 14:35:28 2014, Koji, Summary, IOO, MC servo analysis MC_OLTF_Fit.pdfliso.zipMC_CLTF_Fit.pdfMC_CLTF_new.pdfMC_OLTF_new.pdf
Message ID: 10354     Entry time: Fri Aug 8 15:57:29 2014     In reply to: 10351     Reply to this: 10356     10359
Author: ericq 
Type: Summary 
Category: IOO 
Subject: MC servo analysis 

 I did some further measurements, to try and see what corresponds to what. In the end I performed four measurements:

  1. Closed loop gain measurement on SR785: Source to MC exc, T'd to channel one. Test 2 to channel two.
  2. Open loop gain measurement on SR785: Source to MCexc, Test 2 to channel one, Test 1 to channel two.
  3. Closed loop gain measurement on AG4395: RF Source to MC exc, T'd to R input. Test 2 to A input.
  4. Open loop gain measurement on AG4395: RF Source to MC exc, Test 2 to R input. Test 1 to A input.

I then converted OLGs to CLG and vice-versa with CLG = 1/(1-OLG)

Here are two plots showing the measured and inferred loop TFs for both closed and open. 

OLTFs.pdfCLTFs.pdf

The best agreement seems to be between the directly measured OLGs. Maybe I did something weird with the CLG measurements, or input impedances are distorting things ... 

All data is attached, along with code used to generate the plots. 

Attachment 3: mcLoopAug8.zip  246 kB
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