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Entry  Thu Feb 10 01:16:42 2011, Tara, Notes, BEAT, collection of beat data, H1 arm noise, and SR560 noise  beat_2011_02_09.pngbeat_data.matcode_2011_02_09.m
    Reply  Thu Feb 10 12:00:55 2011, rana, Notes, BEAT, collection of beat data, H1 arm noise, and SR560 noise  Screen_shot_2011-02-10_at_10.39.43_AM.png
Message ID: 487     Entry time: Thu Feb 10 01:16:42 2011     Reply to this: 488
Author: Tara 
Type: Notes 
Category: BEAT 
Subject: collection of beat data, H1 arm noise, and SR560 noise  

I plot beat noise PSD, with estimated H1 arm noise, and SR560 noise converted to frequency noise in the current beat measurement. From the approximation, SR560 noise will be smaller than H1 noise.

 

 The conversion for SR560 noise to frequency noise is computed by finding the slope of signal from self beat measurement.

parameters are from Frank's entry below

amplified (DC-coupled) signal from mixer using SR560, LP@30Hz, gain20 in channel C3:PSL-GEN_DAQ15

185.0MHz :  -2.405V
154.2MHz :   0.005V
123.2MHz :   2.263V

 

The pkpk values is then (2.263V - -2.405V)/gain20 = 0.2334 V over 185 MHz - 123.2 MHz = 61.8 MHz range.

Thus the signal is = (0.2334V)/2 sin ( pi df/ 61.8 MHz)

This gives the maximum slope = 0.2334 V* pi /2 /61.8 MHz, or  ~ 170 MHz/V.

SR560 noise is estimated to be flat, 5nV, at high f, a corner at 10Hz which gives 5 uV at 10mHz.

multiplied by 17 MHz/V to get frequency noise from SR560.

 

 

Attachment 1: beat_2011_02_09.png  58 kB  | Hide | Hide all
beat_2011_02_09.png
Attachment 2: beat_data.mat  209 kB
Attachment 3: code_2011_02_09.m  819 Bytes  | Hide | Hide all
load beat_data.mat

%beat_pll_100kHz(:,3)=beat_pll_100kHz(:,2).*sqrt(1+(0.16./beat_pll_100kHz(:,1)).^2);

% correction for 160mHz high pass (AC couple)
beat_pll_100kHz_2(:,3)=beat_pll_100kHz_2(:,2).*sqrt(1+(0.16./beat_pll_100kHz_2(:,1)).^2);
beat1_2011_01_30(:,3)=beat1_2011_01_30(:,2).*sqrt(1+(0.16./beat1_2011_01_30(:,1)).^2);

loglog(beat1_2011_01_30(:,1),beat1_2011_01_30(:,3)*71e3... 
      ,beat2_2010_11_29(:,1),beat2_2010_11_29(:,2)*71e3,...
... 7 more lines ...
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