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Entry  Wed Oct 30 00:02:25 2013, Jenne, Update, LSC, LSC demod boards need some thought 
    Reply  Wed Oct 30 01:22:56 2013, Jenne, Update, LSC, REFL 165 demod phase adjusted 
       Reply  Wed Oct 30 01:44:13 2013, Jenne, Update, LSC, MICH and PRCL gains adjusted (Config file saved) 
          Reply  Wed Oct 30 03:36:51 2013, Jenne, Update, LSC, MICH and PRCL UGFs change with ALS enabled 
             Reply  Mon Nov 4 15:46:17 2013, Jenne, Update, LSC, Thoughts and Conclusions from last week's PRMI+2arms attempt 12x
                Reply  Tue Nov 5 19:39:27 2013, Jenne, Update, LSC, OpLev time series OpLevs_during_PRMI_2arms.pdf
    Reply  Wed Oct 30 03:33:17 2013, Rana, Update, LSC, LSC demod boards need some thought 0309.png
       Reply  Wed Oct 30 08:32:55 2013, Evan, HowTo, Computer Scripts / Programs, matplotlibrc 
Message ID: 9316     Entry time: Wed Oct 30 03:33:17 2013     In reply to: 9312     Reply to this: 9318
Author: Rana 
Type: Update 
Category: LSC 
Subject: LSC demod boards need some thought 

 

 0309.png

I worked on the script SPAG4395A.py tonight with Masayuki's help. This sets up the parameters on the Agilent 4395A and then acquires the spectrum data. It had a couple of bugs before: no matter what channel you requested, you always got channel R. It also would disobey any requests to reduce the attenuation and left the Auto Atten ON. The version now in the SVN allows you to choose the channel and the attenuation.

It then makes this plot using matplotlib. The attached image is from the REFL165 pickoff at a time tonight when the arm powers were ~5-10. I have converted the spectrum from RF electrical Watts into Volts (V = 50*sqrt(W)). To go from the analyzer input to the demod board input we should scale this spectrum by a factor of ~15 (to account for the 20 dB from the coupler and the 3 dB of the splitter and a little more for losses). On the oscilloscope we see Vpp ~5 mV, so that's ~75 mVpp at the output of the BBPD which we're using for REFL165. Perhaps we can handle another factor of ~2-3 ? I'm not sure what we have in terms of linearity measurements on this thing.

EDIT: Evan is right, its V = sqrt(50*W), not V = 50*sqrt(W). ignore y-axis above

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