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Entry  Fri Feb 14 02:09:55 2014, ericq, Update, Electronics, Transmon QPD whitening qpdWhitening.pdf
    Reply  Mon Feb 17 20:35:19 2014, ericq, Update, Electronics, Transmon QPD whitening qpdY2whit.pdfETMY_QPD_whitening.zip
       Reply  Tue Jul 8 22:53:02 2014, Jenne, Rana, Update, Electronics, Transmon QPD / whitening 
Message ID: 9642     Entry time: Mon Feb 17 20:35:19 2014     In reply to: 9637     Reply to this: 10157
Author: ericq 
Type: Update 
Category: Electronics 
Subject: Transmon QPD whitening 

My apologies for all of that crap I left at the Y-end... I cleaned the rest of it up today. 

I took transfer functions of the four ETMY QPD whitening channels today. (Attempted the ETMX ones too, but had troubles driving the board; detailed below). I've attached a zip with the DTT xml files for the cases of no whitening / 1 whitening stage / both whitening stages engaged. Here's a plot of both whitening stages engaged. 

qpdY2whit.pdf

 

Given the way I measured, the DAC output anti-imaging is in the TFs as well. ( This is a D000186 board; with something like a 4th order elliptic LP, but I need to look at the board / fit the TF to see the parameters, there are different revisions with different filter shapes.) 

The c1scy model had excitation blocks on some of the unused DAC channels (C1:SCY-XXX_CHAN9 etc.), but these were in the second DAC output connection, and not cabled up. However, the 8th channel on the DAC had no connection in the simulink model, so I added another excitation block there (C1:SCY-XXX_CHAN8), and used the anti-imaging front panel lemo connector to drive the input of the whitening board. 

I also added a similar channel to the SCX model, but no data would show up in the channel as viewed by data viewer (though the channel name was black), or in analog world. There's the additional weirdness that the SCY excitation channels show up under SCX in DTT and awggui... I'm not entirely sure what's going on here.

I still need to look at the noise, and peek inside the boards, to check for homemade modifications and see if there are bad things like thick film resistors that may be spoiling the noise performance...

Attachment 2: ETMY_QPD_whitening.zip  5.104 MB
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