[evlatests] "2-bit" sampler test

[Vivek Dhawan]

Here is the last measured 3-bit data, from Rick, and the latest '2-bit'
comparison from today. (ea15 was pulled off just before). The 2-bit is
a shade better.

-------- Original Message --------
Subject: [evlatests] 3-bit 22RCP all fixed, but ...
Date: Thu, 16 Sep 2010 14:56:46 -0600
From: Rick Perley <rperley at nrao.edu>
To: evlatests at aoc.nrao.edu

     The repaired sampler is back in the antenna, and the standards tests
done.  The results are exactly as expected:

Here's the 'noise matrix', 3bit, from Rick, RR upper right, LL lower left.

         12        15       22       28
--------------------------------------
12  |   X       .22      .22     .24
15  |  .17       X       .18     .18
22  |  .17      .16        X     .19
28  |  .17      .17      .17       X
--------------------------------------


2bit, today (ea15 removed)

         12       15      22      28
--------------------------------------
12  |   X        X      .21     .23
15  |   X        X       X       X
22  |  .16       X       X      .16
28  |  .16       X      .15      X
--------------------------------------

Ken Sowinski wrote:
> I rand the usual test program that alternates ons and offs at
> 3c286 with the T304 gain set to what would be appropriate to
> drive a 2-bit sampler.  Requantizer gains were set to the optimal
> RMS of 2.7 for four bit correlation.  I expect that the sampler
> RMS needed is about 1.0.
> 
> Ken
> 
> 
> 
> The name was C2tuned_006
> 
> 1922 UT  Started script
> 1927     Requantizer gains all set
> 1956     Stopped script
> 
> 
> I recorded the T304 output power and sampler RMS
> 
>          IFA           IFC
> ea12  -35.0/0.83   -33.9/1.03
> ea22  -34.2/1.13   -33.3/1.19
> ea28  -33.5/1.03   -34.1/1.16
>