[evlatests] More on noise for mode 'PA'

[Bryan Butler]

as ken said in the coordination meeting this morning, the key date will 
be september 2006 - the point at which the new correlator controller was 
turned on for all observations.

gustaaf & mark - did we not check polarization when we were testing the 
new controller?  i had it in my head that we did, but may be mistaken.

	-bryan


George Moellenbrock wrote:
> 
>> I then remembered that I had taken data in mode 'PA' for observations of
>> 3C273, back in 1997, with the same BW (12.5 MHz) as the recent tests.  I
>> have loaded these data, and did a quick calibration.  The result of this
>> is that there is *no* difference in the noise, as shown by the histrogram
>> distributions in real and imaginary parts, of the four correlations.
>>
>> Thus, it appears that this problem is a relatively recent development.
>>
> 
> Among the most recent of my mode 'PA' instr pol stability and freq-dep 
> tests was an observation in Mar 2006.  In that observation (15ch, L-band), 
> the noise in the cross hands and parallel hands appears to be the same (I 
> am examining the calibrated data).  So I concur with Rick that the problem 
> is a "relatively recent" development (though my definition of "relatively" 
> is a little different than his...), i.e., the problem was introduced AFTER 
> Mar 2006.
> 
> -George
> 
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