[evlatests] spectral line tests

[Ken Sowinski]

On Wed, 25 Jul 2007, Ken Sowinski wrote:

> On Wed, 25 Jul 2007, Gustaaf van Moorsel wrote:
>
>> In IF 1, LL, the line is detected only on VLA - VLA and EVLA - EVLA
>> baselines, both at the same location.  On mixed baselines the cross
>> correlation spectrum looks like it is caused by a frequency mismatch
>> between VLA and EVLA.
>> 
>> In IF 1, RR, the line is displaced on the VLA - VLA baseline by what
>> looks like a quarter of the total bandwidth.  Not surprisingly, no
>> correlated signal was found on mixed baselines.
>
> It looks like the IF A Fluke did not respond to (at least) the
> high order part of the command for this scan and remained at its
> setting from the previous scan.  This accounts for the shift
> of ~1.5 MHz in IF A and the loss of correlation in IF C because
> the 350 MHz PLL is out of lock.

This happened a week ago and seems to be what Rick complained
about an email or two ago.  It was IF A in both cases.  It is
hard to know whether to start chasing command timing, CMP, or
Fluke.