[evlatests] Modcomp-Free Tests, 18 May

[Ken Sowinski]

On Sun, 20 May 2007, Rick Perley wrote:

>    We are seeing many 'short drops' on ALL antennas.  In all cases,
> these affect all four IFs simultaneously and identically.  These were
> much worse during the 'Modcomp-on' data.

Is this the same as what you used to call the "short, shallow
drops"?  If it is really seen with the Modcomps too, then I will
have to start thinking about ways to make it in the correlator.
If it is really true that we continued to see it with phase
switching off then explanations are hard to come by.

>       EVLA antenna 18D is showing multiple amplitude levels, which have
> large phase changes as well.  The effect is unlike any of the
> multiple-level problems I've reported before.

This is likely the VLA sampler forgetting how to do delay.