[evlatests] Bad Correlator Behavior, last Saturday

[Paul Demorest]

Rick,

I could take a look, do you have a specific example of a bad ant/spw/scan? 
Also what does this mean:

> Furthermore, correlation between apparently 'dead' antennas give correct
> results.

I briefly checked the online cal solutions for your project and didn't see
anything obviously wrong (aside from one spw near 408 MHz that I think you
already noted for bad RFI).

-Paul

> I had an 8-hour test run Saturday afternoon and evening, at P-band.  I
> set up the correlator to cover just 8 SPWs, spanning the mostly
> RFI-clear areas.  Each SPW was 16 MHz wide, covered with 125 kHz
> resolution.
>
> The lower half came through just fine.  No problem noted.
>
> Not so in the upper half (384 -- 448 MHz).  For about two hours in the
> middle of the observation, many antennas and SPWs gave zero signal.  I
> know this is not an antenna problem, because the distribution of the
> 'dead' antennas was different for each scan and polarization.
> Furthermore, correlation between apparently 'dead' antennas give correct
> results.
>
> It is extremely difficult to flag out these apparently dead channels --
> I'll likely have to abandon this half of the data (which is a pity, as
> the upper frequencies are where the moon is strongest).
>
> The project code is TLOW0002, in case somebody wants to look into what
> went wrong.  IAT times were 0/22:35 to 1/06:40.  The 'bad times' started
> right about at 1:00:00, and last for about 2 hours.
>
> Rick
>
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