[evlatests] L-band Switched Power Troubles

[Rick Perley]

    1)  Indeed, antenna 23 has no L-band receiver -- certainly explains 
the lack of switched power!

    2) Switched power in ea28, LCP, has behaved in this manner for a 
long time. 

    3) Half-amplitude fringe power is completely consistent with my 
report -- the switched power levels are fine, but the correlated power 
(which is what the fringes measure) is half of what it should be, 
presumably because the uncorrelated (i.e. receiver) noise is two times 
too high.

Ken Sowinski wrote:
> On Tue, 20 Sep 2011, Rick Perley wrote:
>
>>    Reviewing some recent data at L-band reveals:
>>
>>    Antenna 23 has zero PDif values in all IFs.
>
> No switched power at all and almost no poewr at the downconverter.
> It looks like there is no receiver in this antenna.
>
>>    Antenna 28, LCP only, has random-looking noise on the PDif -- the
>> scatter is about equal to the mean value, leading to nonsensical values
>> of Tsys.
>
> Switched power at the downconverter may have been wrong for
> LCP at the downconverter.  Interference at the time made it
> hard to be sure.
>
>>    A side note:  It appears that Tsys for antenna 7 is about twice what
>> it should be.
>
> Switched power is about right.  Maybe something else is wrong.
> Fringes are clearly too weak by half.