[evlatests] Broken/Malfunctioning Switched Power -- A summary

[Michael Rupen]

>    1) Global problem:  ea17 in LCP was providing extremely noisy data.
> The PDif values vary over a ratio of nearly 2:1 at all bands, and in
> both IFs B and D.  The same variations are seen in PSum, but they are
> proportionally much smaller -- so the derived Tsys also varies by nearly
> a factor of two.  The character of the variations is pure noise -- there
> is no trend on any timescale.


I assume this is NOT present in the visibilities?


>    2) Band-dependent problems:
>
>    a)  ea28 in LCP at L-band.  The system works well for about half the
> time.  For the other half, the values are many times higher, with
> enormous variations in power.  The system stays in each state for
> typically an hour or two, then reverts to the other state.  *** This
> situation has never changed since the switched power system was
> installed on this antenna***.

Again, I assume this is NOT present in the visibilities?


Have you played any games with applying the switched power from one
subband to another?  This might help avoid the RFI problems you
mention.  Or does out-of-band RFI affect *all* subbands equally? (which
would be surprising)

              -- Michael