[evlatests] Persistent P-band RFI

[Rick Perley]

There are two 64-MHz-wide bands within P-band that are relatively free 
of RFI, and are still useful for science:  288 -- 352 MHz, and 388 -- 
444 MHz.

However, within that upper band, there is a persistent, everpresent, and 
very strong source of RFI which requires a good chuck of frequency space 
to be removed.  I attach a .png file to show its characteristics -- this 
is a ten-minute long observation of the calibrator 3C48.  These data 
were taken Saturday afternoon.  The entire 8-hour run was affected about 
equally -- it never goes away.

The isolated vertical bar on the left is at 403.50 MHz.  The other major 
ones that are visible are at 407.25, 408.0, 409.5, and (weaker on tdhe 
right) 411.75 MHz.  There is plenty of evidence for pulsed emission, but 
the strongest stuff looks very constant in time.

Is there any chance this is local?  And if so, can we turn if off?

Rick
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