[evlatests] P-Band RFI

[Rick Perley]

I obtained 5.5 hours of good P-band data on Saturday morning, as part of 
the effort to sort out (finally!) the remaining polarization issues.

I have learned from long experience that, in D configuration, there is 
no sense in even trying to do astronomy in about half of this band.  I 
therefore set up the correlator to use only eight spectral windows, each 
16 MHz wide.

SPWs 01 -- 04 spanned 288 to 352 MHz.

SPWs 05 -- 08 spanned 384 to 448 MHz.

Most of these SPWs are quite clear of significant RFI, with the 
exception of SPW06, where the frequencies running from 404.5 through 
410.5 were cluttered with numerous, strong, narrow-bandwidth interference.

Other than this 6 MHz band, the only frequencies with notable problems were:

340.0 and 420.0 MHz -- a continuous 'CW-like' signal.

333, 413, and 425 MHz -- also CW-like, but not as strong as the above.

SPW08, spanning 432 to 448 MHz, had a lot of 'stuff' in it, but no 
single identifiable frequency.  The RFI was scattered, both in time and 
frequency.  Such signals are fairly easy to remove through a simple 
'clip' operation.

Does anybody know the origins of said signals?

Rick