[evlatests] Persistent P-band RFI

[Frank Schinzel]

406.1-410 MHz has co-primary allocation to radio astronomy, however it 
doesn't have absolute protection due to a footnote US74.

403.5 MHz is probably some weather radiosonde.

The major ones you are noting are also very likely some meteorological 
remote sensing stations that I think are known and frequently seen.

On 1/22/24 10:14, Rick Perley via evlatests wrote:
> 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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