[evlatests] RFI in C-band

[Dan Mertely]

Hi Michael.  Off-hand I would think that the "narrow'
signal you saw at 6.014 GHz is just a component of
the WNMTC 6004.5 MHz Fox Mtn to Gray Hill link.  it
is centered at 6004.5, but is spec'd at 30 MHz bandwidth,
so it covers 5989.5 - 6019.5 MHz.  Previous tests with
our monitoring system showed it to be about that broad
and flat.

On the chance that there is another local narrow band
signal on top of the WNMTC broadband signal (and us!),
we'll perform additional checks.

I'm not familiar with the 5550 MHz signal--we'll ID it.

Rick also mentioned a lot of RFI below 4200 MHz.  Those
would be powerful C-band downlinks from geosynchronous
satellites  (often received in the old days with back-
yard "BUDS"-Big Ugly Dishes, even though they are actually
network feeds from LA & NY, NY to affiliate stations around
the country, including ABQ).  That downlink band ranges
from 3600 - 4200 MHz.  Mitigation?  Don't look within
+/- 15 deg of the Clark belt--strong stuff there!

Thanks for the info.

-Mert



Michael Rupen wrote:
> Our 3-bit tests last Wednesday showed 5 narrow RFI-like features in C band
> (we covered 4.976-7.024 GHz):
> 
>   5.440 GHz (narrow)
>   6.006 GHz (narrow) -- WNMTC's 6.0045 GHz
>   6.014 GHz (narrow)
>   6.240-6.270 GHz    -- WNMTC Gray Hill -> Mangus Mtn
>   6.610-6.620 GHz    -- WNMTC Gray Hill -> Smith Bagley
> 
> We had 2 MHz channels.
> 
>   Cheers,
> 
>          Michael