[evlatests] RFI in X-band

[Dan Mertely]

Hi Rick & Vivek.  Yes, this is most probably from the airborne
weather avoidance radars on commercial aircraft.  If you see it
quite frequently, but it comes and goes and changes amplitude,
that is the likely culprit.  (There are a lot of commercial
aircraft from horizon-to-horizon at any one time, so the RFI
might appear continual but varying.  The most quiet time would
be between 4 & 6 AM local)  Also in the 9.0-9.8 GHz region
of X-band are the APG-68 flight control radars on F16s (flown locally
by the NMANG).  They would be infrequent, short-duration, and very
variable in amplitude.  -Mert

On 10/16/2019 11:37 AM, Vivek Dhawan via evlatests wrote:
> This is a known offender, almost always present. I captured a screen
> shot of it once, see attached. My guess is airborne weather radars.
> 
> RCP top, LCP bottom, 9-11GHz, peak-hold from Revnell's DTS spectral
> sampler.
> 
> On 10/16/19 11:02 AM, Rick Perley via evlatests wrote:
>> Â Â Â  I'm reducing some D-configuration X-band data, taken last 
>> November.
>>
>>     There is a curious RFI signal seen between ~9320 and 9380 MHz. 
>> It's very erratic (meaning, short time-scale), and quite broad-band. 
>> Also quite strong.
>>
>>     Any idea of where it's coming from?  All antennas seem equally 
>> affected, suggesting a distant origin.  But, given the data is from D 
>> configuration, this is a weak suggestion.
>>
>> Â Â Â  Rick
> 
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