[evlatests] New (?) X-band RFI

[rperley]

I'll get you this in a few moments ...

On 2021-01-26 15:26, Steven Myers via evlatests wrote:
> If GEO, array pointing will have moved ~2deg in 10min. Would need to
> know the LST and/or AZ/EL of event to identify satellite.
> 
>> On Jan 26, 2021, at 9:29 AM, rperley via evlatests 
>> <evlatests at listmgr.nrao.edu> wrote:
>> 
>> Dan, et al.:
>> 
>> Looking at more data, it's clear the RFI is from a rapidly moving 
>> object.  The duration of the RFI is only 10 minutes or so, after 
>> which, all appears close to normal.
>> 
>> Another thing I noted:  The same RFI is seen at a higher frequency -- 
>> 11.46 to 11.82 GHz.  It's clear that these signals are also broadband, 
>> and 'blocked' in frequency in a similar manner to that reported 
>> earlier, between 10.95 and 11.19 GHz.  The time correlation is exact 
>> -- all of these rise and fall in precisely the same way.  They must 
>> have the same origin.
>> 
>> Curiously, the frequency span from 11.19 to 11.46 is completely clean.
>> 
>> Rick
>> 
>> On 2021-01-26 11:19, Mert wrote:
>>> Hi Rick.  There is a passive-only band between 10.680 and 10.700 GHz, 
>>> but
>>> 10.7-12.7 GHz is all fixed microwave (terrestrial point-to-point) and
>>> space-to-earth satellite transmissions.  We (RA) do have some 
>>> footnoted
>>> protections there, but only to the extent that their transmissions 
>>> might
>>> affect the 10.680 and 10.700 GHz band.  Those are the "hooks" that 
>>> Harvey
>>> Liszt has been using to try to prevent RFI from the new SpaceX 
>>> StarLink
>>> broadband internet service from being too disruptive to RA.
>>> I know that there are some fixed microwave systems in the area in the 
>>> "11
>>> GHz band", but I'd have to check on the exact frequencies.  Otherwise 
>>> I'd
>>> say that you are seeing standard GSO satellite transponders.  
>>> (StarLink is
>>> non-GSO, so we could only be sure of a StarLink detection if we see 
>>> the
>>> source away from Dec 0.  GSO downlinks have been in the 10.7-12.7 GHz
>>> band, like, forever.  30-40 MHz bandwidth per transponder channel 
>>> sounds
>>> likely.)  -Mert
>>>> In a recent run, some strong RFI, seen only short spacings only (due 
>>>> to
>>> fringe-winding and A config) was seen between:
>>>> 10.950 and 11.190 GHz.
>>>> The spectral characteristics show these to be in 6 spectral 
>>>> 'chunks',
>>> each 40 MHz wide.
>>>> The RFI was not seen on the (northern) calibrator, but was obvious 
>>>> on
>>> the target source, located at Dec = -5.5  So, likely a geostationary
>>> satellite.
>>>> @Dan:  Any idea what's responsible?
>>>> Rick
>>>> _______________________________________________
>>>> evlatests mailing list
>>>> evlatests at listmgr.nrao.edu
>>>> https://listmgr.nrao.edu/mailman/listinfo/evlatests
>> 
>> _______________________________________________
>> evlatests mailing list
>> evlatests at listmgr.nrao.edu
>> https://listmgr.nrao.edu/mailman/listinfo/evlatests
> 
> 
> _______________________________________________
> evlatests mailing list
> evlatests at listmgr.nrao.edu
> https://listmgr.nrao.edu/mailman/listinfo/evlatests