[evlatests] New (?) X-band RFI

[Mert]

Well Rick, if it was truly rapidly moving, it does sound more like a LEO
than a GSO satellite.  That would increase the possibility that you
managed to get a first VLA confirmed detection of a SpaceX StarLink LEO
satellite (which just so happened to be conveniently camouflaged at that
moment in front of the Clark belt).  -Mert


> 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
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