[evlatests] Strong or Pulsed RFI in X-band

[Dan Mertely]

Certainly 10.7-12.7 GHz is assigned to Fixed Satellite, space
to earth.  The strongest signals in that band, however, should
have been at the top end (12.2-12.7 GHz), which is the direct
broadcast band (DirecTV, EchoStar (TheDish), etc.).

The earth-resource satellite TerraSAR-X transmits a radar signal
at 9650/295 MHz with an EIRP of +106 dBm from 515 Km, so that is
quite likely what you saw.  It is a pulsed radar, so it should be
expected to produce a comb of spectral lines, separated by 1/pri.
We studied this back in 2012, worried about the possibility of
X-band FE damage if there was a beam-on-beam hit. (Highly, highly
unlikely.)

-Mert


On 8/8/2014 4:44 PM, Rick Perley wrote:
>      My Hydra A, D-configuration X-band data shows some interesting RFI.
>
>      1) All frequencies above 11454 MHz (to 12000) are completely obliterated by
> wideband RFI.  This is clearly a geostationary set of satellites -- the 3C286
> calibration data are only slightly affected, while all of Hydra A (dec -12, and
> the calibrator, dec -14) are wiped out.   These satellites must be VERY strong,
> as we are quite a distance (in beamwidths) from the center of the satellite belt
> (dec -5).
>
>      2) A curious (but not strong) comb of RFI showed up in one scan, lasting
> about 15 minutes.  There are six 'lines', located at 9550, 9610, 9770, 9830,
> 9890 and 9950 MHz.
>
>      3) There is a long-runnning, pulsed pair of signals at 9368 MHz. The pair
> are separated by 6 seconds, and the pulse period is about 33 seconds.
>
>      4) Weak RFI is at 9338 MHz.
>
>      All else between 8 and 12 GHz looks very clean.
>
>
> _______________________________________________
> evlatests mailing list
> evlatests at listmgr.nrao.edu
> https://listmgr.nrao.edu/mailman/listinfo/evlatests