[amsat-bb] Severe UHF Satellite inerference found!

Robert Bruninga bruninga at usna.edu
Wed Feb 3 15:47:39 UTC 2016

Our satellite ground station has been jammed for about a week with 60 dB
over pulse (spread spectrum)  Looks and sounds just like Wifi but from
below 420 to above 460 MHz.   Yestereday we built up a portable USB
receiver and attenuator and began measurements.

Went everywhere in the building and outside.  Could be heard 40 dB over
everywhere in the building.

But darned if the signal wasn’t always just a bit stronger right at the
Ground station console.

Switched from omni to a hand held beam.  Still signal seemed strongest
right at the console.  Turned off everything one by one.  No change.

Completely disconnected antenna, attenuator and cable but signal was still
S9 into the portable receiver (AOR AR5000) and good enough for sniffing.

Still strongest right on the console.

BINGO!  It was an FRS walkie talkie, not used in years, that someone had
pulled out of its charger (it was dead) and re-inserted a few days ago.  As
the dead FRS slowly attempted to charge up, somehow its processor must have
gone wild trying to power up and that was it!

Remember, nothing electronics anymore has a real OFF switch.  Just a
processor that is always ON to sense the switch.

When I pulled the radio from the charger, the noise instantly stopped and
nothing we can do can recreate that one-in-a-million condition.  And the
FRS radio is still dead.

But we can finally hear the noise floor again on the UHF band.


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