[amsat-bb] Re: Terrestrial QRM to FM satellites

Patrick STODDARD (WD9EWK/VA7EWK) amsat-bb at wd9ewk.net
Thu Sep 20 16:03:23 PDT 2007


> No, it's certain that it's on the uplink.  The weaker stations
> are having trouble getting in, and the signals disappear when
> the satellite pass is over.  The strength of the signal is closely
> related to movement of the satellite, and my S-meter doesn't
> change vs the satellite when the signals are there.

This is the same thing here.  In fact, on a couple of occasions, I would
call a ham friend who had also worked the same satellite passes to
confirm what I heard was something he also heard.  As you mentioned,
I would hear the other chatter and I could tell it had to be coming from
the satellite downlink and not from local simplex activity.  The foreign
chatter will usually go away as the satellites move northward, but the
other stuff has sometimes stayed on AO-27 for most of its 7-minute
passes.  The QRM would follow the Doppler shift, not stay on one
frequency regardless of the satellite's movement.

I remember a couple of weeks back clearly hearing a CW ID on an
AO-27 pass.  I think I might have that pass recorded at home, and
will try to locate that recording.  I seem to remember it was a US

We in North America don't have it as bad as our Australian and
European friends who deal with all sorts of intruders.  If the voices
are hams mistakenly using a satellite uplink as a local simplex
frequency or as part of some repeater/remote-base system, some
polite persuasion should be employed before involving the

Back to work...  73!


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