[amsat-bb] RE: Pirate problem on FM satellites, minor problem

[Tony Langdon <tlangdon@xxxxxxxxxxxxxxxxxx>]

> The pirate stations randomly heard on FM and SSB satellites
> are usually just people operating simplex FM mobile radios
> in the satellite uplink part of the band.

Had a few of those.  Local hams who are heard on the uplink are contacted
and informed of the problem, upon which time, they usually apologise for
their mistake and and QSY.

> These stations are a combination of legimate licensed
> radio operators and some illegal operators and taxi operations.
> The legal operators are just not following the suggested
> gentleman's agreements and in those cases when they discover
> their error they will usually comply.

Indeed, it's a rare legal station who won't QSO, once the situation has been
explained to them in a reasonable manner.

> The illegal stations are only a minor problem for satellites for the
> following reasons.
> 
> 1.  Satellite uplink usually requires a significant uplink ERP for 
> proper operations (FM and SSB).  The Illegal stations or pirates

Hmm, this is not quite correct for the FM birds.  UO-14 requires 0.25W into
a 5/8 antenna to get a reasonable signal for elevations over 15-20 degrees,
and 2W into the same 5/8 for elevations over 5 degrees.  25W into a typical
base station collinear will hit the bird pretty hard, pracctically down to
the horizon.  

Yes, I have done QRP tests on UO-14, and regularly operate QRP portable.

> are usually a mobile FM transceiver, running 50 watts or less into
> a mobile antenna with a gain of 0 dbd or less (typical ERP 25-20
> watts).  

Which will put a respectable signal into UO-14.

> A satellite station with a directional antenna will easily over power
> the weak pirate mobile signals on most occasions.

Still takes a bit of power.  It's not a case of a "weak pirate station", but
massed stations, many of them quite strong, which basically precludes QRP
operation from about a minute after the first stations get into the
footprint of the bird.

> 2.  Orbit path:
> The orbit path, foot print and speed of the satellite will 
> usually take
> the satellite quickly
> into and out of the pirate area quickly.  If u do hear a 
> pirate station,
> his
> mobile radio will quickly fade in a minute or two.  If you 

Again, not with massed pirate stations.  Passes over Western Australia are
typically affected for over 5 minutes, when seen from Melbourne.  For
ascending passes, it is the last 5+ minutes that's affected, for descending
passes, the first 5+ mins. 

> have a AZ/EL
> gain
> antenna system, again your signal should usually over power the random
> pirate stations.

And a truckload of power...

> How can you compensate for pirate QRM.
> Simple, install the biggest az/el antennas system you can afford.
> And have plenty of reserve capacity for the satellites you plan on
> using.
> As always, only use the minimum power required for the desired
> communications
> and follow the suggested ERP uplink ratings for that specific 
> satellite.

If you want to forget QRP portable operation, or keep satellites to those
who can put up huge antenna arrays (that would upset the landlady just a
tad! :)  She's been pretty good, but there are limits ;) ).

Any other VKs, or people to the north want to comment on the situation in
this area?

My main point.  It's a significant problem because communications are
completely disrupted everytime the bird passes to the north-west of
Australia, not merely a minor annoyance that can be dealt with by a little
bit of antenna gain.
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