Satgen296  Satellite Problem No9  Interference    by GM4IHJ     25 Nov 94
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The amateur satellite frequencies of 1994 , offer a very sad picture of
failure ,on the part of the Societies which take our contributions, to
take any useful action against interference which is killing our hobby.
In the 1970s, 29MHz downlinks from Oscar 6 and 7 were completely clear of
interference. Today the situation on RS10 and RS12 on those same
frequencies is appalling. Levels of broad band noise radiating from
electronic games, radio heating equipment and cheap micro computers, is
destroying the HF band for satellite user city dwellers. Worse still, our
radio amateur organisations fail to comment on or correct the plethora of
Amateur 29MHz FM which is at its worst in periods of Sporadic E and, high
solar flux long range propagation.In particular , FM Repeaters in the
United States located right on designated satellite downlinks, destroy the
usefulness of RS10 and RS12 for long periods. Even worse , the presence of
these repeaters clearly audible at long range encourages uninformed local
FMers to join and add to the chaos. So much for international cooperation.
At 144 MHz the situation is no better. Computer broad band noise is very
loud as a consequence of Governments failure to clean up their act in this
respect. In addition several European countries seem to be totally
ignoring the wide spread use of amateur radio equipment by taxi drivers,
and fishermen. So that the presence of a 2m Icom handtalkie capable of
putting a firm uplink into a satellite , has become a regular sight
besides the tourist bus drivers seat in several Spanish speaking areas.
On 435 MHz the interference problem was slow to start. But total lack of
action by national societies when warned of the developement of major
intruders, has resulted in permanent intrusion. A very serious example of
this is the shift up in frequency of the BMEWS radars. Originally located
below the amateur band, the introduction of PAVE PAWS ( which can operate
outside the amateur frequencies ), was accompanied by a shift in frequency
so that the radar came right on top of long established satellite
frequencies. While it is appreciated that these bands are shared, this
sort of unnecessary behaviour appears to be so deliberate as to have been
either, planned or, done in complete ignorance without thought for others.
Interference from one unit of this radar is known to affect satellite
usage all the way across Northern Europe. Meanwhile , Spanish speaking
pirates, have this last year, "found" 435 MHz, and users of Amateur FM
satellites get a constant Taxi cab control broadcast whenever a satellite
is within 1500 kms of Spain.
So the overall situation in Europe is thoroughly bad. What now are we to
make of the Amsat Official who a year or two back announced that " He was
dealing with the radar problem , and the rest of us should shut up".
Equally , how does one account for the national society magazine which
censored a half page report about the radar. Needless to say neither the
Amsat Official nor the magazine have said one further word about the
subject. So no wonder things are getting worse year by year.
What can we expect for the future ? Are Radio amateur satellite user
prepared to be blotted out on all frequencies below 2400 MHz ?. Given the
performance of our national societies this is the inevitable outcome of
their dilatory approach to the matter. Without firm action these problems
will not go away - but our membership subscriptions can and already are
doing. Witness Amsat UKs loss of 500+ member recently. 73 de GM4IHJ@GB7SAN