[amsat-bb] Re: Allocations in L-band

Alan WA4SCA at GMAIL.COM
Tue Nov 20 05:26:16 PST 2012


Someone years ago told me that one of the early amateur satellites had a
mode-L beacon, but because the rules changed, it was never turned on.  I
haven't been able to verify or disprove this story.

Alan
WA4SCA
 

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Trevor .
Sent: Tuesday, November 20, 2012 4:10 AM
To: amsat-bb at amsat.org
Subject: [amsat-bb] Re: Allocations in L-band

--- On Mon, 19/11/12, Richard Ferryman <g4bbh at btinternet.com> wrote:
> Just curious - Can someone enlighten me as to why there is no allocation 
> for satellite downlinks in L-band (at least in the bandplans I have seen).
> There are uplinks around 1267 to 1269 MHz. Is it due to possibility of 
> interference with commercial/military/aeronautical systems?

I believe it dates back to a WARC conference in about 1971. Prior to that
the Amateur Service had I believe been able to use any Amateur Frequencies
just as they can still do for that other form of Space Communication - Moon
Bounce (EME).

Wayne Green W2NSD does make references to the loss of satellite frequencies
a few times in his column in 73 Magazine from that era, see 73 Mag archive
at http://archive.org/search.php?query=73%20magazine 

Although a separate service, the Amateur-satellite Service, was created they
were only given access a limited sub-set of the Amateur Service frequencies.
For the UHF and Microwave bands the satellite segments were all remote from
the terrestrial weak-signal segment meaning separate equipment had to be
built to work satellites. Back in those days even 435 MHz would have seemed
"remote" from the 432 MHz weak-signal area due to the use of 28 to 432 MHz
transvertors that only covered a narrow 2 MHz segment of the band. We share
432-438 MHz with commercial SAR satellites but why in the 70's we weren't
allowed to use the whole of 432-438 I do not know. Maybe no-one thought to
ask for the whole segment ?

The same with 1260-1270, why it's there I don't know perhaps someone can
enlighten us. The band 1260-1300 MHz is used for wideband Global Positioning
transmissions from Galileo, see 
http://www.southgatearc.org/articles/galileo.htm

Do restrictions that were applied to the Amateur-satellite Service 40 years
ago (but not to Moonbounce) still have any relevance today ? again I don't
know. 

Ideally the Amateur-satellite Service should have access to the weak-signal
segments of all the UHF and Microwave bands for both Earth-to-Space and
Space-to-Earth so we would only need to build one set of equipment on each
band for both terrestrial and satellite working. It would be good if IARU
were to work towards that objective.

73 Trevor M5AKA


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