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Re: 2m FM from Geo (RAgeo)



On Thu, 24 Jul 2003, William Leijenaar wrote:

> An FM transponder in Geostationairy orbit, very interresting idea but it
> will never work.  You will have one channel for hundredthousands of
> amateurs having their big guns fixed to this geo-sat and open fire when
> it is switched on :-)

Only because all existing transponders have never been operated under net
control situation.  I think HAMS will follow the leadership of NET
control if asked.  And the uplinks will not be generally published except
to those who reserve it.

> Very interresting, but you know it would take a lot of organisation work ??

Most of that can be automated under a set of guidelines that drives the
reservation system.

> Besides that, it will only be used as "local chat transponder"...

"Local" being the whole continent.  But yes, presumably, at times the
subject of any given net may be of specific interest to only a small group
that has reserved the transponder for their "local" topic of discussion.

> And who will get the transponder when more reservations at the same time are
> done ????  May I guess ? :-)

The satellite owner/operator/reservationist will decide.

> >Why FM?  Because FM (above threshold) yields much better signal to noise
> >ratio than SSB.  And the purpose of this channel is not to "dig-out-the-
> >weak-one" but to communicate meaningful information reliably among a large
> >group of people under the guidance of a directed net.
>
> Yeah above threshold, but with the same amoung of power you would recieve a
> much better SSB signal. Don't forget earth noise and man made earth signals
> (like taxi stations in 2m ham band... who have also wipe antennas)

My idea would put the uplink in the UHF band. (Where radar is the primary
interference problem)...

> A geostationary satellite is ideal for broadcasting between
> main-ground-stations. Maybe it would be a better idea to use such a
> transponder as repeater-backbone, or even a packet-radio-intercontinal-
> back-bone....

But we also have all the free bandwidth of the internet for doing all
those kinds of backbone things.  I would not want any HAM satellite to be
wasting bandwidth carrying signals that can be better carried elsewhere.
The HAM satllite should always be for DIRECT access by the users, not for
others not involved with a satellite station.

Bob, WB4APR


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