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Re: Satellite communications from hand helds



On Sun, 26 May 2002, Michael Hart wrote:

> Last night I saw a show about the US ECHELON network.  They indicated that
> the satellites used could receive signals from mobile telephones.
>
> What are the main technical problems in designing a satellite to enable hand
> held FM communications via satellite?
>
> Are these difficulties able to be overcome in the short term?

UO14, AO27, PCSAT, ISS all work just fine with handhelds.  The problem is
QRM since they all support only a single channel.  In that sense, then
the only technical problem is BANDWIDTH.  But as you increase BANDWIDTH,
then you must increase POWER.  To increase POWER you must have a bigger
satelltie solar panels etc...

That kind of brute force approach with FM is not the best way to get
where you want to go.  DIgital techniques with optinum multiplexing
tchniques are probably the answer...

Bob


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