Re: [amsat-bb] Geosynchronous Satellites

[Phil Karn <karn@xxxxxxxx>]

>However, most base stations in the cellular industry now use multi-carrier
>linear amplifiers even though they are amplifying FM signals.  They have to
>be linear because you are amplifying more than one signal at a time and
>intermods would result from a non-linear design.  Even your precious CDMA
>needs highly linear amplifiers.

Correct. DC power is cheap on the ground, so the low efficiency is not
a big deal. Not true on a satellite. This is precisely why I think we
should consider saturating transponders and TDMA for amateur satellite
use. Techniques like HELAPS can make a linear transponder with
improved efficiency, but it's complex and is inherently limited in
bandwidth.

Phil


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