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Re: Amateur radio module on commercial Geo Sat?

>One more thing Tony: Doppler shift varies between different stations and
>their position to the satellite.  For a geosynchronous bird doppler isn't a

Doppler is a significant problem in a digital satellite link only when
the data rate is low relative to the frequency uncertainty. At high
speeds, the tracking loops will simply follow it.

In any event, much of the frequency uncertainty can be removed by
having the ground stations compute it in an open-loop fashion from a
set of orbital elements, the current time, and the station location.

We wouldn't have to rely on NORAD here, either; to the extent that the
doppler- and range-vs-time profiles can be measured by our modems, we
can compute our own orbital element sets from them.


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