[amsat-bb] FM birds

Phil Karn karn at ka9q.net
Sun Jul 27 05:24:15 UTC 2014

On 07/22/2014 07:49 AM, wa4hfn at comcast.net wrote:

> SSB/CW birds are the only way to go and if you build it they will
> come  .

Think about what it would be like to tune for Doppler while working SSB
through a LEO satellite on microwave.

Before you say "computer control", work out the effect of even a tiny
error in your clock or orbital elements on a high elevation pass and
remember that SSB has no carrier or pilot tone for closed-loop frequency

Sure, you could have a second receiver track the satellite's beacon. But
if you're going to all that trouble, why not just have it track a
single high speed data stream from the satellite, one that's much less
affected by Doppler in the first place?

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