RE: [amsat-bb] AO40 modes

[Bob Bruninga <bruninga@xxxxxxxx>]

On Wed, 21 Mar 2001, Tony Langdon wrote:

> > I wonder if the DSP could be configured to receive a 3 Khz wideband of
> > linear PSK-31 on the uplink and then send it down in a single 
> > FM downlink? 
> 
> An FM downlink may present challenges there.  However, only one way to find
> out.  The alternative is to use a linear downlink and the pilot tone idea.
> Not as easy to tune, but would give a better S/N ratio on the ground.

Ah, but chasing 38 KHz worth of Doppler with a receiver only 30 Hz wide
would be quite a challenge...  Thats why FM down is the only viable
approach...  aw shucks, I forgot that most of our discussion has been
about a satelite PSK-31 uplink on 10m where doppler is only 600 Hz.  On
AO-40 with 2m uplink, the doppler is 5 times worse and probably a
non-starter...

bob



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