[amsat-bb] Question about doppler correction software

Scott Wilson s.wilson at yahoo.com
Fri Aug 31 07:54:41 PDT 2007

I have a question regarding software doppler correction - in particular
when using linear satellites.

I am working on some control software that is a little more flexible than
what I've used. I really like SatPC32 on Windows and Predict/gsat on
Linux. I haven't yet fallen in love with any available software, but
that's really a different story.

I can imagine that doppler correction for an FM sat is rather easy in that
you simply tune the transmitter/receiver to the published frequencies
depending on the operating mode.

I'm a little less sure how that would work for a linear satellite. As
mentioned before, I do have a chart from AMSAT that lists channelized
frequencies for them. If I can tune the transmitter such that the
frequency at the satellite is one of the listed frequencies, how sure can
I be that the receive is as published?

Can I extend that to the point where I would be able to automatically
determine frequencies (at the satellite) of the downlink for a given
uplink and then compute doppler from there? It would then be fairly
convenient to tune within the satellite's passband and let the computer do
the 'thinking'.

Thanks for any feedback.


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