[amsat-bb] PSAT PSK31 experimental software

Robert Bruninga bruninga at usna.edu
Thu Jul 16 02:50:04 UTC 2015


Great!  This PSK31 TX-only software for PSAT PSK-31 solves three problems!
1) as a separate TX-only program, it lets everyone run FULL DUPLEX with
their existing PSK31 for receive
2) It makes your signal constant in the waterfall for You
3) and for everyone else even if they are not running anything special!

Maybe Andrew can comment on whether two separate sound cards are needed or
if it is possible to use a single sound card?

Bob, WB4aPR

-----Original Message-----
From: aflowers at frontiernet.net
Sent: Wednesday, July 15, 2015 6:41 PM
To: amsat-bb at amsat.org
Subject: [amsat-bb] PSAT PSK31 experimental software

I put together an experimental program called DopplerPSK to compensate for
the Doppler shift on the NO-84 (or NO-83) PSK31 uplink.  In essence, its a
PSK31 transmitter that is merged with an orbital propagator to cause your
transmitted signal to drift exactly opposite to uplink Doppler effect.  It
does this in a phase-continuous correction so that you don't get errors due
to discontinuous frequency adjustments from controlling a radio in discrete
steps.
In the case of PSAT and BricSat, it should cause your signal to stay at
constant frequency in the satellite's uplink receiver, and thus you should
get a stable frequency on the FM downlink as well.  In turn, this means you
should be able to use your favorite PSK31 demodulating software to copy the
downlink since the frequency drift should stay well within the AFC tolerance
of the software.
Anyway, if there are any adventurous people who are set up to give this a
go, I would be interested in seeing if it actually works.
You can find a rough quick-start guide (which contains an explanation of how
it works and what you need to get started) and the application package on
the rather minimalist page here:
http://www.frontiernet.net/~aflowers/dopplerpsk/dopplerpsk.html
It's an experiment, so be prepared for disappointment.  I am :-) Andy K0SM/2
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