[amsat-bb] DopplerPSK

Scott scott23192 at gmail.com
Thu Jun 13 01:23:38 UTC 2019

While it might certainly be possible to put together a solution that would
compensate your uplink so that its corresponding downlink through the
transponder holds stationary on a single spot on the downlink audio
spectrum, there are two reasons (at least) that I can think of to not go to
that trouble:

#1, the DopplerPSK app takes care of it perfectly already.  The work has
been done.

#2, if memory serves, some radios do not respond to CAT frequency
adjustments when transmitting.  In this mode, your uplink radio is
transmitting non-stop for the entire ~10 minute pass.  If you have a
hardware/software setup that can only change RF frequency when in receive
mode, that will never happen during an NO-84 pass.

Lastly, like much satellite work, the uplink and downlink are two
completely separate discussions in this mode.  While the 10m uplink works
extremely well with the DopplerPSK software and the HF radio of your
choice, receiving & demodulating the PSK31 downlink can be done by any
antenna/FM radio(or SDR), and computer combination of your liking.  Just as
one example, my setup is:

TX:  Windows PC > DopplerPSK > Signalink > FT-857d > MyAntennas EFHW-8010

RX:  70cm X-Quad > SDRPlay RSP1 > HDSDR on Windows PC (doppler track w/
Orbitron) > FLDigi

-Scott,  K4KDR


On Wed, Jun 12, 2019 at 8:20 PM k6vug at sbcglobal.net <k6vug at sbcglobal.net>

> I'm very curious about this, thanks for sharing the links.
> Looks like the program adjusts the PSK modulation within the pass band of
> the uplink, and at 10 meters, that would be relatively small.  It makes
> sense, however would this work if SatPC32 manages the uplink ?
> Secondly, I came across this on the website:
> "DopplerPSK does not provide any PSK31 demodulation; you should use a
> separate program for that purpose. DopplerPSK does not provide any
> compensation for downlink Doppler (which you would need for fully linear
> transponders)."
> Question 2 - why not use something like HRD for everything (doppler, psk,
> rotator, logging, etc) ?
> (I believe I tried it sometime back by routing of the downlink audio back
> into HRD)
> 73!
> Umesh
> k6vug
> On Wednesday, June 12, 2019, 8:10:11 AM PDT, Scott via AMSAT-BB <
> amsat-bb at amsat.org> wrote:
> I originally used the link on 2M0SQL's excellent how-to page:
> https://www.2m0sql.com/2018/10/29/using-the-no-84-psat-psk-transponder/
> ... which is:
> http://www.frontiernet.net/~aflowers/dopplerpsk/dopplerpsk.html
> If that link isn't available, you're welcome to the copy I downloaded which
> has just been put at:
> https://www.qsl.net/k/k4kdr//downloads/DopplerPSK_0.2.zip
> -Scott,  K4KDR
> ==========================
> On Wed, Jun 12, 2019 at 10:53 AM Roy Dean via AMSAT-BB <amsat-bb at amsat.org
> >
> wrote:
> > With all this talk of NO-84, and me finally having a semi-operational
> > ground station - I went looking for DopplerPSK, but every link I found
> was
> > broken.  Where can I get this software?
> >
> > --Roy
> > K3RLD

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