[amsat-bb] Two way SSTV exchanges using PSAT2

[Robert Bruninga]

I dont think that will work.  There has to be a tone, say 400 Hz that is
then AM modulated at 3.25 Hz.  The 400 Hz or so lets it get through your
transmitter audio circuits, and then the 31.25 Hz AM modulation of that
tone is what looks like PSK31 carrier.

Both PSAT and PSAT2 both have an audio PSK31 telemetry down around 300 Hz
(I need to look them up) so we need to avoid those areas so as not to
interfere with telemetry.  And not go above say 500 to avoid being in the
area where the SSTV tones are.

Bob
WB4APR

On Fri, May 15, 2020 at 4:27 PM Pedro Converso <pconver at gmail.com> wrote:

> Nice Idea, worth to be tried, as alternative:
>
> Use online generator setted to 31.25 Hz that can be adjusting volume using:
>
> http://onlinetonegenerator.com/
>
> 73, lu7abf, Pedro
>
> On 5/15/20, Robert Bruninga via AMSAT-BB <amsat-bb at amsat.org> wrote:
> > As soon as we see a report that 2-way SSTV through PSAT2 actually works,
> > then we can solicit the popular SSTV Authors to add the 31.25 Hz optional
> > modulation that will automatically bring up the SSTV (PSK31 actually)
> > transponder.
> >
> > Will this be the first practical SSTV transponder?  I know SSTV 2-way has
> > been done before, but with the Very low Doppler shift on the 10m uplink
> > and the no-tone Doppler on the FM downlink, this should be pretty
> straight
> > forward...  And it does not compete with the high demand that prohibits
> > SSTV via other popular satellites.
> >
> > Who will be first? (I updated these comments on the
> > http://aprs.org/psat2.html page).
> >
> > And remember, you can do this on the identical HF/UHF PSK31 transponder
> on
> > PSAT too.  That's two satellites supporting this mode.
> >
> > And if still people don't use PSAT and PSAT2, for PSK31 or SSTV, then I
> > guess we could even open up the 10m uplink on PSAT2 to voice contacts!
> > (Cannot do this on PSAT since its uplink (28.120) is not in a voice
> > segment.
> >
> > Bob, WB4APR
> >
> > -----Original Message-----
> > From: Brian Wilkins KO4AQF via AMSAT-BB
> > Subject: Re: [amsat-bb] Two way SSTV exchanges using PSAT2
> >
> > Concur, I use CQ SSTV on iPhone. Works great! I have also used MMSTV on
> > Windows laptop. Worst case, record it, clean up audio in Audacity and
> play
> > it back with one of those apps listening.
> >
> > On Fri, Andrew Glasbrenner via AMSAT-wrote:
> >
> >> Until I figured out a problem I was having, I used SSTV by Black Cat
> >> Systems on my Iphone in the shack. I just put the phone in a headphone
> >> cup on the desk and away we went.
> >>
> >> 73, Drew KO4MA
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>