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Re: CQ PSK31 on Oscar 10



Hi again,

I can only agree with all what Stacey says.

"Stacey E. Mills, M.D." wrote:

> Remember, both AO-10 and AO-13 had PSK beacons (at 400 baud).  If it's good
> enough for the beacon, it's good enough for the passband :-).  We have
> allowed and encouraged SSTV through the sats for years with similar
> reasoning. The ranging measurements that the P3D group have been obtaining
> on AO-10 are made through the transponder with 400 baud PSK signals without
> difficulty.

This reminds me on the first 400 Bit/s PSK Packet Radio QSO via
OSCAR-10, almost 15 years ago!

As Stacey pointed out, the P3 command stations are already using PSK for 
a long time and for a very good reason.

In late 1984 I've got my first TAPR TNC-1 and used it terrestrial. Some 
people even tried to use it with it's build-in 1200 baud AFSK modem over 
Satellite in SSB. Indeed with very poor performance and too much power 
was needed.

P3 command stations already knew how nicely 400 Bit/s PSK works, even 
on a linear transponder.  Very little power with signals much less 
than the beacon could be used for an error free communication.

At that time we mostly used the ATARI 800 groundstation hardware and 
software designed by Karl Meinzer, DJ4ZC. He designed the 400 Bit/s PSK 
communication system for the first AMSAT P3-A satellite to allow 
communication with the computer even under very bad circumstances and 
with very weak signals.

After I got my TNC-1, I thought why not trying to use 400 Bit/s PSK with 
the TNC-1?

The TNC-1 already had an "Modem Disconnect" connector for an external 
modem. It was to easy and after a few days I already had a complete 
hardware design ready for testing.  The modulator was very simple, 
using only very few components. For the demodulator I used the 400 Bit/s 
demodulator which was already in use for my P3 command station.

Testing via OSCAR-10 gave excellent results, as expected.

Soon our canadian command station Randy Smith, VE1SAT/VE6 in Alberta
also modified his TNC-1 for 400 Bit/s and on the 29th December 1985 
we made our first QSO in 400 Bit/s PSK (AX.25) over OSCAR-10. He also 
used his other callsign, VE1PAC.

We made a couple of regular contacts this way and we had a lot of fun.
But unfortunately we were the only ones. Not much interest by others,
I guess we were a couple of years to early with this idea..  ;)

Well, that's long time ago...hi

With PSK31 and the soundcard, it should be even much easier now. 
I personally would encourage any use of these PSK modes on linear 
satellite transponders.

Best 73s de Peter DB2OS

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