[amsat-bb] Re: Digital modes with a handheld

[Bruce Robertson]

On Wed, Jul 23, 2008 at 3:17 PM, Allen Vinegar <tokens at myranch.com> wrote:
> There are several good howto tutorials to help people get started on the FM birds with a handheld. How about one for digital mode using a Kenwood TH-D7AG? Or is it not practical to attempt digital mode with a handheld? I am new to the satellites and have much to learn.
>
> Thanks for any help you all can provide.
>
> 73, Al, W8KHP

Al, that's a good question. I have found the AMSAT digital satellites
guide to be a very good read, though I don't think it provides exactly
what you want.

In lieu of a guide like you describe, I would recommend that you use
the FM guide to understand the tuning and reception issues and, at the
same time, experiment with similar terrestrial digital modes.If you
have a TH-D7AG, then start with APRS, since there is certain to be
traffic on that mode in your area, and it's really easy to see when
the ht is receiving data. Then combine the two skills to receive a
bird that is running APRS.

A more advanced skill is to use the tnc inside the Kenwood to talk to
a program on your laptop. Again, test that this is working
terrestrially first. Use 1200 bps at first, and test it using local
APRS signals and a terminal program on your computer. There are lots
of cubesats, etc that run this mode many of these projects provide
programs that decode their telemetry. When this is working, go up to
9600 baud and download from GO-32 and AO-51's telemetry.

If you can get your hands on a SSB radio, like a FT-817, give Delfi C3
a shot. Its software does soundcard demodulation of the telemetry
*and* provides a graphical display of the meaning of the telemetry
*and* uploads your frames to the folks in the Netherlands.
Flat-out-cool, and it sounds like pretty soon we won't be able to play
with this because the bird will become a communications satellite :-)

A severe warning, though: collecting digital information, especially
telemetry, can be quite an addicting activity. After all, the other
radio operator is on the ground, but the spacecraft's telemetry is all
about the conditions in that hostile and fearsome territory, outer
space.

73, Bruce
VE9QRP