[amsat-bb] going digital

[JoAnne Maenpaa]

Circumstances in the launch business have driven many groups,
including AMSAT, to select the cubesat path to space. Arguing about an
on-going project isn't productive but I find discussions about future
possibilities interesting. These discussions don't have come at the
expense of the current project plan (such as why use FM when this
project is already 2 years in progress). We do have future satellites
still on the drawing board however!

On the digital radio front Phil makes a very good point ...

> So many hams seem to automatically assume, for no good reason, 
> that getting on any new digital mode must necessarily require 
> exotic, expensive and hard to find components and a PhD to use. 
> But the required hardware is now very common, and nearly all
> of the "complexity" that defines any particular digital communi-
> cation system these days is implemented almost entirely in soft-
> ware that costs nothing to copy and distribute once written.

I used free software, my FT-857, small yagis at fixed elevation on a
TV rotor to decode Delfi, ARISSat, FUNcube, and 2-way with ISS packet.
The computer that does this is a bargain e-machine box with the only
modification being additional memory.

The software tools for digital modes on these satellites were a free
download. The key to getting the software and your computer to do this
requires one additional piece of hardware if you use an external
radio. If you use one of the various flavors of Dongles on your
computer you only need to add a software audio path (another
download).

When thinking of projects to enter into the digital communication
world plan on building or buying that digital interface to connect
your radio to the soundcard. A few days or weeks spent on the
soundcard interface is the key link to enter this exciting other half
of satellite operating. 

There are many paths to soundcard digital interfaces. Google is your
friend. I bet a local dealer would love to sell you a RigBlaster
(which many have had good luck with).

I used a less expensive off-the-shelf digital interface from a place
called Donner Digital Interfaces. He sells it on the web:

http://www.donnerstore.org/ ... the page is quite an entrepreneur
operation, select digital interfaces from the menu on the left side.

http://www.youtube.com/watch?v=34dy21z2I8Y ... shows how to set up a
Donner interface to your rig. More good news ... the setup for the
digital interface is the same for HF, VHF, or UHF. Once installed you
have digital modes on all bands. (On HF I use the JT-65 software which
often decodes DX signals so weak I cannot hear them by ear - it was
just another software download.) PSK and SSTV were more downloads. But
ya gotta install that Soundcard interface to get to this good stuff!

http://www.eham.net/reviews/detail/2073 ... some reviews and
discussion to help your research.

--
73 de JoAnne K9JKM
k9jkm at amsat.org 
Editor, AMSAT Journal