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Re: DSP based High Speed Data



Ken Tentarelli <ken@sugar-river.net> wrote:

> > > We need to make DSP easier for Hams to tinker with.  Every
> > > ham, who wants
> > > to, should be able to afford a DSP system that is fiddle friendly.
>
>Yes,  that's the essence.   Look at how popular the Basic Stamp has
>become among hobbyists.  Someone needs to come out with a Basic
>interpreter for a DSP --   and a library of modules like the ones Intel
>has for the Pentium.

Basic? Say what?

DSP is all about brute MIPS number crunching. A Basic interpreter
would be a colossal waste of time and money.

One of the better environments for DSP hacking is still a PC
with a sound card. You get useful OS support, development
tools, and it tracks satellites too. If you're reading
this message you have a PC, or access to one. Have you
priced sound cards lately? The last one I bought cost me
less than $CDN 20.00. It does packet, SSTV, PSK31, weather
satellites, and plays MP3s too. What's *your* excuse?

If you don't like the present state of DSP development tools,
start writing. Don't ask me: I'm not volunteering. I have my
own axes to grind. :-)

One issue that was raised earlier (Hi Ulf!) was the tradeoff
between analogue and digital data demodulation. At the current
amateur state of the art we have 9600 baud easily handled
in sound cards and DS eval board. The next step up for amateur
satellites is P3D's 153.6 kbps downlink, which is far beyond
the capability of any DSP I can afford. The obvious - and
completely appropriate - solution is a hardware modem, with
the HDLC stream processed by software.

A useful collection of articles is at:

   http://www.ife.ee.ethz.ch/~sailer/ham/ham.html

This is the same Thomas Sailer who wrote the soundmodem support
for flexNet and Linux. His DSP Modems paper is a particularly
good summary of what's involved.

Laura Halliday VE7LDH     "Que les nuages soient notre
Grid: CN89mg               pied a terre..."
                                   - Hospital/Shafte

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