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Proposal: SDR-DSP receiver (was: Re: Cube sat and DSPs(was Re: cube sat))

Hello Hams,
This brings up a very interesting point, which I am thinking about right
now very intensely.. but I am lacking of some support and knowledge..

Remember the TAPR/Amsat DSP-93? I don't know it's shortcomings, but fact
is, it is discontinued.. I would like to so a step further and design an
all digital SDR-DSP receiver, quite similar to Moe Wheatley AE4JY and
Pieter Ibelings (N4IP), but with a small DSP behind, so you can use it
as a standalone receiver, rather than having to connect it to a PC.

Proposal is to is a 65 MSPS ADC with the digital down converter and
DSP.. so possible reception would be somwhere between 0.1 and 30 MHz.
Perhaps direct reception of the aliased image of 144 MHz (at 14 MHz)
would be possible as well.. a common problem like bad large signal
performace is negligible as we deal with sat-downlinks.. we don't have
large signals!!

What I have:

- a basic idea how this works
- some sample devices
- experience in layouting and a PCB company at hand.. :)

What I need:
- more people willing to join (!)
- some techies to iron out the bumps.. ;)
- some DSP coders.. I started digging into it but with some experience,
things like SSB, FM, AM and CW demodulation is a piece of cake..
- more ideas: this baby could also handle PSK31 or high speed PSK
decoding (anybody interested in decoding the deep-space probes?),
digital voice encoding (with forward error correction!).

I think this is a real challenge.. when keeping all open-source, this
could be a wonderful project pushing the limits !

Hpoing to trigger some discussion..

73s, Achim, DH2VA

> Date: Sun, 28 Mar 2004 19:12:17 -0900
> From: "Edward R. Cole" <al7eb@acsalaska.net>
> Subject: Re: [amsat-bb] Cube sat and DSPs (was Re: cube sat)
> At 07:27 PM 3/28/2004 -0500, Dquagliana@aol.com wrote:
>>Keith N6ORS writes:
> ***snip***
>>Now, converting the RF input down to the audio range, 
>>where the DSPx's ADC can process it, with the remaining 
>>275 milliwatts (of that 1/2 watt power budget) is left as 
>>an exercise to the reader, but should be achievable in a 
>>simple receiver.  QRP kit type receivers typically use 
>>much less than 275 milliwatts on receive.
>>In addition, there are open source applications already written
>>for the DSPx and free development tools.  If someone does launch a
>>DSP processor, factors such as free and open tools and a known
>>architecture will help to increase your pool of available DSP 
>>programmers from among the ranks of amateur radio operators.  
> ***unsnip***
> As you speak here, a fellow in the amateur radio astronomy world has built
> a  I-Q direct-conversion receiver for 1420 MHz with 98 KHz bw.  May not be
> space qualified chips but didn't I just read the the Universities were
> cobling up satellites with RS parts (or such)?  Then its the sw that does
> the demod.  Sounds like a SDR, right?  So design a standard radio and
> launch them and install whatever sw your heart desires.  Want to change
> later...upload the change.
> No I do not have this expertise...but this is a college student doing this
> if I am not mistaken.
> 73s Ed- AL7EB


     Achim Vollhardt
     Universitaet Zuerich
     Physik Institut, 36H24
     Winterthurerstrasse 190
     CH-8057 Zuerich

     tel: 0041-1-6355742
	 0041-1-6355704 (fax)

     email: avollhar@physik.unizh.ch

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