Re: Proposal: SDR-DSP receiver (was: Re: [amsat-bb] Cube sat and DSPs (was Re: cube sat))

[Kaj Wiik <wiik@xxxxxxxxxxxxxxxxx>]

On 15:02 2004-03-30, Achim Vollhardt wrote:

> 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!!

Huh, at two meters, you must be kidding!

What's wrong about
http://www.proaxis.com/~boblark/dsp10.htm
with
http://www.fidalgo.net/~wa7gxd/dspx.html

The sample rate should be compatible with the signal bandwidth, not the  
signal frequency. You'll end up throwing most of the data away and will  
have to deal with nasty problems with high speed logic signals when  
using high speed converters (e.g. 65 MSPS, 10 bit only!).

See also
http://www.arrl.org/tis/info/sdr.html
and
http://www.flex-radio.com/articles_files/index.htm

The sampling mixers seem to be very promising... (analog sampling with  
aliasing properties!).

Cheers,

Kaj
JA/OH6EH
----
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