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Re: [linrad] RE: Detecting phase modulation with undersampling

Krzysztof Kamieniecki wrote:

>I'm probably confused but with the processing power of the DSP that you have why
>not just create a digital version of the analog circuits you have used in the
>past. You may need to downconvert and decimate the input signals first.
>  
>
In theory that sounds good, but it is not too obvious (to me anyway), 
the best way to do that. The DSP is fast, but not fast enough to do 
real-time processing of a 70 MHz signal directly. The key will be the 
undersampling, but that, along with the fact I can't continuously pass 
data from the A/D to the DSP due to the limitaitions of the bus between 
them, causes even more complications.

>You may also want to look at GNURadio, if you haven't yet, it is a Software
>Radio Toolkit. 
>
I will do that.

>Although it is PC based you could prototype your design using it. You can post this question to the GNURadio list as well, there seem to be a
>lot of people there with a wide range of signal processing interests and
>experiences.
>
Knowing GNU stuff, it will probably run on any UNIX system, which is a 
good thing. I rather have an aversion to PC's - especially if they run 
Windoze. At home I have UNIX computers from Sun, IBM, SGI, Dec, HP (plus 
any I forgot). I find testing software on lots of platforms a very good 
way to find bugs.

One of my programs for analysing transmission lines

http://atlc.sourceforge.net/

has been built on various UNIX systems, but including a very old Cray 
supercomputer and a Sony Playstation 2!!! I personally built it on the 
Cray (which caused a few problems due to the fact the size of a short is 
8 bytes, rather than the 2, which it has been on any computer 8, 16, 32 
or 64 bit computer I have come across). Someone else went to the trouble 
of building it on a Sony Playstation 2. It wil also build on Windoze.

-- 
Dr. David Kirkby PhD CEng MIEE
Senior Research Fellow
Department of Medical Physics
University College London
11-20 Capper St
London WC1E 6JA
Tel: 020 7679 6406 (direct line)
Tel: 020 7679 6262 (office)
LINRADDARNIL
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