Re: [Discuss-gnuradio] Re: How to scan the whole ISM band?

[Martin Braun]

On Tue, Jul 15, 2008 at 11:49:20AM +0200, Patrick Strasser wrote:
> You can receive 32MHz at a time, but you are limited to 8MHz through the 
> USB bus. You cannot scan the whole 2.4Ghz ISM band at a time, but you can 
> step through it. If you want to detect unused frequencies you'd probably 
> just want to calculate the power over a reasonable time interval to decide 
> if some is using the band in question.

If you just want to find spectrum holes, you might be able to teach the
FPGA some kind of compressed sensing to increase your monitored
bandwidth (I guess factor 10 is feasible, if you can manage to install a
stable compression scheme on the FPGA - no idea how difficult/possible
this is).

IMHO, this is pretty funky stuff, but also quite tough math. [1] is
where you can find pretty much everything about compressed sensing, [2]
is what I'd suggest for compression. [3] and [4] are about using compressed
sensing for wideband spectrum hole detection.

To be honest, I've never actually seen this outside the
pencil+paper/matlab world, and chances are high you want something
simpler than this. However, if the odd chance is you are prepared to go
through the effort, I'd be anxious to find about if you were successful :)

Cheers,
MB

[1] http://www.compressedsensing.com/
[2] http://www.dsp.ece.rice.edu/cs/random-filter-pub-03-web.pdf
[3] Zhi Tian; Giannakis, G.B., "Compressed Sensing for Wideband
Cognitive Radios," Acoustics, Speech and Signal Processing, 2007. ICASSP
2007. IEEE International Conference on , vol.4, no., pp.IV-1357-IV-1360,
15-20 April 2007
[4] Zhuizhuan Yu; Hoyos, S.; Sadler, B.M., "Mixed-signal parallel
compressed sensing and reception for cognitive radio," Acoustics, Speech
and Signal Processing, 2008. ICASSP 2008. IEEE International Conference
on , vol., no., pp.3861-3864, March 31 2008-April 4 2008


-- 
Martin Braun
Institut fuer Nachrichtentechnik
Universitaet Karlsruhe

http://www.int.uni-karlsruhe.de

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