Re: [Discuss-gnuradio] Squelch block, AGC function and scanner example

[Frank Brickle]

Martin Dvh wrote:

> I hope also to find a way to determine what kind of 
signals they are (FM, AM, TV, FSK)
>
> This way you get a list of everything there is to receive 
with your current frontend.

A non-trivial task. Robust classification in this setting 
means doing selective channel downconversion and making 
repeated sequential spectral observations on the channels.

In broadband, this usually requires maintaining a 
substantial delay line from which to grab and process the 
selected channels. In commercial systems like the Agilent 
E3238S the delay line has been the one of the most expensive 
components.

If you're interested, I wrote a brief expository article 
about automatic signal classification using probability 
models of power spectra that appeared in the December 2003 QEX.

Frank