GRCon12: Seeber - Blind signal analysis with GNU Radio
Channel: Thomas Rondeau
Date: 2013-08-03

There are quite a few tricks that can be employed when attempting to deconstruct an unknown signal, many of which can be easily implemented using GNU Radio.

I will cover a number of these 'tricks' that would allow someone to peel back the layers step-by-step: modulation type/order, symbol rate, FEC, and then various signal-specific properties (scrambling, identifying structure, guard interval, frame duration, etc). For each I will show the appropriate construction in GRC.

The 'tricks' essentially rely on ideas drawn from cyclostationary analysis and the side-effects of using certain modulations. The main signals I will centre the talk around are those I captured from a geostationary satellite (PSK downlinks), and from HF (OFDM Digital Radio Mondiale, STANAG). The techniques can of course be applied to normal terrestrial signals, too.

Other tools, such as GNU Plot, are also used to visualise the output from the DSP done in GNU Radio.

(The link given relates exclusively to the OFDM work. However the majority of the discussion would be based on the PSK sat signals, which is touched on in the second-half of: http://www.youtube.com/watch?v=Vn-dpUegUDQ)

http://wiki.spench.net/wiki/OFDM