brmlab

On Debian install libcmocka-dev libglib2.0-dev libjson-c-dev.

Clone the repository, do what README says.

• The scripts in demod/ directory eat data from SDR and spit out demodulated bits.
• apps/tetrapol_dump eats these bits and decodes metadata. Use -t TCH or -t CCH to decode the right channel (switch to the other one if it does not work).

Scan for Tetrapol traffic. It is 12.5kHz wide buzzing (when demodulated as FM) usually in the 380-420MHz band.

Compute the ARFCN of your station. We believe it is (f-358400000)/12500. E.g. a station at 394425 kHz is channel number 2882.

Run the demodulator, passing tetrapol_dump to its pipe. E.g.

./demod.py -c 2882 -p 44 -g 40 -O "tetrapol_dump -t TCH"

To save raw bits for further experiments, you can for example add the “tee” command to the pipe.

If the dumping mysteriously fails, you probably have wrong type of channel. There are CCH channels (broadcast and control messages) and TCH channels (actual traffic is happening here).