tetra-toolkit

Tools and documentation for TETRA decoding.

The installation instructions are given for Ubuntu 24.04.

Install gnuradio and gr-osmosdr

sudo apt install git gnuradio gr-osmosdr

Download the GRC file

git clone https://github.com/Tim---/tetra-toolkit

The GNU Radio Companion files are located in the grc folder.

First, you must build the TETRA Demod block :

grcc grc/tetra_demod.grc

Next, open the file grc/tetra_rx.grc in GNU Radio Companion, and execute it.

Using the GUI

On the "Coarse" tab, enter the "Center Frequency" of your Tetra downlink. The channel should be located at offset 0 on the left plots.

You can use the "Channel" and "Constellation" tab to check that your signal is clean.

Use the controls on the right (fine freq, ppm, gain) to get a nice signal.

Getting the bits

Once everything is good, the bits are sent by chunks over UDP to 127.0.0.1:1234. Now we need an application that actually interprets the bits.

osmo-tetra

Download and build osmo-tetra

sudo apt install git build-essential libosmocore-dev
git clone https://gitea.osmocom.org/tetra/osmo-tetra.git
cd osmo-tetra/src
make

Execute tetra-rx

sudo apt install netcat-openbsd
mkdir /tmp/out
nc -l -u -p 1234 | ./tetra-rx -d /tmp/out /dev/stdin

You should see some output on the console.

Also, the decoded packets are sent over GSMTAP to 127.0.0.1:4729. You can use Wireshark to see the packets:

sudo apt install wireshark
wireshark -k -i lo -f 'udp port 4729'