From The RadioReference Wiki


TETRA is an acronym for TErrestrial Trunked RAdio. Tetra is an open voice standard developed by the European Telecom Standards Institute (ETSI) and is in use primarally overseas and in Europe. The first users to implement TETRA are the European public safety and emergency services, i.e. police, fire brigades, EMS, border control officials, etc. The existing public safety networks are coming to the end of their economic lifetime and TETRA provides the key features like equiment standardisation, direct mode, standardisation and last call set-up time for these services.

TETRA uses a 4-slot TDMA channel. Tetra systems uses both Voice and Control Channel. It uses by default air interface strong encryption and, as a result, there is no scanner available that can monitor TETRA Voice.

TETRA Modulation Characteristics
Property Value
Modulation π/4 DQPSK
Symbol rate 18000
Bit rate 36000
Slots/frame 4
Frame length 255 symbols (56.7ms)
Frame rate 17.65Hz

TETRA decoders

  • osmo-tetra - is a open source tetra decoder using linux, gnuradio and USRP1/2 for signal processing. The osmo-tetra project aims at implementing the sending and receiving part of the TETRA MAC/PHY layer. You can learn more about how TETRA works on its lowest level, but no decryption. Currently, it can receive, demodulate TETRA downlink signals of real-world TETRA networks display information about SYNC, SYSINFO, MM and CMCE PDUs.