Also known as: TETRAPOL
TETRAPOL is a digital professional mobile radio (PMR) standard for trunked public-safety networks that, unlike TETRA, uses FDMA — one radio carrier per channel — and GMSK modulation. It is a distinct, competing technology to TETRA, widely deployed by police, gendarmerie, and security services across Europe and beyond.1
Overview
TETRAPOL grew out of a French system (Matra Communication, later EADS/Airbus) and became the second major digital public-safety standard in Europe alongside TETRA. Its defining architectural choice is FDMA rather than TDMA: every logical channel occupies a separate narrowband carrier. This keeps the transmitter design simple and gives good range and building penetration at the cost of the per-channel spectral packing that TDMA can achieve. Networks are trunked, with dedicated control channels signalling call setup, registration, and encryption.
Technical characteristics
| Property | Value |
|---|---|
| Access | FDMA (one carrier per channel) |
| Channel | 10 kHz (some 12.5 kHz) |
| Modulation | GMSK at 8000 bps |
| Bit shaping | Gaussian-filtered continuous-phase |
| Vocoder | RPCELP analysis-by-synthesis |
| Encryption | Native end-to-end and air-interface options |
| Bands | Typically 70–520 MHz, deployment-dependent |
GMSK is a constant-envelope, continuous-phase scheme, which lets TETRAPOL radios use efficient non-linear power amplifiers and gives the signal a compact spectrum — the same modulation family used by GSM and many other PMR systems.
History
Development began in the late 1980s in France, with the first large networks — the gendarmerie’s Rubis and the police Acropol systems — deployed through the 1990s. The TETRAPOL Forum published the Publicly Available Specification (PAS) to encourage wider adoption. The technology spread to public-safety users in Spain, Switzerland, Czechia, Mexico, and other countries, positioning itself as the FDMA alternative to ETSI’s TDMA-based TETRA.
Deployment
TETRAPOL remains in service in numerous national and regional police, gendarmerie, and emergency networks, particularly in France, Spain, and parts of central and eastern Europe. Because most of this traffic is encrypted for operational security, it is heard but rarely intelligible to third parties.
Decoding it with GopherTrunk
TETRAPOL is not decoded by GopherTrunk. Its FDMA/GMSK physical layer differs from the C4FM and π/4-DQPSK families GopherTrunk targets, and its proprietary vocoder and pervasive encryption place operational traffic out of reach. GopherTrunk decodes clear and known-key signals only; TETRAPOL is documented here for identification and context rather than as a supported decode target. For a supported European public-safety standard, see TETRA.