TETRA & Emergency-Services Digital Radio
TETRA technology, TDMA time slots, emergency-services frequencies in Germany (380–400 MHz) and the legal situation under TKG §148 — what SDR users and radio amateurs need to know.
⚠ Legal situation in Germany
Intercepting emergency-services digital radio (TETRA) is, under §148 TKG a criminal offence — including passive listening, even if the content is encrypted. Merely making the signal visible in the spectrum is not technically prohibited. Decoding and listening: a criminal offence.
What is TETRA?
TETRA (Terrestrial Trunked Radio) is a European standard for digital professional radio, developed by ETSI (European Telecommunications Standards Institute) since the 1990s. Designed specifically for authorities, security forces and critical infrastructure.
TETRA core features
Digital encrypted voice (end-to-end possible) · direct mode (DMO) device-to-device · group communication · priority levels · GPS position transmission · SDS short data
TDMA — 4 time slots
TETRA uses TDMA with 4 time slots per 25 kHz channel. Up to 4 calls can run simultaneously on one frequency channel.
Technical parameters
| Parameter | TETRA value | Explanation |
|---|---|---|
| Channel spacing | 25 kHz | Spacing between two TETRA channels |
| Time slots / channel | 4 | Simultaneous calls per channel |
| Frame duration | 56.67 ms | One complete TDMA frame |
| Voice coding | ACELP | Clear at a low bit rate (7.2 kbit/s) |
| Net data rate | 28.8 kbit/s | Total per channel |
| Duplex | FDD | Transmit and receive on different frequencies |
| Duplex spacing | 10 MHz | Uplink/downlink spacing in the emergency-services network |
| Encryption | TEA2 | 128-bit key, not crackable — → details |
| Modulation | π/4-DQPSK | Phase modulation, robust against interference |
TETRA frequencies in Germany
| Frequency range | Direction | Use |
|---|---|---|
380.0125 – 389.9875 MHz | Uplink (device → base station) | Emergency-services digital radio Germany |
390.0125 – 399.9875 MHz | Downlink (base station → device) | Emergency-services digital radio Germany |
410 – 430 MHz | Range | Commercial TETRA systems, industry, public transport |
450 – 470 MHz | Range | Further commercial TETRA systems |
Emergency-services digital radio — who uses it?
| Organisation | Abbr. | Use |
|---|---|---|
| Police (federal & and states) | POL | Operational communication, situation briefings |
| Fire brigade | FW | Operational communication, group calls |
| Emergency medical service | RD / RTW | Control centre, vehicle-to-vehicle |
| Federal Agency for Technical Relief | THW | Disaster response |
| Federal Police | BPOL | Border protection, railways, aviation security |
| Customs | ZOL | Inspection and investigation duties |
| Emergency control centres | ILS/RLS | Dispatching, coordination |
BDBOS: The federal agency for emergency-services digital radio has, since 2015, operated the fully built-out nationwide network with over 4,500 base stations — nearly complete coverage including tunnels and buildings.
What can you receive — and what not?
| What | Technically | Legally | Explanation |
|---|---|---|---|
| See the TETRA signal in the spectrum | YES | YES | Only frequency and signal visible |
| Analyse the TETRA burst structure | YES | YES | Academic/technical analysis |
| Unencrypted TETRA voice | YES (rare) | NO | TKG §148 — prohibited anyway |
| Decode encrypted emergency-services voice | NO (TEA2) | NO | Encryption + TKG |
| Receive FM broadcast | YES | YES | Intended for the public |
| Receive aviation radio (passive) | YES | YES | Intended for the public |
| ADS-B aircraft data | YES | YES | Public, unencrypted |
| AIS ship data | YES | YES | Intended for the public |
| NOAA weather satellites | YES | YES | Intended for the public |