TETRA
From The RadioReference Wiki
Contents
Overview
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 primarily 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 equipment standardisation, direct mode, encryption 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 can use strong encryption on the air interface, and this is usually used on sensitive traffic (police etc), but commercial networks are often unencrypted. AOR receivers AR-DV1, AR-DV10 and AR5700D can monitor TETRA Voice (the first two models require a paid key to follow TETRA trunking) and software to do it exists (SDR# w/TETRA plug-in, telive, w-code, and probably others).
| 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.
- OpenEar
- telive - telive is a frontend for patched osmo-tetra and friends: osmo-tetra-sq5bpf, libosmocore-sq5bpf. Telive will display a console showing current SSI numbers, and have the option to log signalling information, decode some SDS messages, record traffic (and recompress it into OGG files), and do live listening. The program will decode some location protocols, and provide the decoded data in a KML file (readable by Google Earth and other software). The receiver uses an rtl-sdr dongle and gnuradio (3.6, or 3.7.5 or higher), but the software was also reported working with a funcube dongle and USRP. The software can process multiple channels at once, and gnuradio-companion receiver flowgraphs are provided to monitor multiple channels with one sdr dongle. Please read the documentation and the Tetra decoding Thread on Radioreference. All software runs on linux and is fully opensource (except for the ACELP codec from ETSI).
- TETRA Trunk Tracker
- TETRA Listener
- Updated Meteo and TETRA plugin Note: Site is in Russian. Use Google Translate
- These are commercial packages (very expensive) which can analyze and decode numerous modes, including TETRA
Receivers
Links
- TETRA Facts and Overview
- TETRA MOU Home Page - this is the web site for the TETRA MOU (Memorandum of Understanding) which is the organization responsible for developing and publishing the TETRA Digital Trunked Radio Standard.
- Motorola's TETRA Home Page - lots of information here regarding Motorola's entry into the TETRA market, news, information, and product descriptions.
- ETSI Telecom Standards - TETRA Information and technical documentation on the ETSI Standards Website.
- TETRA Digital Standard Information - Excellent web site run by Nokia which outlines the TETRA standard and its uses for public safety and commercial environments.
- TETRA on Wikipedia
- TETRA Forum Poland - best source of information about TETRA industry in Poland
- OSMOCOM TETRA FAQ - OsmocomTETRA Frequently Asked Questions
- RadioReference Links
- See the Tetra decoding Thread and TETRA Trunk Tracking Demonstration Thread for use with an SDR.
Return to Wiki page: Trunked Radio Systems, DMA Scanners and Trunking, CENTRACOM Elite
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