Tetrapol
Tetrapol, a digital trunked radio system that is a further development of the French MC 9600 system from the Matra company, has evolved as a competitor to the Terrestrial Trunked Radio( TETRA) standard.
The method was further developed by an industry consortium and is not standardized. The consortium included Matra, the European Aeronautic Defense and Space Company (EADS) and Nortel Networks. Like Tetra, Tetrapol offers the advantages of Professional Mobile Radio( PMR) such as fast call set-up, direct call, group call, direct mode without Tretrapol network, Direct Mode Operation( DMO), emergency call, paging, data transmission, transition to public mobile radio networks and Internet access. The system operates on narrowband channels with a bandwidth of 12.5 kHz.
There are over 60 Tetrapol networks in 28 countries, with the most implemented in France. These are used primarily by security organizations such as police, border guards, customs and ambulance services because of the high level of interception security.
Tetra and Tetrapol differ technically and are not compatible in the air interface; for example, Tetrapol's channel access method is Frequency Division Multiple Access( FDMA), while TETRA's is Time Division Multiple Access( TDMA). In addition, the two systems use different compression methods.