TETRA Private Mobile Radio (PMR)
TETRA is a modern standard for digital private mobile radio (PMR) and public access mobile radio (PAMR).
Work started on the development of the TETRA standards in 1990 and has relied on the support of the European Commission and the ETSI members. Experience gained in the development of the GSM cellular radio standard, as well as experience from the development and use of trunked radio systems has also been used to fashion the TETRA standard. In addition to this the process has gained from the co-operation of manufacturers, users, operators and industry experts. With this combined expertise the first standards were ready in 1995 to enable manufacturers to design their equipment to interoperate successfully.
TETRA allocates the channels to users on demand in both voice and data modes. Additionally national and multi-national networks are available and national and international roaming can be supported. For civil systems in Europe the frequency bands 410-430 MHz, 870-876 MHz / 915-921 MHz, 450-470 MHz, 385-390 MHz / 395-399.9 MHz, have been allocated for TETRA. Then for the emergency services in Europe the frequency bands 380-383 MHz and 390-393 MHz have been allocated. In addition to this, the whole or appropriate parts of the bands between 383-385 MHz and 393-395 MHz can be utilized.
Low speed packet data as well as circuit data modes are available, along with some form of encryption. The systems makes use of the available frequency allocations using time division multiple access (TDMA) technology with four user channels on one radio carrier with 25 kHz spacing between carriers.
The first ruggedized high-speed smartphone based on the TETRA network was launched on 26 May 2011
Read more about this topic: Professional Mobile Radio
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