= TETRA =
TETRA ('''TE'''rrestrial '''T'''runked '''RA'''dio) is a professional mobile radio (PMR) system used
by public (police, military, emergency services) as well as private companies (public transportation,
harbour, industrial/chemical plants, power/electricity companies, etc.)
It is specified by the [http://www.etsi.org/ ETSI] (European Telecommunications Standardization Institute).
The specifiations can be downloaded from http://pda.etsi.org/
The main specification document is * ETSI EN 300 392-1 (Voice plus Data (V+D); Part 1: General network design) * ETSI EN 300 392-2 (Voice plus Data (V+D); Part 2: Air Interface (AI)) * ETSI EN 300 395-2 (Speech codec for full-rate traffic channel; Part 2: TETRA codec)