Abstract
Terrestrial Trunked Radio (TETRA) is a digital trunked mobile radio standard developed by the European Telecommunications Standards Institute (ETSI). The purpose of the TETRA standard is to meet the needs of traditional Professional Mobile Radio (PMR) user organisations, including Public Safety, Transportation, Utilities, Government, Military, Commercial and Industryand Oil and Gas. In practice, TETRA is a suite of standards covering different technology aspects - air interfaces, network interfaces, services and facilities. This article contains information about the TETRA Association; the TETRA Rail Forum; and includes a Case Study from Denmark.