The TETRA (TErrestrial Trunked RAdio) digital trunked two-way radio standard
was originally developed for public safety and other mission critical users. The aim
of its creators was to develop an open, interoperable standard to replace existing
analogue systems and utilise the advantages of new digital technology. TETRA
was developed by the European Telecommunications Standards Institute (ETSI),
although it was initially aimed at Europe, the standard has been successfully
adopted around the globe.
The advantage of having an open standard and air interface is that products from different
manufacturers can interoperate with each other at both infrastructure and terminal level. This
provides economies of scale and promotes competition, ensuring greater choice in the market.
TETRA Release 1 (1995) delivered eight key interfaces. However, it was agreed that not everything
inside the switching and management infrastructure – for example, the base station interface
– would be standardised. This was largely due to the fact that different manufacturers had
proprietary ways of configuring their networks for optimum performance and design flexibility.
This meant that vendors could differentiate their infrastructure solutions.
The standard interfaces include two air interfaces for trunked mode operation (TMO) between
radios and base stations, and direct mode operation (DMO) for direct communications between
radios without using the network