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Tetra is the acronym for Terrestrial Trunked Radio.
TETRA is a set of standards developed by the European Telecommunications Standardization Institute (ETSI) that describes a common mobile radio communications infrastructure throughout Europe. This infrastructure is targeted primarily at the mobile radio needs of public safety groups (such as police and fire departments), utility companies, and other enterprises that provide voice and data communications services.
All of these groups have been high-end users of private/professional mobile radio (PMR) or public access mobile radio (PAMR) technology. This is especially true in the areas of law enforcement and public safety, where fast and accurate field communications to and from a central office or dispatcher are often critical. TETRA is a standard solution for groups that use both PMR and PAMR.
Based on digital, trunked radio technology, TETRA is believed to be the next-generation architecture and standard for current, analog PMR and PAMR markets. TETRA actually takes its features from several different technological areas: mobile radio, digital cellular telephone, paging, and wireless data.
TETRA relies on digital trunking. These products are designed with the ability to transfer data at faster rates than seen before in mobile communications.
TETRA, which originally stood for Trans-European Trunked Radio, was renamed Terrestrial Trunked Radio after ETSI found widespread interest in the TETRA standards beyond Europe's geographic borders. ETSI has had a successful history of developing communications standards that later become accepted industry-wide, such as the Global System for Mobile Communications (GSMC) standard.
Efforts are currently underway to introduce TETRA standards in other parts of the world, including Denmark, China and the United States. (In the United States, another standard called APCO 25 is currently in use by public safety agencies. TETRA standards are currently being considered along with other standards for inclusion in a later phase of the APCO 25 Project.)
TETRA equipment has found its way to the secondary market and is available for amateur radio use.
In 2012, the FCC changed its Part 90 rules to permit unrestricted use of TETRA in the 450-470 MHz and 809-824/854-869 MHz spectrum bands. The action effectively extends the FCC’s temporary waiver issued last year that permitted TETRA deployments in the U.S. They are legal for amateur radio use in the United States and other countries.