TETRA -Terrestrial Trunked Radio
TETRA is a digital radio standard common in Europe, Asia,and Indonesia. Tetra is a concept – a set of communications standards that welcome multiple manufactuers and accessory designers. Tetra radios offer a multiple range of functions and capabilities.
TETRA is a digital radio standard, developed in Europe for the European Public Safety market in the early 1990’s, with the first-generation networks deployed at the end of the 1990’s. TETRA is a standard written by the European Telecommunications Standards Institute (ETSI) with co-operation from users and manufacturers. With its growing popularity, it has been adopted as the preferred standard in many parts of the world and is now used by all sectors of the market. It is very adaptable in terms of size, capacity and functionality.
TETRA uses Time Division Multiple Access (TDMA) style of transmitting 4timeslots (digital channels) on one radio frequency carrier. One of those timeslots (channels) is a Master Control Channel (MCH), leaving three other timeslots (channels) for voice (TCH) or data traffic. Other carriers may be added to a base station (repeater site or tower), allowing for more conversations to happen per unit time. Tetra radios, often called terminals, may communicate as a group with other radios through a radio site (repeater station) in trunked mode, or with each other in a direct point-to-point (PxP) mode. The point to point or individual call types can be either semi-duplex (half duplex) or full duplex (as a mobile phone).
TETRA standards support a variety of communications solutions, such as voice (group, individual, emergency & DMO), data (status, SDS, packet, circuit switch), and location information.
The TETRA technology packsamount of feature capabilities, some of which are listed as follows:
- Digital audio using a trunked communication path (radio -> repeater -> radio) or point-to-point (PxP) using
either semi or full duplex
- Diversity receive antennas allow for less mobile and portable power levels
- Terminal Gateway Mode: a trunked mobile can relay signals from the trunk system to radios that are too weak or too far away to directly participate
- Multiple calling mode options: PxP Telephone Style, PxP PTT Style, and traditional group calling
- Connectivity to a digital phone system, such as Asterisk, is available. Make a phone call from your radio to
your internal PBX, or an external line!
- Optionally integrated GPS boards allow for tightly integrated Automatic Vehicle Tracking (AVL) options
- Saftey feature – man down capability: the radio “automatically sends a message to a dispatcher”
if a worker becomes unresponsive
- Saftey feature – radios check themselves against the trunk system, and warn the user if they travel out of coverage zones
- Depending on radio model, they may be able to send and receive text messages (SDS)
- Cellular-like handover from one tower site to another as the radio moves around the coverage area
- Dynamic power control on the network to reduce terminal transmitter power which saves on battery
life and consumption
- Optional dispatcher software allows for dynamic grouping of radios for a specific event, such as responding to a car crash, or servicing an airplane at the terminal gate after it lands