One of the leading standards in digital radio is TETRA, which is an open standard for digital trunked radio systems. TETRA stands for TErrestrial TRunked RAdio. TETRA is opening an even more international PMR market with widely harmonized frequencies. The European Telecommunications Standards Institute (ETSI) that joins the forces of network operators, national administrations, equipment manufacturers and users defines the standard. Terrestrial trunked radio (TETRA) is the modern digital private mobile radio (PMR) and public access mobile radio (PAMR) technology for police, ambulance, fire, transport and security services.
TETRA is a purpose built technology that offers public safety and security organisations major advantages over conventional radio systems to. It was developed to meet the needs of the most demanding professional radio users who need fast one-to-one and one-to-many radio communication using voice and data in their daily work. Users are typically public safety and security organisations such as police, fire and rescue forces. TETRA fulfils the needs of professional users and replaces old analogue and proprietary radio communication systems that no longer meet professional radio-communication needs.
TETRA is the first truly open international standard for the digital professional mobile radio environment.
TETRA is the first truly open international standard for the digital professional mobile radio environment.
TETRA specifies a set of open interfaces and services for new professional mobile radio systems.
TETRA offers the automatic operation and frequency efficiency of trunking combined with the terminal autonomy of a conventional PMR. TETRA has a multi-mode capability by combining these two modes, trunking and direct (conventional), into single terminal equipment, and it also provides the standardised way of inter-working between these two modes. TETRA is designed to offer bandwidth-on-demand, a facility to have a variable amount of bandwidth allocated for the call duration, depending on the application.
TETRA-BASICINTERFACES
To ensure an open multivendor market, TETRA specifies the following essential interfaces:
1. Air Interface ensures the interoperability of terminal equipment from different manufacturers.
2. Terminal Equipment Interface (TEI) facilitates the independent development of mobile data applications.
3. Inter-System Interface (ISI) allows the interconnection of TETRA networks from different manufacturers.
4. Direct Mode Operation (DM0) guarantees communication between terminals also beyond network coverage
DMO-most attractive feature of TETRA
4. Direct Mode Operation (DM0) guarantees communication between terminals also beyond network coverage
DMO-most attractive feature of TETRA
DMO is the term used by the TETRA industry to describe the ability of TETRA radio terminals to communicate directly with each other (like ‘Walkie-Talkies’) independent of the Trunked Mode Operation (TMO) network. DMO is not new and has been a fundamental mode of operation by many traditional PMR user organisations for several decades. The primary requirement for DMO in TETRA has been brought about by the need to balance the RF coverage, Grade of Service (GoS) and reliability of a network with that of the network’s overall cost.
Typical DMO Applications
The typical applications for DMO are local area communications outside the TMO network and range extension of the TMO network. To improve communication capabilities when using these applications, facilities are provided to enable DMO users to be contacted by TMO network users when operating outside the network as well as facilities to enhance local area DMO RF coverage performance.
APPLICATIONS
The TETRA-system is in use by the public sector in many countries. In India , Military College of Telecommunication Engineering (MCTE) uses TETRA (at Mhow, Indore, Madhya Pradesh), Kerala police(AD100) also uses this standard for communication. Recently Center For Development of Advanced Computing(CDDAC) -Trivandrum has developed a new communication system named ‘DHRUV’ for enabling communication during natural calamities ,accidents etc. which also uses TETRA as its communication standard.
The main areas of application of TETRA are listed below-
¨ Military
¨ Police and paramilitary forces
¨ Fire Force
¨ Railways
¨ Communication in Rural areas
¨ Aid in emergency due to natural calamities
¨ Life saving communication in coasts
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