INTEROPERABILITY AND DIRECT MODE BETWEEN TETRA AND EDACS

Abstract

The project investigates the mechanisms of interoperability and direct mode operation between two systems TETRA and EDACS. The basic aim of interoperability is to allow users from different agencies or areas, to use any base system of the network to communicate. This will allow agencies of the federal state / provincial government or private sector such as law enforcement, ambulance services and crisis management agencies to communicate more effectively with each other when required. Interoperability provides an smart solution at low or no signal strength of the parent base system. The interoperability between these two systems is a step towards developing a platform where all 6 systems of Project 25, TETRA, TETRAPOL, EDACS, DIMRS, FHMA, IDRA will be made interoperable. The inspiration for direct mode is that a subscriber may go in some region where he may not be in contact with any base system. For such an instance, direct access system would be developed, by which a mobile subscriber can talk to any other mobile subscriber in range, without use of base station. The motivation of this research was more pronounced after “2004 Indian Ocean earthquake and Tsunami” which distraught the communication infrastructures in their respective areas. In order to carryout multination disaster operations, it is important to introduce a system that is able to use all available means of communications, including swiftly deployable networks, to handle with large scale disasters and to apply precautionary measure. In this research, interoperability between two wireless communication systems TETRA (TErrestrial Trunked RAdio) and EDACS (Enhanced Digital Access Communications System) has been developed on basis of modulation identification. Both EDACS and TETRA are digital radio systems, working on GFSK and Pi/4 PSK as their parent modulation schemes. The individuality of these modulation schemes has been used for system identification through “Linear Predictive Coding”.