Today most vehicle tracking systems consists of a GPS receiver connected to a radio network such as GSM or GPRS. We have worked on the design of such equipment, recently providing a solution to add voice capabilites to a GPRS based system. Other data bearers that we have integrated into equipment include GSM, TETRA and UHF modems.

Many of our projects have involved trials to measure the propogation of signals in different environments and the effects of terrain and urban areas on performance. We have developed tools to assist with navigation and data bearer network verification and calibration.

In addition, our work with Racal and the Datatrak system has exposed us to alternative technologies for both navigation and the data-link. As well as integrating existing devices to create tracking and AVL solutions we also have the experience to create navigation products from the ground up.

Tagging

Experience had been gained through feasibility studies assessing the possible use of “tagging” technologies integrated into existing AVL systems. This knowledge is also applicable to standalone use of the tagging systems.

In the case of the “read only” tag systems, examples where the “tag” or the “reader” could be mounted on the moving vehicle were assessed. Also assessed were tagging systems where a two way data transfer between tag and reader was supported.

Mapping Systems

The mapping systems used in different countries require co-ordinate transformations to allow position reports to be accurately overlaid onto electronic maps. We can provided advice on mapping and can help to produce software to perform accurate transformations.

Datatrak AVL System

We have been involved in the development of the Datatrak systems since 1985. The system consists of a land based low frequency (LF) radio navigation system and a dedicated bi-directional UHF telemetry link. As well as the UK the system is also operational in Holland, Belgium, Austria, Malta, South Africa and Argentina.

The system can operate completely independently of other positioning system such as GPS. By comparing the relative phase of signals received from several LF transmitters the Vehicle Locator Unit (VLU) can calculate its position.

The network monitoring systems that are used to monitor and control each international network have been designed, built, installed and maintained by us. We also supplied a substantial part of the embedded software that is used in the VLU, the LF transmitters and the UHF base stations. The functionality of this software includes the DSP front end of the LF receiver, the position calculation algorithms and controlling the telemetry links.

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