Friday, August 25, 2006

gps tracking system vehicle : GPS based vehicle tracking system

Of all the applications of GPS, vehicle tracking and navigational systems have brought this technology to the day-to-day life of the common man. Today GPS fitted cars; ambulances, fleets and police vehicles are common sights on the roads of developed countries. Known by many names such as Automatic Vehicle Locating System (AVLS), Vehicle Tracking and Information System (VTIS), Mobile Asset Management System (MAMS), these systems offer an effective tool for improving the operational efficiency and utilization of vehicles.

The switching off of SA has improved the accuracy of GPS to better than 30 meters, which makes it an ideal position sensor for vehicle tracking systems without the overhead of DGPS.

GPS is used in vehicles for both tracking and navigation. Tracking systems enable a base station to keep track of the vehicles without the intervention of the driver where, as navigation system helps the driver to reach the destination. Whether navigation system or tracking system, the architecture is more or less similar. The navigation system will have convenient, usually a graphic, display for the driver which is not needed for a tracking system. Vehicle Tracking Systems combine a number of well-developed technologies. Irrespective of the technology being used, VTS consist of three subsystems: a) In-vehicle unit (IVU), b) Base station and c) Communication link. The IVU includes a suitable position sensor and an intelligent controller together with an appropriate interface to the communication link. Thanks to the US Government announcement of 911E regulation, radio based position technology has witnessed a spurt of developmental activities.

Network Overlay Systems use cell phone infrastructure for locating vehicles. The cell centers with additional hardware and software assess the time of arrival (TOA) and angle of arrival (AOA) of radio signals from vehicles to compute the position of the vehicles. This information is sent to the tracking centre through the cell link or conventional link. Another technique used for locating vehicles computes the time difference for signals from two cell centers to reach the vehicle. This computation is made in the IVU and the position information is sent to the tracking centre through the cell phone link. A more common technique used is direct radio link (DRL). In this system dedicated radio infrastructure is used along with special IVU to compute vehicle location. However all these techniques impose limitation on the operational area. Alternatively, embedded GPS receivers provide absolute position co-ordinates at any point, without any area restrictions.

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6:29 AM  

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