Friday, August 25, 2006

gps tracking system vehicle : GPS based

shows the block diagram of an IVU. The controller interacts with the GPS receiver, collects co-ordinates at predefined intervals, processes it and sends out to the communication link. Optionally in certain cases a man-machine- interface like a display with key board can be added for message communication between the driver and the base station.

The base station consists of a high-speed system running VTIS application software that will receive the position data from the vehicles and display on a digital map. It too will have the interface to the communication link. Enhanced features include video features, trace mode, history track, vehicle database, network support etc.

The most costly part of a VTIS is the data link. The data link, together with a suitable communication protocol, has to be selected after a thorough study of various parameters such as the bandwidth requirement, number of vehicles to be tracked, expandability, terrain, area of coverage etc. Sophisticated VTIS are linked to data bases that can support information about the vehicles such as the cargo, the temperature of storage of perishable goods, fuel consumption rate etc. Naturally, such systems demand data link with higher bandwidth. UHF links are suitable for short range without shadow region, as they require line of sight. Cell phone based systems demand minimum infrastructure investment, but is limited in coverage. On the contrary, LEO based systems are expensive and offer largest coverage. The recently introduced WAP and GPRS technologies hold great promises

When multiple vehicles are being tracked, a suitable communication protocol need to be established to avoid collision of radio signal. The simple technique is TDMA, where each IVU communicates during predefined time slots. This synchronization is easy in a GPS based IVU as the GPS receiver provides very precise time reference signal. However, TDMA based systems have limited expandability, flexibility and are known for under-utilization of bandwidth.

The alternative is polling technique. Here each vehicle is addressed by the control station and in response the IVU sends the information. This arrangement enables variable polling rate for different vehicles, non-polling of specific vehicles and expansion of polling list as new vehicles are added.

The relatively large investment needed for the communication link, makes VTIS an opportunity area for service providers. Fig. 4 shows the global market for GPS based VTIS in the next three years. In US and Europe many vehicle tracking service providers are already in operation. In a large country like India with a very long network of roads and long coastline, this opportunity area is yet to be exploited.

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