| 摘要 |
PROBLEM TO BE SOLVED: To provide a positional information providing system and a mobile device used in it for surely acquiring positional information of a vehicle traveling in an optional place and surely providing the positional information and preventing congestion of a communication network even when a massive quantity of information is acquired at once for preventing reduction in information responsiveness. SOLUTION: The positional information providing system is provided with a mobile device determining its own position and a central device 5 communicative with the mobile device. The mobile device successively acquires vehicle information for identifying a vehicle 2 from an identification member installed on the vehicle 2 in the vicinity of the mobile device, and in every acquisition of the vehicle information, calculates a difference between the previously acquired vehicle information. If it is determined that the calculated difference exceeds a predetermined threshold value, the mobile device transmits the acquired vehicle information with the positional information showing the determined own position to a positional information providing device, and the positional information providing device receives the vehicle information and the positional information transmitted from the mobile device to store these pieces of information. When receiving a search condition including the vehicle information, the positional information providing device oututs the stored vehicle information and positional information according to the received search condition. COPYRIGHT: (C)2008,JPO&INPIT
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