| 摘要 |
PROBLEM TO BE SOLVED: To increase the economy of a positioning system which uses portable terminals to transmit position data to a positioning server and to reduce the power consumption of the system. SOLUTION: When a GPS positioning part 7 determines the position of a portable terminal 4 and acquires position data, the portable terminal 4 compares its position as indicated, according to the position data acquired by the GPS positioning part 7 to its position as indicated, according to the position data previously transmitted from the positioning server 3; only if the difference between these positions is equal to or greater than a reference distance, the position data acquired by the GPS positioning part 7 is transmitted to the positioning server 3. With a very small value set as the reference distance, the position data will not be transmitted to the positioning server 3, if the terminal 4 remains at approximately the same position over a given period of time, so that the cost and power required for transmission can be reduced.
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