| 摘要 |
PROBLEM TO BE SOLVED: To reduce data processing and to eliminate a memory in which a map for display is stored in the case of detecting and displaying the current position by utilizing radio waves from a base station. SOLUTION: A mobile terminal device 1 receives radio waves from base stations 21 when a GPS receiving part 11 can not be used, measures its field strength, also extracts base station identification information and transmits them to a service center 3. The center 3 acquires the installed positions of the base stations corresponding to identification information of the stations 21, calculates the current position of the device 1 on the basis of the acquired installed position and its measured field strength and also acquires a map corresponding to the current position from a map database. Since the center 3 transmits the current position and the map to device 1, the device 1 shows the map including the current position on a displaying part. |
