NAVIGATION SYSTEM, ACCOUNTING METHOD THEREOF AND BACKUP SYSTEM OF MAP DATA

PROBLEM TO BE SOLVED: To recover map data when a navigation system is damaged or stolen in a navigation system downloading small area data of a map by providing a version administration function of map data. SOLUTION: When a small area data of a map is downloaded from the memory device or the server device of a navigation system, the version information of the map is also downloaded to administrate the version information of the small area data in the navigation system. When the map data are enciphered, a decoding key for decoding the necessary small area data and use conditions are downloaded from the server device, and the key information is administrated in the navigation system. For enabling one to recover the map data when they are lost by damage of the memory device or theft of the vehicle, the version information of the small area data is also administrated in the server device. COPYRIGHT: (C)2005,JPO&NCIPI