Communications navigation system, and navigation base apparatus and vehicle navigation apparatus both used in the navigation system

A navigation base apparatus for use in a communications navigation system in which data is transmitted and received by means of wireless communication between the navigation base apparatus provided at a navigation base and a navigation apparatus provided in a moving body such as a vehicle wherein the navigation apparatus is adapted to transmit at least data concerning the current position of the moving body and the destination thereof to the navigation base apparatus, said navigation base apparatus comprising:

• navigation data storing means for storing navigation data including detailed map information;
• means for determining a recommended route based on the received data of the current position of the moving body and the destination thereof, and for extracting data of the recommended route from the navigation data stored in the navigation data storing means, and then transmitting the extracted data to the navigation apparatus;
• and
• intersection judgement means for determining an angle between roads on said recommended route into and out of each intersection and fork on said recommended route and for identifying each intersection and fork for which said angle is less than a predetermined value as a course-change point;
• wherein the navigation base apparatus is adapted to be able to extract detailed map information limited to only that for an area surrounding the course-change point on the recommended route, from the navigation data stored in the navigation data storing means, and then transmit the extracted detailed map information to the navigation apparatus.

A navigation apparatus for use in a communications navigation system in which data is transmitted and received by means of wireless communication between a navigation base apparatus provided at a navigation base and the navigation apparatus provided in a moving body such as a vehicle wherein the navigation base apparatus has navigation data storing means for storing navigation data including detailed map information, means for determining a recommended route based on data for the current position of the moving body and the destination thereof, received from the navigation apparatus, and for extracting data of the recommended route from the navigation data stored in the navigation data storing means, and then transmitting the extracted data to the navigation apparatus;

• and wherein said navigation apparatus comprises:
• intersection judgement means for determining an angle between roads on said recommended route into and out of each intersection and fork on said recommended route and for identifying each intersection and fork for which said angle is less than a predetermined value as a course-change point;
• means for transmitting at least data concerning the current position of the moving body and the destination thereof to said navigation base apparatus;
• and
• means for displaying indication of travelling direction of the moving body at the course-change point based on the detailed map information received from the navigation base apparatus;
• and
• wherein the navigation apparatus is adapted to receive from the navigation base apparatus detailed map information limited to only that for an area surrounding the course-change point on the recommended route which is extracted from the navigation data stored in the navigation data storing means based on the received data concerning the current position of the vehicle and the destination thereof.