Patent ID: 6643581
Filing Date: 2003-11-04
Classification: G01C,G08G

Abstract:
A navigation system comprising:a database holding real-time information indicating a ground state; a server receiving positional information including a present position of a client through a communication network, determining, as an information extraction range, a certain range on a map wider than a surrounding area of said present position based on said positional information, extracting, as real-time information to be transmitted, real-time information falling within said information extraction range and having a transmittable largest data quantity from said database, adding a header identifiable by said client to the extracted real-time information and transmitting the header-added real-time information through said communication network at random; and a navigator transmitting said positional information to said server through said communication network, receiving information from said server through said communication network, detecting said extracted real-time information from the received information while using said header, and displaying the detected real-time information.