Patent ID: 6480784
Filing Date: 2002-11-12
Classification: G01C

Abstract:
A position data decimation apparatus for use in a mobile body navigation apparatus having position calculation means for calculating successive positions of a mobile body which transports said apparatus and position recording means for recording data expressing a plurality of said positions, wherein said position data decimation apparatus comprises:position accuracy indication means for generating, in conjunction with each of said calculated positions, corresponding indication information relating to a positioning accuracy of said calculated position; and position accuracy judgment means for selecting data expressing specific ones of said positions, to be recorded by said position recording means, with said selection based upon judgment of said corresponding indication information, wherein said position calculation means comprises absolute position sensing means for periodically calculating said positions of the mobile body as respective absolute positions based on information from signals transmitted from navigation satellites, and relative position sensing means for periodically calculating said positions of the mobile body as relative positions at times between successive calculations of said absolute positions, and wherein said position accuracy indication means comprises means for calculating, for each of said relative positions, as said indication information: an absolute positioning error of an absolute position which precedes said relative position, a relative positioning error of said relative position, and the sum of said absolute positioning error and said relative positioning error, as a total positioning error for said relative position.