| 摘要 |
PURPOSE:To enable the execution of two-dimensional position measurement of high precision, by calculating an accurate altitude with reference to map informations stored beforehand and pseudo-distance data when an automobile passes through a reference point. CONSTITUTION:A position computing unit 16 to which pseudo-distance data obtained by a GPS receiver element 12 and accurate crossing position data obtained from a map storage element 20 are inputted is provided. When an automobile passes through a reference point, an accurate altitude is calculated by an altitude computing unit 14 on the basis of map informations stored beforehand in the map storage element 20 and the pseudo-distance data received and measured from radio waves of three satellites by the GPS receiver element 12, and the altitude thus obtained is used for two-dimensional position measurement when two-dimensional navigation is conducted thereafter. |
