| 摘要 |
A global positioning system for positioning a mobile object such as an automobile in a global geometrical region includes a GPS receiver for receiving radio waves from a plurality of satellites and outputting either two-dimensional position data indicative of the present position of the mobile object in a two-dimensional position measurement mode or three-dimensional position data indicative of the present position of the mobile object in a three-dimensional position measurement mode. An altimeter detects a relative altitude of the mobile object and outputs relative altitude data indicative of the detected relative altitude. A present position output unit calculates present position data indicative of the present position of the mobile object solely based on the data from the GPS receiver while the GPS receiver is operating in the three-dimensional position measurement mode. When the GPS receiver operates in the two-dimensional position measurement mode, the present position output unit calculates present position data indicative of the present position of the mobile object based on the two-dimensional position data and the relative altitude data. The calculated present position data are sent to a display which displays the two-dimensional position of the mobile object and also the altitude data. |
