| 摘要 |
PURPOSE:To enhance position measuring accuracy by detecting the magnitude of the measuring error of the present position due to a satellite utilizing measuring means and that of the measuring error due to a running history position measuring means. CONSTITUTION:At first, the present position Pd (Xd, Yd) is measured by a running history position measuring means 9. Subsequently, the cumulative error DELTALd from a measuring start reference position Po (Xo, Yo) to the present position is calculated. Herein, when a satellite radio wave is received, the present position Pg (Xg, Yg) is measured by a satellite utilizing position measuring means 1. At the same time, the magnitude DELTALg of the measuring error of the present position is calculated by the means 1. Next, the magnitudes of the measuring errors DELTALd, DELTALg are compared with each other and, at the time of DELTALd>DELTALg, the measured value Pg (Xg, Yg) is displayed on a display device 16 as the present position. When no satellite radio wave is received, the measured value Pd (Xd, Yd) is set as the present position and, when the satellite signal is received but DELTALd<DELTALg is judged, the measured value Pd is read as the present position. |
