| 摘要 |
PURPOSE:To enable highly accurate measurement of a position, by measuring a position by a first or second position measuring means depending on whether the number of satellites is above or below a specified value. CONSTITUTION:A received signal from an antenna 1 undergoes a frequency conversion 2 and takes a correlation by a false distance measuring device 3 with a P-N code generated inside. A correlation output signal from the measuring device 3 is inputted into a position measurement arithmetic unit 5 through an orbit data decoder 4 or directly. The arithmetic unit 5 determines altitude, horizontal position, speed and bearing and the results, the altitude and the like, are displayed 6. P (positional) DOP (dilution of precision), V (vertical) DOP and H (horizontal) DOP satellites selector 7-9 select optimum GPS (global positioning system) satellites separately based on a data from the arithmetic unit 5. A receiving satellite switch 11 is operated to perform a position measurement by a radio wave from the selector 7 when the number of common satellites is 0, or by a radio wave from the selector 8 or 9 selected 10 when it is not 0. This enables highly accurate position measurement. |
