| 摘要 |
PURPOSE:To display properly a current position without fail by displaying information on a current position detecting means installed separately instead of troubled position information when an abnormality is found on the position information of a moving body, which is obtained by using a radio wave from a satellite. CONSTITUTION:In terms of a system (GPS) 11 obtaining the current position of the moving body with the use of radio waves transmitted from artificial satellites 12a-12d, a signal received by an antenna 13 is processed by a current position calculating circuit 15 to calculate the current position, which is synthesized with information of a map information generating circuit 19 and displayed on a display device 20. Moreover a current position detecting circuit 23 measuring the current position without using the radio waves from the satellites 12a-12d is installed independently. If an abnormality detecting circuit 22 finds abnormalities relating to the output of the current position calculating circuit 15, the output of the current position detecting circuit 23 is displayed instead of that of the current position calculating circuit 15. |
