| 摘要 |
PURPOSE:To immediately determine a change in position measurement accuracy to avoid misrecognition of an automobile position or the like by having a position measurement accuracy determining means for determining accuracy of a measured current position and an advancing direction while a display means varies display forms of the current position and the advancing direction according to the determined measurement accuracy. CONSTITUTION:A system controller 5 reads a reception situation or the like from a satellite as a position measurement accuracy determining means from a GPS position measuring device 4 and determines whether calculation of an automobile position depends on three satellites or on four satellites which provide high accuracy. At the same time it determines whether advancing direction information is highly accurate or not according to the output. During low speed travel, the output of the advancing direction information is at low accuracy. The system controller 5, when it determines the position measurement accuracy, varies display forms of a current position and the advancing direction of a display according to the determined measurement accuracy. Therefore change in measurement accuracy can be immediately discriminated, thereby avoiding misrecognition of the automobile position, etc. |
