| 摘要 |
PROBLEM TO BE SOLVED: To discriminate between an upper road and a lower road of a multi-tiered road without adding new unit and component to a navigation apparatus, by discriminating them as the upper road when a right or left side of a satellite is observed toward an advancing direction or as the lower road when it is not observed. SOLUTION: In the case of traveling an own vehicle on a multi-tiered road, an upper road and a lower road are discriminated as the upper road when a right or left side of a satellite is observed toward an advancing direction or as the lower road when the right or left side of the satellite is not observed. For example, at a vehicle A traveling on a road of the upper road, a reception from a GPS satellite existing in the sky is not shielded except by a part of a first building. At a vehicle B, there is nothing to shield it in the sky ahead thereof, but the sky cannot be observed by shielding by the building and an elevated facility in the right and left sky. At a vehicle C, the sky cannot be observed except a part ahead thereof. Whether a range of a GPS satellite to be observed is wide or narrow is quantitatively handled and defined as a position measuring ratio (%)=(distance effectively run by a GPS position measurement)×100/(run distance). |
