Satellite positioning apparatus and train control system capable of determining accurate and limited position range of moving object

Abstract

A moving path memory stores a moving path of a train in advance. A signal receiver receives satellite positioning signals. A position calculator calculates measured positions and receiver clock errors, based on the satellite positioning signals and the moving path. A error area calculator sets vector pairs, each consisting of arbitrary two vectors perpendicular to each other on a plane spanned by a tangent vector and a radial vector of a tangent circle of the moving path at the measured positions, and calculates an error area for each vector pair, based on the measured positions, the receiver clock errors, and positions of positioning satellites. A position range extractor extracts a part of the moving path included in each error area, as a candidate position range corresponding to the error area. A position range restrictor determines a common area of the candidate position ranges, as a position range of the train.