Patent attributes
A processor determines whether the remaining period until the expiration time of predicted ephemerides, which are predicted orbital information on navigation satellites, is a determination period or shorter. The determination period is set to at least the maximum term during which a subject is expected to be in a certain state. The processor causes an operation of acquiring actual ephemerides, which are actual orbital information on the navigation satellites, to be executed based on the positioning signals received when determination is made that the remaining period until the expiration time of the predicted ephemerides is the determination period or shorter, and determines the position of the subject based on the actual ephemerides acquired through the actual ephemeris acquiring operation.
