Patent ID: 8154447

Claim:
A position calculating method for positioning of a positioning device by a satellite signal from a satellite, the positioning device having a central processing unit (CPU), the position calculating method comprising: determining by the CPU a positioning satellite which is used for position calculation on the basis of at least reliability of satellite orbits in a prediction target period corresponding to a position calculation point, the reliability of satellite orbits being set in long-term predicted orbit data in which satellite orbits of positioning satellites and reliability of the satellite orbits are associated for each prediction target period; calculating by the CPU a position on the basis of a positioning signal received from the determined positioning satellite; and deciding by the CPU positioning satellites having equivalent reliability of the satellite orbit in the prediction target period corresponding to the position calculation point, the determining including determining, taking into account reliability of a satellite orbit in a prediction target period before or after the prediction target period corresponding to the position calculation point, whether the positioning satellites having equivalent reliability of the satellite orbit should be used for the position calculation.