Information processing device, positioning method, and recording medium

A positioning method for an information processing device, the method comprising:

• acquiring, based on positioning signals for a position process received by a receiver carried by a subject from navigation satellites, actual ephemerides that are actual orbital information on the navigation satellites;
• acquiring predicted ephemerides that are predicted orbital information on the navigation satellites and having a predefined expiration time;
• determining whether a remaining period until the expiration time is a determination period or shorter, the determination period being set to at least a maximum term during which the subject is expected to be in a certain state;
• and
• executing an actual ephemeris acquiring operation that is based on the positioning signals received by the receiver when determination is made that the remaining period until the expiration time is the determination period or shorter, and determining a position of the subject based on the actual ephemerides acquired through the actual ephemeris acquiring operation.

A non-transitory computer-readable recording medium storing a program causing a computer to:

• acquire, based on positioning signals for a position process received by a receiver carried by a subject from navigation satellites, actual ephemerides that are actual orbital information on the navigation satellites;
• acquire predicted ephemerides that are predicted orbital information on the navigation satellites and have a predefined expiration time;
• determine whether a remaining period until the expiration time is a determination period or shorter, the determination period being set to at least a maximum term during which the subject is expected to be in a certain state;
• and
• execute an actual ephemeris acquiring operation that is based on the positioning signals received by the receiver when determination is made that the remaining period until the expiration time is the determination period or shorter, and determine a position of the subject based on the actual ephemerides acquired through the actual ephemeris acquiring operation.