Positioning satellite selection device, positioning information transmitting device, and positioning system

A positioning system comprising:

• a positioning information transmitting device comprising:
• one or more computation processors configured to operate as:
• a positioning data acquisition unit to acquire positioning data from a reference station which acquires from a plurality of positioning satellites the positioning data including respective range observation values and navigation information of each respective positioning satellite;
• a satellite position calculation unit to calculate respective satellite positions at each time of the respective positioning satellites from the navigation information included in the positioning data;
• a correction data generation unit to generate correction data for correcting an error included in the positioning data of the positioning satellites;
• a quality evaluation unit to obtain a quality evaluation value by evaluating quality of the correction data;
• a shortest time designation unit to set a shortest selection time which is a shortest time during which the positioning satellites are selected consecutively in time to a larger value as the quality evaluation value is poorer;
• a plan creation unit to allocate a minimum number of positioning satellites for a selection combination of the positioning satellites, and to obtain the selection combination at each time of the positioning satellites to be used for positioning on conditions (1) and (2) of selecting for longer than the shortest selection time of the positioning satellite, by using, as an evaluation criterion, a precision degradation index obtained from a geometric arrangement in the sky at each time calculated from the satellite positions of the minimum number of the positioning satellites, (1) select and add an unselected positioning satellite that will best enhance the precision degradation index to the selection combination a time at which a number of selected satellites is less than an upper limit and the precision degradation index is poorest, and (2) if the unselected positioning satellite is determined by the positioning data acquisition unit to be visible at one of neighboring times before and after the time, further select the unselected positioning satellite for longer than the shortest selection time to be part of the selection combination;
• and
• a correction data output unit to output the positioning satellites included in the selection combination at each time and the correction data for these positioning satellites;
• the positioning information transmitting device outputting the positioning satellites included in the selection combination at each time of the positioning satellites and correction data for correcting an error included in the positioning data of the positioning satellites;
• and
• a positioning terminal including a correction data acquisition unit to acquire from the positioning information transmitting device the positioning satellites included in a selection combination at each time of the positioning satellites, and correction data for correcting an error included in positioning data of these positioning satellites;
• a terminal positioning data acquisition unit to acquire positioning data including range observation values of the positioning satellites in the selection combination at each time;
• and a positioning computation unit to calculate a position at each time by using corrected range observation values obtained by correcting the range observation values of the positioning satellites with the correction data of the positioning satellites acquired by the correction data acquisition unit.