Terrestrial satellite navigation reinforcement system and availability prediction method

摘要

In order to improve the availability of a ground type satellite navigation reinforcement system, the present invention is provided with: a worst case ionospheric delay amount difference calculation unit which calculates a worst case ionospheric delay amount difference table for a ground system and an onboard system; a differential correction value calculation unit which creates usable satellite information; a geometric screening unit which guarantees that an error experienced by the onboard system will not exceed a protection level, regardless of which satellite set of positioning satellites is used by the onboard system; an availability prediction unit which creates availability loss information if the protection level when all usable satellites are used exceeds an alert limit; and an eliminated satellite determination unit which eliminates a prescribed number of positioning satellites from the positioning satellites included in the usable satellite information to calculate an eliminated satellite indicator, excludes from the positioning satellites included in the usable satellite information the positioning satellite which was eliminated when the eliminated satellite indicator was minimized, and using the result therefrom as usable satellite update information, causes the geometric screening unit to calculate an integrity parameter.