Consideration on Positioning Accuracy of the System for Geostationary Augmentation to GPS

Abstract

The International Civil Aviation Organization (ICAO) investigates the Global Navigation Satellite System (GNSS) as a new navigation system in civil aviation. In GNSS, the position and time can be determined globally using satellites. The Global Positioning System (GPS) of the United States is considered as one of candidates for the GNSS. It is pointed out that GPS has some faults if this system is adopted as the GNSS. One of these faults is deterioration of positioning accuracy. The ICAO suggests those faults of GPS should be improved if GPS is used as the GNSS.

The system for Geostationary Augmentation of GPS is considered as one of means to resolve the faults of GPS. A geostationary satellite is addid to GPS in the System for Geostationary Augmentation of GPS. A GPS-like signal is generated at a ground station and transmitted to users via the geostationary satelite. Users can use this GPS-like signal in positioning calculation. The use of GPS-like signal in positioning calculation is expected to improve positioning accuracy which is obtained when only GPS satellites are used.

This improvement of positioning accuracy in the System for Geostationary Augmentation of GPS is cofirmed in this report by a computer simulation.

Especially, it is found the use of all satellites in view is very effective in the calculation of dilution of precision (DOP) and a user position.