Real-time Simulation of QZSS Regional Satellite Navigation

QZSS (Quasi-Zenith Satellite System) is a Japanese satellite navigation program with a regional service coverage. The orbits for QZS (quasi-zenith satellite) are 24-hour elliptic orbit inclined 43 degrees in order to broadcast radio signals from high elevation angle into urban canyons. The first QZSS satellite, QZS-1 "Michibiki" was successfully launched in 2010 and the technical verification has been conducted by several organizations. The original concept of QZSS consists of three or more satellites on so-called Quasi-Zenith orbit and optional geostationary satellites, so as to enable satellite positioning independent of GPS. The performance of such a constellation would be limited in comparison with GPS, however, this will work as the national minimum backup regarding unexpected outage of GPS. In this paper, we confirm position accuracy achieved by candidate QZSS constellation with hardware GNSS receiver. To put it concretely, based on real-time simulation, we reveal not only DOP characteristic but the actual position accuracy achieved by candidate QZSS constellation. It was confirmed that the navigation by QZSS constellation can achieve horizontal accuracy of 10 m or better and vertical accuracy of 14 m or better when moderate user range error.