The Quasi-Zenith Satellite System (QZSS), often referred to as Michibiki, is a regional satellite navigation system centred on Japan. This system is designed to enhance the availability and accuracy of Global Positioning System (GPS) data, particularly in urban areas where buildings may obstruct signals from GPS satellites. The QZSS constellation consists of seven satellites, three of which are in highly inclined, slightly elliptical, geosynchronous orbits. These orbits ensure that at least one satellite is almost directly overhead of Japan and the Asia-Oceania regions at all times. The fourth satellite is in a geostationary orbit. The QZSS provides two services: the positioning service, which is free for anyone to use, and the sub-meter class augmentation service, which provides higher accuracy for a fee. The signals from QZSS are compatible with those from GPS, allowing receivers to use data from both systems simultaneously for more accurate positioning. In addition to positioning, QZSS also provides messaging services. The system can broadcast short messages to users in the coverage area, which can be used for disaster information and other public services. The QZSS is managed by the Japan Aerospace Exploration Agency (JAXA) and was fully operational as of November 2018.
