QZSS (Quasi Zenith Satellite System) is a Japanese satellite navigation system operating from inclined, elliptical geosynchronous orbits to achieve optimal high-elevation visibility in urban canyons and mountainous areas. The navigation system objective is to broadcast GPS-interoperable and augmentation signals as well as original Japanese (QZSS) signals from a three-spacecraft constellation.

The navigation system objective is to broadcast GPS-interoperable and augmentation signals as well as original Japanese (QZSS) signals from a three-spacecraft constellation in inclined, elliptical geosynchronous orbits.

Phase one will demonstrate the technological validation for the enhancement of GPS availability and performance and their application, using the first Quasi-Zenith Satellite (QZS 1) Michibiki. After evaluating these results, the plan moves into phase two which demonstrates the full system capability using three Quasi-Zenith Satellites, including QZS-1. JAXA is in charge of integrating the system as a whole, as well as cooperating with related research organizations to develop the High Accuracy Positioning Experiment System, the QZS Bus System and the Tracking Control System.