QZSS

QZSS, short for Quasi-Zenith Satellite System, is a Japanese regional satellite navigation system designed to augment GPS for Japan and the surrounding region. It aims to improve positioning, navigation, and timing services by providing better signal availability and integrity, especially in urban canyons and mountainous terrain.

Space segment: The system uses a small constellation of satellites placed in highly inclined geosynchronous orbits that bring at least one satellite close to zenith over much of Japan for much of the day. The satellites are known as QZS-1 through QZS-4, collectively referred to as Michibiki. The satellites broadcast navigation signals and augmentation data intended to work with GPS receivers.

Ground segment and services: A network of ground facilities monitors the constellation and distributes augmentation data to receivers. QZSS provides an open service that is compatible with GPS signals and an encrypted, licensed service for authorized users that offers higher integrity and reliability. The system is designed to function as a regional augmentation system, similar in purpose to SBAS.

Compatibility and impact: Receivers that support QZSS can improve accuracy and coverage in Japan, including in city centers and mountainous areas. The service supports existing GPS receivers and is intended to enhance emergency preparedness, transportation, and consumer navigation in the region.

Status: The QZSS is a national project led by Japan's government agencies and is actively deployed with multiple satellites in orbit and ongoing ground infrastructure development.