What is QZSS?
QZSS (Quasi-Zenith Satellite System) is Japan’s regional satellite navigation system designed to enhance GNSS performance over Japan and the Asia-Pacific region. The QZSS constellation currently consists of four satellites: three in inclined geosynchronous orbits (QZO) and one in geostationary orbit (GEO), with plans for expansion. The unique orbital configuration ensures that at least one QZSS satellite is always near zenith over Japan, improving signal availability in urban canyons and mountainous areas where traditional GNSS signals may be blocked.
QZSS provides several services:
- PNT (Positioning, Navigation, and Timing): Standard GNSS signals compatible with GPS.
- SLAS (Sub-meter Level Augmentation Service): Delivers sub-meter accuracy corrections.
- CLAS (Centimeter Level Augmentation Service): Provides centimeter-level accuracy using PPP-RTK techniques via the L6 signal.
- MADOCA-PPP: A multi-GNSS advanced orbit and clock augmentation service for precise point positioning.
- Messaging Services: For disaster/crisis management and safety confirmation.
QZSS augments signals from multiple GNSS constellations (GPS, Galileo, GLONASS) and broadcasts correction data to improve accuracy, reliability, and integrity for users in its service area. It is widely used in applications requiring high precision, such as autonomous vehicles, surveying, and disaster response
