noun
quasi-zenith satellite system; QZSS
Technical term for a Japanese satellite navigation system that augments GPS, with satellites in quasi-zenith orbits to improve coverage in urban and mountainous areas.
準天頂衛星システムは、GPSの精度を高めるために開発された。
The quasi-zenith satellite system was developed to improve GPS accuracy.
GPS is the global positioning system; QZSS is a regional augmentation system that works alongside GPS.
Compound of 準天頂 (quasi-zenith) + 衛星 (satellite) + システム (system). The term describes satellites in orbits that pass near the zenith over Japan.