GNSS vs GPS — what's the difference?

“GPS” and “GNSS” are easily confused, but the relationship is simple. GPS is the “name” of one US system, and GNSS is the “umbrella term” for all of them. We call phone location “GPS” because GPS is the most famous — but in reality several countries' systems are used together.

GPS = one US system

GPS (Global Positioning System) is the proper name of the satellite positioning system operated by the United States. Because it was the first to spread widely, it came to be used as a synonym for satellite positioning itself.

GNSS = the umbrella term for all satellite positioning systems

GNSS (Global Navigation Satellite System) is the umbrella term and includes: GPS (US), GLONASS (Russia), Galileo (Europe), BeiDou (China), QZSS / Michibiki (Japan, regional) and NavIC (India, regional). In other words, “GNSS = the set of the world's positioning satellites, including GPS”.

Why using several constellations is good

The more satellites you can use, the more stable your position stays even in urban canyons and mountains, raising both accuracy and availability — because with more satellites overhead, enough remain even when some signals are blocked. In RTK too, the more constellations you can use, the easier it is to get a high-accuracy “Fix”.

The special role of QZSS (Michibiki)

Japan's QZSS (Michibiki) flies an orbit that stays high above Japan for long periods, so it appears at a high elevation angle even in cities. It also broadcasts augmentation called CLAS and MADOCA, enabling cm-level positioning with a compatible receiver.

Today's receivers are “multi-GNSS” as standard

Recent receivers such as the u-blox F9P support multiple constellations and multiple frequencies. KUON's station richness score also awards points for the number of supported constellations.