What is GNSS (global navigation satellite system)?

Global Navigation Satellite Systems (GNSS) incorporate constellations of Earth-orbiting satellites which broadcast their locations in space, ground control stations, and receivers that estimate ground positions. The space segment depicts the GNSS constellations orbiting between 20,000 to 37,000 kilometres over the earth. These satellites broadcast signals that distinguish which satellite is communicating and its time, orbit and status or health.