Global positioning system (GPS)

A GPS receiver uses signals from a set of US satellites to calculate its geographic location, and establish the reference time. GPS receivers are built into a wide variety of devices, including cell phones, navigation devices, vehicle tracking systems. Similar global systems have been established by the EU (Galileo), China (BeiDou) and Russia (Glonass), and regional systems by Japan (QZSS) and India (IRNSS); however GPS is more widely used.