Satellite navigation
A satellite navigation or satnav system is a way of pinpointing position very exactly.
Satnav uses a system of satellites. The system gives exact positioning. It allows small electronic receivers to find their position (longitude, latitude, and altitude/elevation). The position is given within a few metres using time signals transmitted along a straight line (line of sight) by radio from satellites. The signals also allow the receivers to calculate the current local time to high precision. A satellite navigation system with global coverage may be called a global navigation satellite system (GNSS). Global Positioning System is the biggest and most used GNSS. GLONASS, owned by Russia, is the second biggest. China, India, and the European Union are working on similar systems of their own.
The U.S. Space Force's Global Positioning System was the first global satellite navigation system and the first to be provided as a free global service.
Accuracy of Navigation Systems
GNSS satellites used for navigation on a smartphone in 2021
Launched GNSS satellites 1978 to 2014
