The skies above us are teeming with satellites that form the Global Positioning System, better known as GPS. Here’s the Stuff Instant Expert guide to what they do.
1) The Global Positioning System went live in 1978 having been developed by the US. The Russian GLONASS system became operational in 1993, but has suffered mixed fortunes because of the unstable Russian political situation.
2) The 24 GPS satellites beam ultra-precise time signals back to Earth, which are picked up by the radio receivers in GPS systems and computed into an exact location. Originally this was of great use to the military, but now supports countless consumer applications.
3) Us non-military types most commonly use GPS for navigation, either by plane, boat, car, bike or foot. But, GPS is also used for advanced car alarms, fleet management and hobbies-cum-games such as Geocaching.
4) While the basic GPS is unchanged from the original, accuracy has been improved by systems such as Differential GPS and Wide Area Augmentation System for compatible receivers.
5) A new positioning system called Galileo (pictured) is being developed, primarily by European countries, and should go live in 2010. It promises greater accuracy, especially in built-up areas. The developers envisage that Galileo receivers will be built in to all sorts of consumer technology, leading to an abundance of location-based services.