2. What is GPS

The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations.

GPS uses these satellites as reference points to calculate positions accurate to a matter of meters. In fact, with advanced forms of GPS you can make measurements to better than a centimetre!

In a sense it's like giving every square meter on the planet a unique address.

GPS receivers can now be put into a tiny space thanks to advanced electronics, so you will see them turning up in personal devices such as mobile phones.

These days GPS is finding its way into cars, boats, planes, construction equipment, movie making gear, farm machinery, laptop computers and even mobile phones.

GPS is becoming almost as basic a service as the telephone. You take it for granted that "GPS" lets you find your way around. A common technology that uses GPS is "Sat Nav" in cars.