GPS - Global Positioning System

The Global Positioning System (GPS) is a satellite navigation system, composed of twenty-four satellites 20,200 km (12,500 miles) above the earth. The satellites are spaced in such a way that at least six of them are in view to users anywhere in the world at any time. These satellites broadcast precise timing signals by radio to portable or handheld GPS receivers, allowing the receiver to determine its location accurately (longitude and latitude) along with its altitude, speed and the time.

GPS was developed in the 1970s by the United States Department of Defense and is officially titled NAVSTAR GPS (Navigation Signal Timing and Ranging GPS). The Department covers the $400 million annual cost of maintaining the system (including replacing aging satellites), and allows the system to be used free-of-charge across the world.

GPS Applications

Nowadays, Global Positioning System (GPS) devices can be found everywhere - they're used in cars, airplanes, boats, and even in mobile phones. Some of the most popular uses are listed below.

1. Military

GPS is used by the military for accurate targeting of missiles or 'smart bombs', along with improved command and control of forces through enhanced locational awareness.

2. Precise Time Recording

GPS can be used as a source of accurate time, such as a reference clock for time code generators or as NTP (Network Time Protocol) clocks.

3. Navigation

GPS is now used around the world as a navigation aid in cars, aeroplanes and ships, and hand-held GPS receivers have become very popular with hikers and other outdoor enthusiasts. Read on for more information about satellite navigation systems (Sat Nav) ...

4. Surveying

GPS receivers are used by land surveyors to locate boundaries and survey markers and are one of the essential tools in modern map-making.