“The most significant development for [navigation and surveillance] since... radio navigation."
National Aeronautical Association
The Global Positioning System (GPS) is a system of satellites that transmit microwaves over specific wavelengths. GPS receivers pick up signals from these satellites and define a location from the information they obtain. The system was developed by the U.S. government in 1993, but similar mechanisms have been set up in other countries including the Russian GLONASS (incomplete), China's-COMPASS system, and the upcoming Galileo system in 'Europe. The GPS system costs the U.S. government approximately $750 million a year and is used worldwide for navigation.
The system is extremely useful and there are a huge range of commercial and domestic applications.
In military terms, GPS is used to track targets, locate positions in unknown territory, and project missiles, and it is also used in search and rescue and reconnaissance missions. In the civilian world, GPS units are used for in-car navigation systems as well as on domestic seacraft. Today, many cell phones include internal GPS systems that allow for tracking and can be used to locate users over wide areas. GPS also brings improved accuracy to surveys of tectonic activity such as earthquakes and tremors.
