Global Positioning System

The Global Positioning System (GPS) is a satellite navigation system that allows users to locate their approximate position on Earth. There are 27 satellites orbiting Earth, for use with GPS units. The satellites are positioned around Earth, and are constantly orbiting so that signals from at least three or four satellites can be picked up at any given moment by a GPS receiver.

To use GPS to find your location on Earth, you need a GPS receiver. The receiver calculates your approximate latitude and longitude — usually within 10 m — by processing the signals emitted by the satellites. If enough information is present, these satellites can also relay information about elevation, direction of movement, and speed. With signals from three satellites, a GPS receiver can calculate location on Earth without elevation, while four satellite signals will allow a GPS receiver to calculate elevation also. For more information on how the satellites are used to determine location.

Uses for GPS technology GPS technology is used extensively for navigation by airplanes and ships. However, as you will read later, it is also used to help detect earthquakes, create maps, and track wildlife. GPS technology also has many applications for everyday life. Some people now have GPS receivers in their cars to help navigate to preprogrammed destinations such as restaurants, hotels, and their homes. Hikers, bikers, and other travelers often have portable, handheld GPS systems with them at all times. This allows them to find their destinations more quickly and can help them determine their location so they do not get lost. Some cell phones also contain GPS systems that can help you find your location.

Global Positioning System

A global positioning system, or GPS, is a mechanism for specifying locations on the Earth using a cluster of satellites. Two systems are in use: one developed, managed, and maintained by the United States Department of Defense, and the other under the control of the Russian military called GLONASS. The European Union has had a separate GPS system known as Galileo in development for over a decade, but the system is not yet operational. Recent announcements (2008) from EU administrators indicate that the EU expects the system to be ready by 2013. The American system utilizes more than two dozen satellites in medium orbit, which broadcast high-energy signals to receivers on the surface of the planet, or in the lower atmosphere. The U.S. Department of Defense launched satellites throughout the late 1980s and early 1990s, building the capacity of the network toward global coverage. An early form of GPS technology was used by the U.S. military during the first GulfWar in 1990, but the system remained accessible only for military use. In 1993, the system reached full operating capacity, with 24 satellites in orbit. Three years later, the government passed legislation allowing for the civilian use of the system. The result was an explosion of the use of GPS technology because the applications were widespread, and relatively inexpensive GPS receivers were available to the general public in only a few years. By 2000 GPS-related business amounted to over $6 billion, and continued to increase throughout the early 2000s. The advantages of GPS technology are many. Access to the system is free, a GPS receiver will work outdoors in any weather (but typically will not work inside a building), and the system is accessible at all times.

The applications of GPS technology are virtually limitless. Inexpensive GPS receivers can pinpoint the user’s location within a few meters, and provide a map showing the location. In addition, the location can be stored, so that the user can return to virtually the exact same place in the future. More expensive GPS receivers can provide the location of the user, or an object being mapped, to within a few centimeters. GPS is a highly useful tool for outdoor recreation. Those engaged in hiking, fishing, and hunting can find their location if lost, record a favorite spot and the path to reach it, or even map an area using a GPS receiver. Business applications are also numerous. Law enforcement can track the movements of suspected criminals by attaching a GPS unit to a vehicle. Surveyors can use GPS to survey a piece of property much more quickly than when using older techniques. Farmers can use high-precision planting techniques that employ GPS technology, increasing yields and conserving costs of production. Aircraft can be precisely tracked by ground controllers using GPS, and the aircraft itself can use GPS for navigational purposes. There are also applications for forestry, wildlife management, and many other fields. Of course, perhaps the broadest application of GPS technology is to commercial mapping, which can now be done more quickly and more accurately.