How Does GPS Technology Work?

GPS or Global Positioning System is a satellite-based navigation system. This system, also known officially by the U.S. Dept. of Defense name NAVSTAR, was originally intended for the military, but was made available to the public in the 1980's.

How It Works

There are always at least 24 operational GPS satellites in orbit at all times, each with a 12 hour orbit. The satellites are powered by solar energy and have small rocket boosters to keep their orbit stable. All the satellites are synchronized so that repeating signals are transmitted at the same time. Each satellite transmits a radio signal that contains its location and the exact time, thanks to an atomic clock inside each one.

The receiver knows how far away a satellite is by how long it takes the signal to reach it. It compares the time the signal was transmitted with the time it was received. By receiving signals from at least four satellites, the receiver is able to calculate its position in three dimensions.

Imagine each satellite at the center of a sphere, with the receiver located somewhere on the surface of that sphere. The exact location of the receiver is at the point where the spheres of several satellites intersect.

How Accurate Is It?

Hand-held receivers such as those made by TomTom and Garmin are quite accurate, to within 10 to 20 meters. For greater accuracy, there are other receivers that use DGPS, or Differential Global Positioning System that requires an additional, fixed receiver. Observations made by the fixed unit are used to correct the position of the moving receiver.

GPS requires a clear "line of sight" between the satellite and the receiver. The signal will go through plastic, glass, and clouds, but will not pass through mountains, concrete, or steel. Heavy forested areas may also hamper the signal.

Other Uses of GPS

When most people think of GPS, they think of a portable device that helps them calculate their routes. However, there are other uses of GPS technology:
Many newer automobiles come with GPS Anti-theft systems which can pinpoint the exact location of a car should they be stolen.Police, fire, and emergency service providers use GPS receivers to locate the vehicles nearest to an emergency.GPS in small aircraft can help plot the perimeter of a forest fire so firefighters can maximize their efforts.GPS technology is used extensively by surveying, mapping, and construction companies.GPS technology can be used to detect air quality as well as map holes in the ozone. It is used to track major oil spills to aid in cleanup efforts.Wildlife experts use GPS to track migrating herds and endangered species.Recreational uses of GPS technology such as Geocaching.

As you can see, the current applications of GPS technology are vast, and as the future approaches, more and more individuals will find that owning a GPS unit is an absolute necessity. From recreational uses to crime prevention to protecting our loved ones, GPS technology is destined to become a very important part of our daily lives