The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites that orbit the earth at approximately 12,000 miles above surface and make two complete orbits every 24 hours. Placed into orbit by the U.S. Department of Defense the GPS was originally intended for military applications, but in the 1980s, the government made the system available for civilian use. GPS works in any weather conditions, anywhere in the world, 24 hours a day.
Today, the use of GPS has extended to both the commercial and scientific worlds. Commercially, GPS is used as a navigational and positioning tool in airplanes, boats and cars. It can also be used for any outdoor activity such as canoeing, hiking, fishing and camping. GPS also plays an important role in the scientific community as it helps Meteorologists use it for weather forecasting and global climate studies. Geologists can also make use of GPS as a highly accurate method of surveying and can also use it to measure tectonic motions during and in between earthquakes.
The Global Positioning System is made up of three parts, satellites orbiting the Earth controlling and monitoring stations on Earth, GPS receivers owned by users and GPS satellites broadcasting signals from space which are picked up and identified by GPS receivers. Each GPS receiver then provides a three-dimensional location (latitude, longitude, and altitude) plus the time. The GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference will tell the GPS receiver how far away the satellite is. With distance measurements from a few more satellites the receiver will be enabled to pinpoint the location of the user and display it on the unit’s electronic map.
Once the user's position has been determined, the GPS unit can then calculate other information, such as speed, bearing, track, trip distance, distance to