|What Is GPS?
The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. 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. There are no subscription fees or setup charges to use GPS.
How it works
GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to
earth. GPS receivers take this information and use triangulation to calculate the user's exact
location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was
received. The time difference tells the GPS receiver how far away the satellite
is. Now, with distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic
A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D position
(latitude and longitude) and track movement. With four or more satellites in
view, the receiver can determine the user's 3D position (latitude, longitude and
altitude). Once the user's position has been determined, the GPS unit can calculate other
information, such as speed, bearing, track, trip distance, distance to
destination, sunrise and sunset time and more.