The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of about 18-24 satellites placed into orbit. GPS was originally intended for military applications, but in the late 1970s, the government made a system available for civilian use. GPS works in any weather conditions, anywhere in the world, 24/7. There are no cost for the use.

How it works

GPS satellites circle the earth twice a day in the same orbit and transmit signal information to down to mother earth. GPS take this information and use triangulation to calculate the user's exact location. 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 from the satellite it is. Now, with this distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic map.

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 also altitude). Once the user's position has been determined, the GPS unit can calculate other information, such as speed, track, trip distance, distance to destination, sunrise and sunset time and a lot more.

How accurate is GPS?

Today's GPS receivers are extremely accurate, thanks to parallel multi-channel design. Garmin's 12 parallel channel receivers are quick to lock onto satellites when first turned on and they maintain strong locks, even in dense foliage or urban settings with tall houses. Certain atmospheric factors and other sources of error can affect the accuracy of GPS receivers. Garmin