The Global Positioning System (GPS) is a satellite based system that gives real time three
dimensional (3D) latitude, longitude, and height information at sub-meter accuracy. The system
was developed by the United States military in the late 1970’s to give troops accurate position
and navigational information. A GPS receiver calculates its position on earth from radio signals
broadcast by satellites orbiting the earth. There are currently twenty-four GPS satellites in this
system.