Overview
GPS satellites have been freely accessible to the world through the "public good" policy of the United States Air Force and their NAVSTAR Global Position System (GPS.) It is a system of satellites that broadcast a specific radio signal to be read by a receiver like this one. If three or more of the NAVSTAR satellites are in transmission range of the GPS unit, through simple mathematical calculations based on the distances between each orbiting satellite and the receiver, a 3-dimensional position on the X/Y/Z axes is determined. This in turn translates into latitude, longitude and altitude co-ordinates on a GPS receiver.