‘Masters of Space’ keep GPS constellation grounded and on time

GPS is made up of three parts: satellites, ground stations, and receivers. The satellites act like the stars in constellations — we know where they are supposed to be at any given time within a small range of error. The satellites broadcast their location to the ground stations, and the ground stations are able to detect and correct that error in future uploads to the satellites. When the satellite’s location is more accurately broadcasted to the receivers, the receivers can calculate a more accurate position. A receiver, like you might find in your smartphone or navigation system in a car, is constantly listening for a signal from these satellites. The receiver figures out how far away they are from the satellites in view. Once the receiver calculates its distance from four or more satellites, it knows exactly where you are within a few yards of your actual location. (Courtesy graphic)