How the system works The GPS is used by the military to lock on to enemy targets, and can be used to pinpoint a user's position on the globe. Members of the 50th Space Wing located at Falcon Air Force Base, Colorado, run the system. With the proper equipment, users can receive these signals to calculate time, location and velocity. The signals are so accurate, time can be figured to within a millionth of a second, velocity within a fraction of a mile per hour and location to within a few feet. Receivers have been developed for use in aircraft, ships and land vehicles as well as for hand carrying.
Civilian users get a package that offers less accurate positioning.
The BBC is not responsible for the content of external internet sites.