The Global
Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). The GPS uses a constellation of between 24 and 32 Medium Earth Orbit
satellites that transmit precise microwave signals, that enable GPS receivers to
determine their current location, the time, and their velocity (including
direction). GPS was developed by the United States Department of Defense. Its
official name is NAVSTAR-GPS. Although NAVSTAR-GPS is not an acronym, a
few acronyms have been created for it. The GPS satellite constellation is
managed by the United States Air Force 50th Space Wing.
