A global
positioning systems (GPS) is a satellite
navigation system used to determine geographic locations.
GPS is funded by and
controlled by the U. S. Department of Defense (DOD).
While there are many thousands of civil users of GPS
world-wide, the system was designed for and is operated by the
U. S. military.
GPS provides specially
coded satellite signals that can be processed in a GPS
receiver, enabling the receiver to compute position, velocity
and time.
Four GPS
satellite signals are used to compute positions in
three dimensions and the time offset in the receiver clock.
The GPS User Segment
consists of the GPS receivers and the user community.
GPS receivers convert satellite signals into position,
velocity, and time estimates. Four satellites are required to
compute the four dimensions of X, Y, Z (position) and Time.
GPS receivers are used for navigation, positioning, time
dissemination, and other research.
