1.Global Positioning System
Public information about the Global Positioning System (GPS) and other space-based positioning, navigation, and timing (PNT) systems
-- http://www.gps.gov/
3.Garmin
Designs, manufactures, and markets GPS navigation and communications equipment.
-- http://www.garmin.com/
4.Garmin: What is GPS?
The global positioning system is a satellite-based navigation system consisting of a network of 24 orbiting satellites, eleven thousand nautical miles in space, in ...
-- http://www.garmin.com/aboutGPS/