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Article: GPS (Global Positioning System)
- Article from:
- World of Earth Science
CopyrightCOPYRIGHT 2003 The Gale Group, Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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GPS (global positioning system)
Long before the
space
age, people used the heavens for navigation. Besides relying on the
Sun
,
Moon
, and stars, the early travelers invented the magnetic compass, the sextant, and the seagoing chronometer. Eventually, radio navigation in which a position could be determined by receiving radio signals broadcast from multiple transmitters came into existence. Improved high frequency signals gave greater accuracy of position, but they were blocked by mountains and could not bend over the horizon. This limitation was overcome by moving the transmitters into space on Earth-orbiting satellites, where high frequency signals could accurately cover wide ...