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GPS - the Global Positioning System - is a
navigation revolution. It’s a technology that pinpoints a
user’s location anywhere in the world, 24 hours a day,
regardless of the weather.
Designed by the United States’ Department of Defense
for use by the military, the GPS System was made
available to civilians for use in aviation, marine surveying
and general outdoor/recreation markets. Today, millions
of people utilize the accuracy and convenience of this
amazing technology to hunt, fi sh, hike, fl y, cruise and sail.
GPS consists of a constellation of 24 satellites orbiting
some 12,000 miles above the earth.
These satellites transmit signals containing time and
orbital data to calculate satellite position and almanac
data. Meanwhile, receivers used on the ground, sea and
air search the sky for the satellites. The GPS unit needs
to acquire good signals from at least three satellites to
determine a position on the surface of the earth. A fourth
signal is required to get three-dimensional positioning
which determines elevation or altitude.
Appendices
Appendix B
What is GPS?
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