GPS - Global Positioning System

GPS is the shortened form of NAVSTAR GPS. This is an acronym for NAVigation System with Time And Ranging Global Positioning System. GPS is a solution for one of man's longest and most troublesome problems. It provides an answer to the question 'Where on earth am I ?'
One can imagine that this is an easy question to answer. You can easily locate yourself by looking at objects that surround you and position yourself relative to them. But what if you have no objects around you ? What if you are in the middle of the desert or in the middle of the ocean ? For many centuries, this problem was solved by using the sun and stars to navigate. Also, on land, surveyors and explorers used familiar reference points from which to base their measurements or find their way. These methods worked well within certain boundaries. Sun and stars cannot be seen when it is cloudy. Also, even with the most precise measurements position cannot be determined very accurately.

At the beginning of the 1970s, a new project was proposed - GPS. This concept promised to fulfill all the requirements of the US government, namely that one should be able to determine ones position accurately, at any point on the earth's surface, at any time, in any weather conditions.
GPS is a satellite-based system that uses a constellation of 24 satellites to give a user an accurate position.

Excerpted from GPS Basics Introduction to GPS by Leica Geosystems Inc.

"A system of satellites and receiving devices used to compute positions on the Earth. GPS is used in navigation, and its precision supports cadastral surveying".

Excerpted from Glossary of GIS Terms in www.esri.com Copyright © 1995-2003 ESRI