Introduction to Global Positioning System (GPS)
This page provides an introduction to Geographic Positioning System (GPS). Please click on the links below or scroll down the page for more information.
Table of Contents
Introduction to GPS
Introduction to GPS
The Global Positioning System (GPS) is a satellite-based navigation system that consists of 24 orbiting satellites, each of which makes two circuits around the Earth every 24 hours. These satellites transmit three bits of information – the satellite's number, its position in space, and the time the information is sent. These signals are picked up by the GPS receiver, which uses this information to calculate the distance between it and the GPS satellites.
With signals from three or more satellites, a GPS receiver can triangulate its location on the ground (i.e., longitude and latitude) from the known position of the satellites. With four or more satellites, a GPS receiver can determine a 3D position (i.e., latitude, longitude, and elevation). In addition, a GPS receiver can provide data on your speed and direction of travel. Anyone with a GPS receiver can access the system. Because GPS provides real-time, three-dimensional positioning, navigation, and timing 24 hours a day, 7 days a week, all over the world, it is used in numerous applications, including GIS data collection, surveying, and mapping.
All About GPS Tutorial
This tutorial is designed to give you a good basic understanding of the principles behind GPS without too much technical detail. This website requires the user to register to access its materials. Trimble accessed March 2004.
This website covers 1) the fundamental concepts of what makes GPS work, the basics of setting up the receiver, taking a position fix, and activating the GOTO navigation function to a given waypoint; 2) the concepts of the Latitude and Longitude Grid system and how to plot and read the coordinates of positions on a map; and 3) these same concepts using the Universal Transverse Mercator (UTM) metric grid system. Waypoint Enterprises, Inc. accessed March 2004.
GPS as a Car Accessory, LelandWest
A brief history of how GPS evolved to serve as an accessory to aid navigation of automobiles.
Global Positioning System (GIS Development)
Global Positioning System Overview (Geographer's Craft)