GPS: How It All Started

On Feb. 22, 1978, a revolution in navigation technology began with the launching of the first Block I Navstar GPS satellite from Vandenberg Air Force Base in California. Declared fully operational in 1995, the U.S. Global Positioning System consists of 24 satellites and five ground stations providing 24-hour instantaneous, precise, and continuous three-dimensional navigation data via one-way wireless communications to properly equipped military and civilian users, in any weather conditions, anywhere in the world. Six GPS satellites (known as "birds") are above the horizon at any given time, at any location on the planet. A GPS device need only receive signals from three birds to calculate time, location (latitude, longitude and altitude), direction of travel, and velocity. The signals are precise enough to calculate time to an accuracy of less than a millionth of a second, velocity within a fraction of a mile-per-hour, and location to within feet. (The more precise GPS receivers used in surveying can calculate the location to within centimeters.) The Global Positioning System was originally designed to provide accurate navigation data to military users, but continues to expand into the civilian area. GPS is used aboard private and commercial aircraft, ships and boats, and trucks and automobiles. GPS systems are used in search and rescue operations, detailed mapping projects, geodetic surveys, and more.

GPS solutions originally cost thousands of dollars, but as with any technology, prices have come down over the last few years. GPS solutions have been available for handheld computers since before the introduction of the first Windows Powered Handheld PCs in 1997. The series of articles in this section looks at a number GPS solutions for the Pocket PC and one stand-alone GPS solution. Special thanks go to the various GPS solution providers as well as authors Shawna Kelly, Ed Zabrek, Gary Garland, and Diane Dumas. Regular contributor Scott Hibbs has an interesting user profile on page 80, describing how he uses a Pocket PC equipped with GPS and other technology to help him fly his Piper Cub.