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GPS References

The Almanac: GPS, GLONASS, Galileo, and satellite-based augmentation systems (SBAS) constellation data and information sources.
GPS/GNSS Acronyms
GPS/GNSS Glossary
How Does GPS Work?: Brief overview by GPS World "Innovation" columnist Richard Langley.
GPS World Innovation: The Early Years: Hard-to-find reprints of the first 15 "Innovation" columns, from January 1990 to October 1991, are available here as downloadable PDFs.
GPS History, Chronology, and Budgets (Downloadable PDF)
Receivers vs. Tracking
Timeline of GPS Development

Other GPS and GNSS Sites

Note: GPS World does not recommend specific GPS equipment or manufacturers. If you have questions about particular models, you should contact the manufacturer or a local distributor/retailer.

GPS World publishes:

GPS Receiver Survey (January issue, print only, no website posting)
GPS Antenna Survey (February, print only, no website posting)
Buyers Guide (June issue)
Product Showcase

To order back issues of the magazine, please contact us.

Receivers versus Tracking

There is a popular misperception that GPS is a "tracking" technology and therefore that it can be easily misused by public agencies and private companies to monitor people's whereabouts.

In reality, a GPS receiver is just that, a receiver. It knows its location (latitude, longitude, altitude, compass heading, and speed) anywhere on Earth, within about 30 feet. (Differential GPS receivers can achieve an accuracy of a few millimeters.)

However, several companies now produce GPS-based tracking devices that couple a GPS receiver with a wireless transmitter, usually using the control channel on a cellular network. These devices relay the position of a vehicle to a tracking center.

Someone who purchases a handheld GPS receiver at a sporting goods store or a car GPS receiver at an electronics store need not fear that Big Brother will hence always know her or his whereabouts. However, someone renting a car or a boat might ask whether the vehicle is equipped with a GPS receiver and a transmitter, as rental companies often track their vehicles.

Basic Timeline of GPS Development

Late 1960s: The GPS concept is developed.
Early 1970s: The GPS program funded and Joint Program Office within the Department of Defense is established.
December 1973: The proposal for a Global Positioning System is approved by the Defense System Acquisition and Review Council (DSARC).
Mid-1970s: Ground testing is conducted.
February 22, 1978: The first GPS satellite is launched.
1986-1989: The GPS program is put on hiatus following the Challenger space shuttle disaster.
1989: The launch program is revived, with changes in the design of the satellite constellation.
1989: The Magellan Corporation introduces the first handheld GPS receiver.
January 1990: The first issue of GPS World is published.
1991: A major glitch that slowed progress is detected and fixed.
January 1991: GPS is used in Operation Desert Storm.
December 1993: Declaration of Initial Operational Capability (IOC) is made by the U.S. Secretary of Defense.
May 2, 2000: Selective Availability is turned off by presidential directive; inexpensive civilian GPS receivers increase their horizontal accuracy from "no worse than" 100 meters to 15-25 meters.