GPS - Global Positioning System
Short for Global Positioning System, a worldwide MEOsatellite navigational system formed by 24 satellites orbiting the earth and their corresponding receivers on the earth. The satellites orbit the earth at approximately 12,000 miles above the surface and make two complete orbits every 24 hours. The GPS satellites continuously transmit digital radio signals that contain data on the satellites location and the exact time to the earth-bound receivers. The satellites are equipped with atomic clocks that are precise to within a billionth of a second. Based on this information the receivers know how long it takes for the signal to reach the receiver on earth. As each signal travels at the speed of light, the longer it takes the receiver to get the signal, the farther away the satellite is. By knowing how far away a satellite is, the receiver knows that it is located somewhere on the surface of an imaginary sphere centered at the satellite. By using three satellites, GPS can calculate the longitude and latitude of the receiver based on where the three spheres intersect. By using four satellites, GPS can also determine altitude.
GPS was developed and is operated by the U.S. Department of Defense. It was originally called NAVSTAR (Navigation System with Timing and Ranging). Before its civilian applications, GPS was used to provide all-weather round-the-clock navigation capabilities for military ground, sea, and air forces.
GPS has applications beyond navigation and location determination. GPS can be used for cartography, forestry, mineral exploration, wildlife habitation management, monitoring the movement of people and things and bringing precise timing to the world.
Perceptual computing is the ability for a computer to recognize what is going on around it. More specifically, the computer can perceive the... Read More »Apple Pay Promises to Strengthen Payment Security
Experts believe that Apple Pay and other competitive payment systems will be far more secure than cards, even cards equipped with EMV chips. Read More »The Great Data Storage Debate: Is Tape Dead?
Tape clearly is on the decline. But remember, legacy systems can hang for a shockingly long time. Read More »
A network is a group of two or more computer systems or devices, linked together to share resources, exchange files and electronic communications.... Read More »Computer Architecture Study Guide
This Webopedia study guide describes the different parts of a computer system and their relations. Read More »Webopedia Polls
The trend for the past two years has been for shoppers to spend more online during the holiday season. How do you typically shop for holiday... Read More »
Stay up to date on the latest developments in Internet terminology with a free weekly newsletter from Webopedia. Join to subscribe now.
- Watch Datamation's editor James Maguire moderate roundtable discussions with tech experts from companies such as Accenture, Dell, Blue Jeans Network, Microsoft and more »