global positioning system

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Global Positioning System:

see navigation satellitenavigation satellite,
artificial satellite designed expressly to aid the navigation of sea and air traffic. Early navigation satellites, from the Transit series launched in 1960 to the U.S. navy's Navigation Satellite System, relied on the Doppler shift.
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global positioning system


A satellite-based coordinate positioning tool and navigation system that can rapidly and accurately determine the latitude, longitude, and altitude of a point on or above the Earth's surface. It is based on a constellation of 24 satellites orbiting the Earth at a very high altitude and uses a form of triangulation based on the known positions and distances of three satellites relative to the surface of the Earth. First developed by the US Department of Defense to provide the military with a state-of-the-art positioning system, GPS receivers are now small enough and economical enough to be used by the general public. In meteorology and climatology, GPS receivers are increasingly used, for example, in radiosondes, and have experimentally been used in the measurement of integrated (total column) precipitable water vapor.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

Global Positioning System

[′glō·bəl pə′zish·niŋ ‚sis·təm]
A positioning or navigation system designed to use 24 satellites, each carrying atomic clocks, to provide a receiver anywhere on earth with extremely accurate measurements of its three-dimensional position, velocity, and time. Abbreviated GPS.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

global positioning system (GPS)

A satellite-based radio-positioning, navigation, and time-transfer system operated by the U.S. Department of Defense. The space segment of the system consists of a constellation of twenty-four satellites in six orbits inclined at 55° to the equator. Twenty-one of these satellites are active while the others remain in standby mode. The system provides highly accurate position and velocity information and precise time, on a continuous global basis, to an unlimited number of properly equipped users. The system is unaffected by weather and provides a worldwide common grid reference system. The GPS concept is predicated upon accurate and continuous knowledge of the spatial position of each satellite in the system with respect to time and distance from a transmitting satellite to the user. The GPS receiver automatically selects appropriate signals from the satellites in view and translates these into a three-dimensional position, velocity, and time. The system accuracy for civil users is normally 300 ft (100 m) horizontally. The constellation of satellites for a similar system operated by the Russian Federation is called GLONASS. See global navigation satellite system.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

Global Positioning System

(GPS) A system for determining postion on the Earth's surface by comparing radio signals from several satellites. When completed the system will consist of 24 satellites equipped with radio transmitters and atomic clocks.

Depending on your geographic location, the GPS receiver samples data from up to six satellites, it then calculates the time taken for each satellite signal to reach the GPS receiver, and from the difference in time of reception, determines your location.

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(1) (General Print Server) An IBM mainframe feature that lets TN3270 clients access LPD/LPR printers via the SNA/VTAM network. See TN3270 and VTAM.

(2) (Global Positioning System) A satellite-based radio navigation system run by the U.S. Department of Defense, officially known as NAVSTAR GPS (see also GLONASS, Galileo and Beidou). Originally created for the military, today, GPS receivers are built into all smartphones and millions of cars and trucks. See in-dash navigation, CarPlay, Android Auto and portable GPS.

GPS vs. the "Nav"
Technically, the GPS is the satellite system, whereas a "navigation" system or "nav" is the GPS receiver that picks up the signals. In practice, most people refer to their navs as their GPS.

Three or Four Signals Are Required
At least four satellites are on the horizon at all times, which is sufficient to compute the current latitude, longitude and elevation anywhere on earth to within 15 to 70 feet (see latitude). If only three signals are present due to interference, elevation cannot be derived. If fewer than three, the location cannot be computed unless the nav is built into the vehicle and interfaces with the speedometer (see in-dash navigation).

The Satellite System
In six different orbits approximately 12,500 miles above the earth, 24 medium-earth orbit (MEO) satellites circle the earth every 12 hours. They constantly transmit their current time based on atomic clocks and current location on two frequencies in the L-band (L1: 1575.2 MHz; L2: 1227.6 MHz). Most navs pick up L1, while more advanced receivers pick up both for greater accuracy.

The nav calculates the distance to the satellites by comparing the times the transmitted signals were sent with the times received. By knowing the precise locations of the satellites at any given moment, the nav computes the current coordinates using trilateration, a method similar to how ship captains navigated for centuries (see triangulation).

First Launched in 1978
In this decades-old system, satellites are periodically replaced. In addition, worldwide government and commercial monitoring networks use earth stations to improve accuracy; for example, enabling farm equipment to plant ultra-precise rows of crops (see GPS augmentation system). See social navigation, vehicle tracking, reality view, GPS augmentation system, mobile positioning, LORAN, MEO, GNSS, Galileo and geocaching.

An Early Car Nav
In 1996, Sony's NVX-F160 was one of the first vehicle navigation systems, and it was able to find the nearest restaurant and hotel. (Image courtesy of Sony Corporation.)

GPS in the Woods
Portable navigation works everywhere. The flat object pointing up is the antenna. See portable GPS.

Navigation App in a Laptop
The Delorme Street Atlas offers extensive details including satellites in range (#15 just lost signal), elevation (Elv), azimuth (Az) and signal-to-noise ratio (dB). NET means: N=navigation satellite, E=ephemeris data available and T=being tracked (yellow object on dashboard is the GPS antenna).

Navigation App in a Laptop
The Delorme Street Atlas offers extensive details including satellites in range (#15 just lost signal), elevation (Elv), azimuth (Az) and signal-to-noise ratio (dB). NET means: N=navigation satellite, E=ephemeris data available and T=being tracked (yellow object on dashboard is the GPS antenna).

It Doesn't Get Better Than This
Tesla's navigation system is unlike any other. The 17" touchscreen displays more map area than any other nav screen.
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References in periodicals archive ?
The other closely related technological achievement mentioned earlier is GPS (Global Positioning System).
New Delhi [India], Jan 18 ( ANI ): The government has made it mandatory to have Global Positioning System (GPS) devices in passenger transport vehicles including taxis and buses from April 1.
The GPS III team is led by the Global Positioning Systems Directorate at the US Air Force Space and Missile Systems Centre.
Northrop Grumman and Raytheon are finalists for a contract to build the next-generation Global Positioning System ground-control station.
You'll never have to worry about getting lost on the way to your next appointment with global positioning system navigation, which plans routes and provides on-screen maps and voice directions.
It also comes with a global positioning system (GPS) option.
The US Air Force from Cape Canaveral Air Force Station, FL, successfully launched a Lockheed Martin-built Global Positioning System (GPS) satellite.
that keep a global positioning system device capable of telling you where you are (and where the enemy is, too).
VX-30 was responsible for the release of operational flight programs incorporating and integrating Navstar global positioning system navigation, APG-71 radar high-resolution mapping and the GBU-24 weapons system.
Applanix develops systems that integrate Inertial Navigation Systems (INS) and Global Positioning System (GPS) technologies.
TELECOMWORLDWIRE-9 June 2003-European global positioning system to be completed in 2004(C)1994-2003 M2 COMMUNICATIONS LTD
While the Global Positioning System (GPS) provides that functionality in an outdoor environment where one has line-of-sight (LOS) communication with GPS satellites, other solutions are needed for the much harder indoor localization problem.

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