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GGG

Galileo - Europe's satellite navigation system.

GANS - Global Access, Navigation, and Safety - A United States Air Force program that is a potential vehicle for collaboration. GANS is an umbrella avionics program that integrates GPS, navigation and safety equipment, Navigation Warfare (NAVWAR), avionics modernization, military ground-based infrastructure, Global Air Traffic Management (GATM), and the Joint Precision Approach and Landing System (JPALS).

GDOP - See Geometric Dilution of Precision

geocaching - A high-tech treasure hunt using GPS to find hidden caches.

geocoding - See geotagging.

geodashing - An outdoor sport in which players use GPS receivers on a playing field that covers the entire planet. The waypoints, or dashpoints, to be reached are randomly selected. The win goes to the team that reaches the most dashpoints in a given time.

geodesy - The science related to the determination of the size and shape of the Earth by direct measurements.

geodetic - Of, pertaining to, determined, or effected by geodesy.

geodetic datum - A mathematic model designed to best fit part or all of the geoid.

geodetic height - The distance of a point above an ellipsoidal surface. The difference between a point's geodetic height and its orthometric height equals the geoidal height.

geofence - An imaginary boundary set which contains a GPS device - if that GPS device exceeds the boundary, an alarm is activated.

geoid - The hypothetical surface of the earth that coincides with sea level everywhere.

geomatics - The science and technology of gathering, analyzing, interpreting, distributing, and using geographic information.

Geometric Dilution of Precision - Since a GPS receiver determines position by triangulation, when the GPS satellites that are being received are clustered too close together, the positional accuracy determined by the receiver is diluted. The wider the angle between satellites, the better the measurement.

geostatic - see geostationary

geostationary - A satellite in a position always fixed to a relative point on the earth.

geotagging - The process of adding geographical identification metadata to various media such as websites, RSS feeds or images. This data usually consists of latitude and longitude coordinates, though it can also include altitude and placenames.

geosynchronous - see geostationary

GIS - Geographic Information System - A system of hardware and software used for storage, retrieval, mapping, and analysis of geographic data.

Globalstar - A handheld satellite phone service.

GLONASS - Global Orbiting Navigation Satellite System - See GNSS.

GNIS - Geographic Names Information System - Developed by the USGS in cooperation with the U.S. Board on Geographic Names (BGN). It contains information about almost 2 million physical and cultural geographic features in the United States.

gnomnoic projection - The gnomonic map projection displays great circles as straight lines.

GNSS - Global Navigation Satellite System - A Soviet space-based navigation system comparable to the American GPS system.

goto - A function on most GPS receivers that, when enabled, guides the user to a specific location.

GPRS - General Packet Radio Service - technology that enables high-speed wireless Internet and other data communications for uses such as mobile phones and computers.

GPS (Global Positioning System) - A system of 24 satellites used to locate any point on the earth by triangulation and distance measuring.

GPS III - A new initiative by the U. S. government to upgrade the current GPS system, which includes replacing all current satellites.

GPX - GPS eXchange format is an XML schema designed for transferring GPS data between software applications. It can be used to describe waypoints, tracks, and routes.

graticule - A network of parallels and meridians on a map or chart.

great circle - A circle described by the intersection of the surface of the Earth with a plane passing through the center of the Earth. The shortest distance between two points on the surface of the Earth is a segment of a great circle. All longitudes are great circles; the only latitude that is a great circle is the equator.

grid - A pattern of regularly spaced horizontal and vertical lines forming square zones on a map used as a reference for establishing points.

GSM - Global System for Mobile communications - A world standard for digital cellular communications.