Europe's satellite navigation system.
See Global Access, Navigation, and Safety
See Geometric Dilution of Precision
General Packet Radio Service (GPRS)
Technology that enables high-speed wireless internet and other data communications for uses such as mobile phones and computers. GPRS requires a GSM network and subscription. If you want to quickly send and receive email or surf the web from your PDA, you should consider using a device and service that supports GPRS. GPRS supports data transfer speeds of 56 to 114 Kbps. With General Packet Radio Service (GPRS) you can enjoy a continuous wireless connection to data networks and access your favourite information and entertainment services. GPRS technology allows mobile phones to be used for sending and receiving data over an Internet Protocol (IP)-based network. GPRS as such is a data bearer that enables wireless access to data networks like the Internet. The applications using GPRS are WAP, MMS, SMS, Java and the PC dial-up (for example, Internet and e-mail). GPRS allows the user faster call set-up, higher data speed, and an “always on” connection.
A high-tech version of hide-and-seek. Geocachers seek out hidden treasures utilizing GPS coordinates posted on the Internet by those hiding the cache.
An imaginary boundary set which contains a GPS device - if that GPS device exceeds the boundary, an alarm is activated.
Geographic Information System (GIS)
A system of hardware and software used for storage, retrieval, mapping, and analysis of geographic data.
Geographic Names Information System (GNIS)
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.
The science and technology of gathering, analyzing, interpreting, distributing, and using geographic information.
Geometric Dilution of Precision (GDOP)
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. See Dilution of Precision.
A specific orbit around where a satellite rotates around the earth at the same rotational speed as the earth. A satellite rotating in geosynchronous orbit appears to remain stationary when viewed from a point on or near the equator. It is also referred to as a geostationary orbit. GPS satellites are not geostationary. aka Geostatic, Geostationary
See Geographic Information System
Global Access, Navigation, and Safety (GANS)
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).
Global Positioning System (GPS)
A global navigation system based on 24 or more satellites orbiting the earth at an altitude of 12,000 statue miles and providing very precise, worldwide positioning and navigation information 24 hours a day. Also called the NAVSTAR system. For more information, see About GPS.
A handheld satellite phone service.
Global System for Mobile communications (GSM)
One of the leading digital cellular systems. GSM allows eight simultaneous calls on the same radio frequency. First introduced in 1991, by the end of 1997, GSM service was available in more than 100 countries and has become the de facto standard in Europe and Asia. GSM Services include: GPRS and SMS. Similar to PCS but not compatible.
aka GNSS - Global Navigation Satellite System
The Global Orbiting Navigational Satellite System; the Russian counterpart to the United States’ GPS system. It consists of a constellation of 24 satellites (though the number may vary due to difficulties in funding for the system) transmitting on a variety of frequencies in the ranges from 1597-1617MHz and 1240-1260MHz (each satellite transmits on two different L1 and L2 frequencies).GLONASS provides worldwide coverage, however, its accuracy performance is optimised for northern latitudes, where it is better than GPS's SPS (there being no "Selective Availability" on GLONASS satellites). GLONASS positions are referred to a different Datum to those of GPS, i.e. PZ90 rather than WGS84. Some GPS receivers use a combination of both NAVSTAR and GLONASS to provide enhanced capabilities.
See Greenwich Mean Time
See Geographic Names Information System
A function on most GPS receivers that, when enabled, guides the user from their current location to one specific destination.
See General Packet Radio Service
Specification that contains full technical details on how a GPS receiver must interface with the system.
Electronic equipment that passively receives GPS signal for processing. A receiver may be hand-held or permanently mounted on a vehicle.
GPS (System) Time
The time scale to which GPS signals are referenced. GPS Time derives from a composite clock consisting of all operational monitor station and satellite atomic clocks. It is steered over the long run to keep it within about 1 micro-second of UTC, as maintained by the Master Clock at the U.S. Naval Observatory, ignoring the UTC leap seconds. At the integer second level, GPS Time equalled UTC in 1980, but currently, due to the leap seconds that have been inserted into UTC, it is ahead of UTC by more than 10 seconds. The relationship between GPST and UTC is transmitted within the Navigation Message.
The number of elapsed weeks since the week beginning 6th January 1980. The week number sequentially increments at Saturday/Sunday midnight in GPS (system) Time.
Graffiti is a character recognition software that enables users to quickly input data into touchscreen units. Graffiti is closely related to the ASCII character set which allows users to learn the input system relatively easily.
Network of parallels and meridians on a map or chart.
A circle described by the intersection of the surface of the Earth with a plane passing through the centre 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.
Greenwich Mean Time (GMT)
The mean solar time for Greenwich, England, which is located on the Prime Meridian (zero longitude). Based on the rotation of the earth, GMT is used as the basis for calculating standard time throughout most of the world.
A pattern of regularly spaced horizontal and vertical lines forming square zones on a map used as a reference for establishing points. Common map grids include that defined by the UTM (Universal Transverse Mercator) projection.
The velocity you are travelling relative to a ground position. Typically measured in "knots" (nautical miles per hour), but may be expressed in km/hr or m/s.
A radio wave that travels along the earth’s surface.