| Term |
Definition |
Geocaching |
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. |
Geodetic Datum |
A math model representing the size and shape of the earth (or a portion of it). |
Geographic Information System (GIS) |
A computer system or software capable of assembling |
Geosynchronous Orbit |
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. |
GIS |
See Geographic Information System. |
Global Positioning System (GPS) |
A global navigation system based on 24 or more satellites orbiting the earth at an altitude of 12 |
Glonass |
The Global Orbiting Navigational Satellite System; the Russian counterpart to the United States’ GPS system. |
GMT |
See Greenwich Mean Time. |
GoTo |
A route consisting of one leg |
GPS |
See Global Positioning System. |
Greenwich Mean Time (GMT) |
The mean solar time for Greenwich |
Grid |
A pattern of regularly spaced horizontal and vertical lines forming square zones on a map used as a reference for establishing points. Grid examples are UTM |
Heading |
The direction in which a vehicle is moving. For air and sea operations |
Healthy |
A term used when an orbiting GPS satellite is suitable for use. "State" is also used to refer to satellite health. |
Initialization |
The first time a GPS receiver orients itself to its current location and collects almanac data. After initialization has occurred |
Input/Output (I/O) |
The two-way transfer of GPS information with another device |
Internal unit ID |
Security number found in the menu options of a GPS. |
Invert Route |
To display and navigate a route from end to beginning for purposes of returning to the route's starting point. |
Ionosphere |
A region of the earth's atmosphere where ionization caused by incoming solar radiation affects the transmission of GPS radio waves. It extends from a height of 50 kilometers (30 miles) to 400 kilometers (250 miles) above the surface. |
L Band |
The radio frequencies that extend from 390 MHz to 1550 MHz. The GPS carrier frequencies are in the L band (1227.6 MHz and 1575.42 MHz). |
L1 Frequency |
One of the two radio frequencies transmitted by the GPS satellites. This frequency carries the Coarse Acquisition Code (C/A code) |
L2 Frequency |
One of the two radio frequencies transmitted by the GPS satellites. This frequency carries only the P-Code |
LAAS |
See Local Area Augmentation System. |
Latitude |
A position's distance north or south of the equator |
LCD |
See Liquid Crystal Display. |
Leg (Route) |
A portion of a route consisting of a starting (from) waypoint and a destination (to) waypoint. A route that is comprised of waypoints A |
Line Of Sight (LOS) Propagation |
Of an electromagnetic wave |
Liquid Crystal Display (LCD) |
A display circuit characterized by a liquid crystal element sandwiched between two glass panels. Characters are produced by applying an electric field to liquid crystal molecules and arranging them to act as light filters. |
Lithium Battery |
A soft |
Local Area Augmentation System (LAAS) |
The implementation of ground-based DGPS to support aircraft landings in a local area (20-mile range). |
Longitude |
The distance east or west of the prime meridian (measured in degrees). The prime meridian runs from the north to south pole through Greenwich |
LORAN |
Loran |
Magnetic North |
Represents the direction of the north magnetic pole from the observer's position. The direction a compass points. |
Magnetic Variation |
In navigation |
Map Display |
A graphic representation of a geographic area and its features. |
MapSource |
Application on the desktop that allows you to view the maps and apply the maps. |
Mean Sea Level |
The average level of the ocean's surface |
MOB |
Man over board. |
Multimedia card (MmC card) |
Smaller version of a sd card. |
Multipath Error |
An error caused when a satellite signal reaches the GPS receiver antenna by more than one path. Usually caused by one or more paths being bounced or reflected. The TV equivalent of multipath is "ghosting." |
Multiplexing Receiver |
A GPS receiver that switches at a very rapid rate between satellites being tracked. Typically |
