bench mark - A material object, natural or man-made, with a known elevation or horizontal location. Bench marks can be used as reference points when traveling a route or in determining the elevation of nearby land features.
bitmap image - An image with 1 bit of color information per pixel, also known as a bitmapped image.
Bluetooth - A standard of radio technology that makes it possible to transmit signals over short distances between telephones, computers and other devices.
BTGPS - Bluetooth GPS - See Bluetooth.
cartography - The art or technique of making maps or charts.
CF - See compact flash.
clinometer - A device, usually similar to a compass, used to measure vertical angles, as in the slope of a hill.
collar - The area surrounding the actual map itself containing necessary information such as scale, legend, latitude and longitude, etc.
compact flash - (CF) A standard that PDAs, laptops, and other computer-related devices use to accept removable accessories such as additional memory or GPS receivers.
contour interval - The difference, in feet or meters, in elevation between two adjacent contour lines.
contour line - A line on a topographic map that represents a specific elevation.
CONUS - Contiguous (or Continental) United States.
datum - (pl. datums) A point, line, or surface used as a reference, as in surveying or mapping.
dead reckoning - The technique of determining position by computing distance traveled on a given course. Distance traveled is determined by multiplying speed by elapsed time.
degree - A unit of measurement; 360 degrees equal one complete circle, as around the earth on a line of latitude; measured from 0 to 90 degrees from the equator to each pole along a line of longitude.
depression - An area in the surface of the earth that is lower in elevation than the surrounding area; a hole.
DGN - microstation design file - A file format/extension.
DGPS - Differential GPS - A method of improving GPS accuracy using measurements at a known location to improve the measurements made by other GPS receivers within the same general area.
dingle - A small, wooded valley.
DOQQ - Digital Orthophoto Quarter-Quadrangle - 1:12,000 scale representations of a quarter of the area of a conventional USGS 7.5 minute topographical map.
draw - A small, natural depression or valley in the side of a hill; a gully.
DRG - Digital Raster Graphics - See "Raster Maps."
DTAM - Digital world Tectonic Activity Map.
DXF - Drawing eXchange Format - Used for transfering CAD (Computer Aided Drafting) files.
EGNOS - European Geostationary Navigation Overlay Service - A European system of satellite navigation. It will augment the two satellite navigation systems now operating, the U.S. GPS and GNSS systems. It consists of three geostationary satellites and a network of ground stations. EGNOS will achieve its aim by transmitting a signal containing information on the reliability and accuracy of the positioning signals sent out by GPS and GNSS.
elevation - The vertical distance of a point above or below a reference surface, usually sea level.
ephemeris data - Precise orbital position and clock data for each GPS satellite. Valid for about 30 minutes.
GDOP - See Geometric Dilution of Precision
geofence - An imaginary boundary set which contains a GPS device - if that GPS device exceeds the boundary, an alarm is activated.
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.
geostationary - A satellite in a position always fixed to a relative point on the earth.
GIS - Geographic Information System - A system of hardware and software used for storage, retrieval, mapping, and analysis of geographic data.
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.
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, guide 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.
graticule - A network of parallels and meridians on a map or chart.
GSM - Global System for Mobile communications - A world standard for digital cellular communications.
hachure - Short lines attached to, and perpendicular with a contour line usually used to indicate a depression contour.
heading - The direction one is traveling.
latitude - The distance north or south of the equator of a point on the earth's surface.
longitude - The distance east or west of the prime meridian of a point on the earth's surface.
magnetic declination - The difference, in degrees, between magnetic north and true north.
magnetic north - A point on the earth about 500 miles from the north pole toward Hudson Bay in Canada; this is where a compass points. In the U.S., magnetic north can vary up to approximately 22 degrees from true north.
maidenhead grid squares - A system designed to facilitate the designation of geographical positions for use within the amateur radio community.
map projection - The method used to convert the spherical shape of the earth onto the plane of a map.
map projection deformation - The error or distortion that results when the spherical shape of the earth is projected onto the plane of a map.
mask angle - The minimum acceptable satellite elevation above the horizon to avoid blockage of line-of-sight.
meridian - An imaginary line circling the earth, passing through the north and south poles; a line of longitude.
MGRS - Military Grid Reference System.
minute - A unit of measurement; one degree contains 60 minutes.
morrow - A rounded hill.
multi-channel receiver - A GPS receiver that can simultaneously track more than one satellite signal.
multipath - Interference caused by reflected GPS signals arriving at the receiver, typically as a result of nearby structures or other reflective surfaces.
multipath error - An error caused by the interference of a signal that has reached the receiver antenna by two or more different paths. This is usually caused by one path being bounced or reflected.
NAVSTAR (Navigation Satellite Timing and Ranging) - The name given to the system of GPS satellites.
OSGB - Ordnance Survey of Great Britain - A system similar to the U.S. UTM for Great Britain.
parallel of latitude - An imaginary line circling the surface of the earth that is parallel to the equator; a line of latitude.
PCMCIA - Personal Computer Memory Card International Association - A standard for a credit card-size memory or input/output device that fits into a notebook, laptop or personal computer.
PDA - Personal Digital Assistant - A small mobile hand-held device that provides computing and information storage for personal or business use, often for keeping calendars and address information.
PDOP - See Geometric Dilution of Precision
photogrammetry - The process of making maps from photographs, usually aerial photographs.
Pocket PC - Software for personal digital assistants (PDAs) and any PDA that uses that software.
position fixing - Using a coordinate system to determine a point on a map's location.
Positional Dilution of Precision - See Geometric Dilution of Precision
prime meridian - A line of longitude at 0 degrees that runs through Greenwich, England; used as the origin for measurements of longitude.
prismatic compass - A compass that allows the user to see the compass face and distant locations at the same time.
qaud - See quadrangle.
quadrangle - A four-sided area of the surface of the earth used as a unit in mapping.
raster maps - Raster maps are commonly referred to as "bit mapped" and are in a GIF or JPEG format. Raster images are well-suited for web sites where editing or resizing are not required. They can be made smaller, but are not meant to be enlarged or customized in the ways that vector maps can be manipulated.
relief - Changes in terrain; elevations or depressions in the land.
relief shading - The use of light and dark tones to depict the form of the land; makes the map appear as if illuminated by the sun, creating highlights and shadows.
RFID - Radio Frequency Identification - A method of identification using radio frequency. For objects, animals, or people and does not require direct contact or line-of-sight scanning.
route - A set of waypoints that define the intended path of travel.
S/A - See selective availability.
saddle - A dip along the top of a ridge.
scale - The distance on a map that corresponds to the same points on the earth.
SD - See secure digital.
second - A unit of measurement; one minute contains 60 seconds; one degree contains 3600 seconds.
secular variation - Complex fluid motion in the outer core of the Earth that causes the magnetic field to change slowly with time.
secure digital - A type of technology for mass storage devices in the form of a type of memory media with a compact design and is compatable with different digital camera brands and MP3 devices.
selective availability - S/A - The intentional degradation of GPS accuracy for civilian use (S/A has been deactivated indefinitely as of May 2, 2000). S/A limited the accuracy of civilian GPS systems to 300 feet or less 95% of the time.
sleeve - An attachment for a PDA which allows you to use items like network or modem cards, PCMCIA or CF cards, digital cameras, a GPS/GPRS phone, or an extra battery pack with a PDA.
SMS - Short Message Service is the transmission of short text messages to and from mobile phones, pagers, fax machines, and/or IP address.
SOG - see Speed Over Ground
Speed Over Ground - The speed at which the GPS unit and the person operating it are moving with respect to the earth's surface.
spur - A small ridge.
TIGER - Topologically Integrated Geographic Encoding & Referencing - A U.S. Census Bureau mapping system.
time to first fix - See TTFF.
topography - The graphic representation of the landform on a map by the use of contour lines.
track - A collection of points that show the path travelled.
track point - A single point on the path travelled.
triangulation - The method of determining a location on a map by using two or more points through which lines of known directions are drawn; the intersection of these lines is the desired location; can use distance and/or angles.
trilateration - The same method as triangulation, except trilateration uses only distances for locating.
true north - The geographical north pole
TTFF - Time To First Fix - The time it takes for a GPS receiver to lock onto the satellite signals and determine the initial position.
Universal Transverse Mercator (UTM) - A coordinate system that uses a perpendicular grid with constant linear surface distance values between each of its grid lines in all directions. Coordinates are in meters as opposed to degrees, minutes, and seconds.
UMTS - Universal Mobile Telecommunications System - A transmission system for text, digitized voice, video, and multimedia for mobile computer and phone users no matter where they are located in the world.
UPS - Universal Polar Stereographic - An azimuthal projection that is used with Universal Transverse Mercator (UTM) projection systems to represent polar regions.
USGS - United States Geological Survey
UTM - See Univeral Transverse Mercator.
Vector map - Maps that use lines and polygons as opposed to pixels to display an image. Image resolution is sharp even when the image is displayed or printed at an enlarged perspective.