Maps GPS Glossary - C

C/A code - Coarse Acquisition code - The GPS signal for civilian use (also used by the military to get an initial fix).

cadastre - A public record, survey, or map of the value , extent, and ownership of land as a basis of taxation.

calibration - The process of associating map information held in an image file with its location on the earth so that, for example, each pixel becomes associated with a latitude and longitude allowing routes and tracks to be correctly plotted and displayed.

carrier-aided tracking - A method to improve accuracy by using the GPS carrier signal to get a more precise lock on the pseudorandom code.

cartography - The art or technique of making maps or charts.

CEP - Circular Error Probable - The radius of a circle within which fifty percent of positioning solutions fall. CEP is used to achieve horizontal accuracy.

CF - Compact Flash - A standard that PDAs, laptops, and other computer-related devices use to accept removable accessories such as additional memory or GPS receivers.

channel - Circuitry necessary to receive the signal from one GPS satellite.

chartplotter - A device that overlays GPS data on to marine navigational charts.

circular error probable - See CEP.

Clarke 1866 - The reference spheroid for the NAD27 coordinate system.

clinometer - A device, usually similar to a compass, used to measure vertical angles, as in the slope of a hill.

CMG - see course made good

COG - see course over ground

cold start - The ability of a GPS receiver to start giving position data without any almanac data stored in its memory.

collar - The area surrounding the actual map itself containing necessary information such as scale, legend, latitude and longitude, etc.

compact flash - See CF.

constellation - 1) All GPS satellites. 2) The satellites visible to a GPS receiver at one time.

continental margin - The zone of transition from a continent to the adjacent ocean basin. It usually includes a continental shelf, continental slope, and continental rise.

continental rise - The gently sloping surface located at the base of a continental slope.

continental shelf - The submerged margin of a continental mass extending from the shore to the first prominent break in slope.

continental slope - The slope that extends from a continental shelf down to the ocean basin. In some areas, such as off eastern North America, the continental slope grades into the more gently sloping continental rise.

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.

control point - Also called a control station. Locations on the earth's surface used for mapping references. Can be horizontal or vertical or both. Often these are bench marks.

CONUS - Contiguous (or Continental) United States.

coordinates - A set of numbers that represents a precise location anywhere on Earth. Usually stated as latitude and longitude.

course - The direction from the starting waypoint or location to the destination waypoint, measured in degrees.

course made good - The bearing from the "active from" waypoint to the current position, independent of the path taken to arrive at the current position.

course over ground - The direction of movement relative to the Earth.

crosstrack error - The lateral distance in either dirction you are off the desired course.