The Glossary Of GPS(2)

The Glossary Of GPS Between C-C

C/A Code
See Coarse/Acquisition Code.

Carrier Frequency
The frequency of an unmodulated output of a radio transmitter. The GPS L1 carrier frequency is 1575.42 MHz.

Cartography
The art or technique of making maps or charts. Many GPS receivers have detailed mapping—or cartography—capabilities.

CDI
See Course Deviation Indicator

CDMA
See Code Division Multiple Access.

Code Division Multiple Access (CDMA)
A method whereby many radios use the same frequency, but each one has a unique code. GPS uses CDMA techniques with codes for their unique cross-correlation properties.

Clock Bias
The difference between the indicated clock time in the GPS receiver and true universal time (or GPS satellite time).

Clock Offset
A constant difference in the time reading between two clocks, normally used to indicate a difference between two time zones.

CMG
See Course Made Good.

Coarse/Acquisition Code (C/A Code)
The standard positioning signal the GPS satellite transmits to the civilian user. It contains the information the GPS receiver uses to fix its position and time, and is accurate to 100 meters or better.

COG
See Course Over Ground.

Cold Start
The power-on sequence where the GPS receiver downloads almanac data before establishing a position fix.

Control Segment
A worldwide chain of monitoring and control stations that control and manage the GPS satellite constellation.

Coordinates
A set of numbers that describes your location on or above the earth. Coordinates are typically based on latitude/longitude lines of reference or a global/regional grid projection (e.g., UTM, MGRS, Maidenhead).

Coordinated Universal Time (UTC)
Replaced Greenwich Mean Time (GMT) as the world standard for time in 1986. UTC uses atomic clock measurements to add or omit leap seconds each year to compensate for changes in the rotation of the earth.

Course
The direction from the beginning landmark of a course to its destination (measured in degrees, radians, or mils), or the direction from a route waypoint to the next waypoint in the route segment.

Course Deviation Indicator (CDI)
A technique for displaying the amount and direction of crosstrack error (XTE).

Course Made Good (CMG)
The bearing from the 'active from' position (your starting point) to your present position.

Course Over Ground (COG)
Your direction of movement relative to a ground position.

Course To Steer
The heading you need to maintain in order to reach a destination.

Course Up Orientation
Fixes the GPS receiver's map display so the direction of navigation is always "up."

Crosstrack Error (XTE/XTK)
The distance you are off the desired course in either direction.