96
GSR2600
Appendix B
Glossary
Base Station -
In differential positioning, a base station is the
end of the baseline that is assumed known and its position fixed.
Carrier Phase -
The phase of either the L1 or L2 carrier of a GPS
signal, measured by a receiver while locked-onto the signal (also
known as integrated Doppler).
Cartesian coordinates -
Values representing a point’s location
within a plane in relation to three mutually perpendicular
coordinate axes which intersect at a common point or origin. The
point is located by measuring its distance from each axis along a
parallel to the axis.
Circular Error Probable (CEP) -
The radius of a circle, centered
at the user’s true location, that contains 50 percent of the
individual position measurements made using a particular
navigation system.
CMR -
Compact Measurement Record, a standard
communications protocol format used in Real-Time kinematic
systems to transfer GPS carrier phase and code observations
from a reference station to one or more rover stations.
Coarse Acquisition (C/A) Code -
The Course/Acquisition (or
Clear/Acquisition) code modulated onto the GPS L1 signal.
Control Segment -
The Master Control Station and the globally
dispersed reference Stations used to manage the GPS satellites,
determine their precise orbital parameters, and synchronize
their clocks.
Cycle slip -
A loss of the count of carrier cycles as they are being
measured by a GPS receiver. Loss of signal, ionospheric
interference, obstructions and other forms of interference cause
cycle slips to occur (see carrier phase).
Datum -
See Geodetic datum
Differential GPS (DGPS) -
A technique to improve GPS
accuracy that uses pseudorange errors at a known location to
improve the measurements made by other GPS receivers within
the same general geographic area.
Differential positioning -
Determines the relative coordinates
using two or more receivers that are simultaneously tracking the
same satellites. Dynamic differential positioning is a real-time
calibration technique achieved by sending corrections to the
750-1-0093 Rev 1.book Page 96 Friday, June 28, 2002 4:02 PM
