Leica MX400 Operating Instructions Manual page 215

Operator's Manual
GEOGRAPHIC COORDINATES
Angular displacements along parallels of latitude and meridians
of longitude on an ellipsoidal surface. Ellipsoidal coordinates.
GEOID
The earth's surface with all topographical undulations removed
(equipotential surface) so that all points on the surface approxi-
mate mean sea level.
GEOIDAL HEIGHT
Deviations of the geoid above and below the ellipsoid due to
non-uniformity of the earth's mass. Geodal height is positive
when the deviation is outward from the central volume of the
ellipsoid, and negative when it is inward.
GDOP
An indicator of the accuracy in position (latitude, longitude,
altitude, and time). See DILUTION OF PRECISION.
GLOBAL POSITIONING SYSTEM (GPS)
The NAVSTAR Global Positioning System, which consists of
orbiting satellites, a network of ground control stations, and user
positioning and navigation equipment. The system has 24 plus 3
active spare satellites in six orbital planes about 20,200 kilome-
ters above the earth.
GMT
Greenwich Mean Time. See also UNIVERSAL TIME COOR-
DINATED.
GPS LOG
A feature of the navigator that measures the sailed distance
based on the GPS signals rather than a water distance sensor.
GPS SYSTEM TIME
Time corrected to Universal Time Coordinated (UTC) and used
as the time standard by the user segment of the GPS system.
GREAT CIRCLE NAVIGATION
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Glossary
Version 3.3