Leica Geosystems GPS Basics - Manual (Page 52)

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GPS Basics -1.0.0en Glossary
Flattening
Relating to Ellipsoids.
f = (a-b)/a = 1-(1-e 2 ) 1/2
where a ... semimajor axis
b ... semiminor axis
e ... eccentricity
Fundamental frequency
The fundamental frequency used in GPS
is 10.23 MHz. The carrier frequencies L1
and L2 are integer multiples of the
fundamental frequency.
L1 = 154F = 1575.42 MHz
L2 = 120F = 1227.60 MHz
GDOP
Geometric dilution of precision
—> Dilution of precision
Geocentric
Relating to the centre of the earth.
Geodesy
The study of the earth’s size and shape
Geodetic Coordinates
Coordinates defining a point with
reference to an ellipsoid. Geodetic
Coordinates are either defined using
latitude, longitude and ellipsoidal height
or using Cartesian coordinates.
Geodetic Datum
A mathematical model designed to best
fit part or all of the geoid. It is defined by
an ellipsoid and the relationship be-
tween the ellipsoid and a point on the
topographic surface established as the
origin of datum. This relationship can
be defined by six quantities, generally
(but not necessarily) the geodetic
latitude, longitude, and the height of the
origin, the two components of the
deflection of the vertical at the origin, and
the geodetic azimuth of a line from the
origin to some other point.
Geoid
The particular equipotential surface
which coincides with mean sea level,
and which may be imagined to extend
through the continents. This surface is
everywhere perpendicular to the direc-
tion of the force of gravity.
Geoidal Height
See Geoid separation
Geoid separation
The distance from the surface of the
reference ellipsoid to the geoid mea-
sured outward along the normal to the
ellipsoid.
GPS
Global Positioning System