C-Nav 2050M User Manual - page 145
C-Nav2050 User Guide
boat. Generally, each set of coordinates is computed
from a single data sample. The GPS was originally
conceived for dynamic positioning of a single receiver,
however, it may be used in a differential mode to
increase relative accuracy.
Eccentricity is the ratio of the distance from the center
of an ellipse to its focus on the semi-major axis.
Elevation is the distance above or below Local Vertical
Datum.
Elevation Mask the lowest elevation, in degrees, at
which a receiver can track a satellite. Measured from
the horizon to zenith, 0º to 90º.
Ellipsoid is a mathematical model approximating the
ea
minor axis. GPS positions are computed relative to the
WGS-84 ellipsoid. An ellipsoid has a smooth surface,
a
Conventionally surveyed
oid, which has an
ximates the earth’s
tion of
e
rth’s surface, generated by rotating an ellipse on its
which does not match the earth’s geoidal surface
closely, so GPS altitude measurements can contain
large vertical error component.
ositions usually reference a ge
p
undulating surface and appro
surface more closely to minimize altitude errors.
Ephemeris is a tabulation of the positions of all GPS
satellites at given points in time.
Epoch is a period of time or a date selected as a point
of reference.
Error Ellipse is a statistical measure of the positional
error at a given point computed from the propaga
all errors affecting the position solution and expressed
by its semi-major and semi-minor axis (vectors of
greatest and least magnitude) and the covariance
(rotation angle in the reference coordinate system).
Two-dimensional errors are typically propagated at on
standard deviation (39.4% probability that the
G-13