Ned Co-Ordinate Frame; Ecef Co-Ordinate Frame - Advanced Navigation Certus OEM Reference Manual

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11.6 NED Co-ordinate Frame

The NED (North East Down) co-ordinate frame is used to express velocities and relative positions. The origin of
the co-ordinate frame is the current position. From that origin, the north axis points true north and parallel to the
line of latitude at that point. The east axis points perpendicular to the north axis and parallel to the line of
longitude at that point. The down axis points directly down towards the centre of the Earth. See the figure below
for a graphical representation of the NED co-ordinate frame at a position on the Earth.
Figure 115: Graphic Showing Geodetic, NED and ECEF Co-ordinates

11.7 ECEF Co-ordinate Frame

The ECEF (Earth-centred earth-fixed) co-ordinate frame is a Cartesian co-ordinate frame used to represent
absolute positions on the Earth. Its origin is at the centre of the Earth. ECEF is an alternative to the geodetic co-
ordinate frame. It is represented by the three axes X, Y and Z which are presented graphically in
Graphic Showing Geodetic, NED and ECEF
Navigation products, however the geodetic system is used as the default.
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Co-ordinates. ECEF positions can be retrieved from Advanced
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Figure 115:
2024-12-17