Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

Appendix B / Frames of Reference
_ _
by the poles and Greenwich (London). Z E passes through the north pole. In
1984 the International Earth Rotation Service created the WGS 84 standard
comprising the zero reference meridian and axis of rotation that define X C
and Z C .
C
X
15.5 Alignment Frame
s
O
Z
EQUATORIAL
PLANE
S A T E L L I T E O R B I T A L
P L A N E
Ω
15-5
N'
Z E
C
Z
r
N
X O
Figure 15-2 : Celestial and GPS Satellite Orbital Frames
The Alignment Frame (A), shown in Figure 15-3, is fixed with respect to the
Earth at point (o). X A is an easterly tangent to the Earth’s surface parallel to
the equatorial plane. Z A lies along the ray from the Earth geometric centre
(r) through point (o). Y A lies in the local meridian plane spanned by Z E and
Z A pointing in a northerly direction.
15.6 Local Geodetic Axes
Generic LGA (G), an example of which is shown in Figure 15-3, are located
a general point (p) above the Earth’s surface. Z G points away from the Earth
along the bi-normal vector to the tangent plane at the Earth’s equipotential
surface. X G lies parallel to an easterly tangent at the Earth’s surface. Y G
points north in the local meridian plane spanned by Z E and Z G . The geodetic
vertical of the LGA located at point (m) passes through point (d) on the
WGS-84 geoid, and point (f) on the Earth’s surface.
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