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

Appendix B / Frames of Reference
_ _
this application, Z C in fact describes a circle with a period of some 26,000
years caused by lunar/solar induced torque on the Earth’s equatorial bulge.
E A R T H
O R B I T A L
P L A N E
X C
E
First Point in Aires
Z C
SUN
Vernal Equinox
ζ
15-4
Y C
Plane of the Ecliptic
Figure 15-1 : Celestial Frame of Reference
The Local Inertial frame (I) is a translated Celestial frame located at the
general point (p) that will depend on application.
15.2 NAVSTAR GPS Orbital Frames
The 6 GPS Satellite Orbital frames (O), one of which is shown in Figure
15-2, are Earth centred, and remain stationary with respect to the Celestial
frame. X O and Y O span the satellite orbital plane in which the line of nodes
NN ’ is defined by the intersection between the orbital and equatorial planes.
X O passes through the satellite ascending node (N), and Z O is normal to the
orbital plane.
The right ascension of the ascending node (Ω) is the angle measured from
X C to X O in the equatorial plane. The orbital planes are inclined at (ι := 55°)
to the equatorial plane with the position of a particular satellite around its
orbit defined by the Mean Anomoly (M), measured clockwise about Z O
from the ascending node.
15.3 Missile to Satellite LOS Frames
The 24 Missile-Satellite LOS frames (L) are located at the missile GPS
receiver reference point (g). The X L point to each satellite whilst the Y L are
contained in a plane parallel to the equatorial plane.
15.4 Earth Centred, Earth Fixed Frame
The Earth-Centred, Earth-Fixed (ECEF) frame (E) shown in Figure 15-3 is
located at the Earth’s geometric centre (r) and rotates with the Earth. X E lies
in the equatorial plane and passes through the line of zero longitude defined