Nokia 5140 Manual Do Serviço
NPL-4/5
System Module and User Interface
Nokia Customer Care
Page 44
Copyright © 2004 Nokia Corporation. All rights reserved.
Issue 1 05/04
Figure 13: Earth’s Magnetic Field
Heading angle or azimuth (α)
The angle between magnetic north and the heading direction. Magnetic north is the
direction of x
direction of x
h
y
h
the earth´s field component perpendicular to gravity. Throughout this
paper, x
h
y
h
will be referred to as “horizontal” component of the earth´s field.
The compass heading is defined by:
The azimuth is the reading quantity of a compass. Throughout this paper, α is counted
clockwise from magnetic north, i.e. north is 360° or 0°, east is 90°, south is 180°, west is
270°.
clockwise from magnetic north, i.e. north is 360° or 0°, east is 90°, south is 180°, west is
270°.
Inclination (δ)
Also known dip. The angle between the earth´s field vector and the horizontal plane. As
already pointed out, the inclination varies with the actual location on earth, being zero
at the equator and approaching ±90° near the poles.
already pointed out, the inclination varies with the actual location on earth, being zero
at the equator and approaching ±90° near the poles.
Declination (λ)
The angle between geographic or true north and magnetic north. Declination is depen-
dent on the actual position on earth. It also has a long-term drift. Declination can be to
the east or to the west and can reach values of about ±25°. The azimuth measured by a
compass has to be corrected by the declination in order to find the heading direction
dent on the actual position on earth. It also has a long-term drift. Declination can be to
the east or to the west and can reach values of about ±25°. The azimuth measured by a
compass has to be corrected by the declination in order to find the heading direction
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
=
h
h
x
y
Heading
arctan
)
(
α