9
Mk-3 navigation
Speed Signals
A speed signal is provided to the navigation computer for detection of distance traveled and
vehicle speed to calculate the vehicles position on the digital map. The input is a processed
signal provided by the vehicles DSC control unit.
E46: The speed signal used is from the l le
ef
ft
t
r
re
ea
ar
r
wheel.
E38/E39/E52/E53: The speed signal used is from the l le
ef
ft
t
f
fr
ro
on
nt
t
wheel.
Reverse Gear Input
The reverse gear input is used by the navigation computer to distinguish between the
vehicle backing up or turning around.
E38/E39/E52/E53: The reverse input is a high signal produced by the LCM III.
•E46: The reverse input is a high signal supplied by a splice from the back-up lights.
Mk-3 NAV
GS 20 Reverse
lightsReversing
Light Relay
K6325 KL15KL30
LCMMk-3 NAV
Reverse
lights
Automatic Transmission
version shown
10
Mk-3 Navigation
Principle of Operation
The Global Positioning System is a satellite based system developed by the US Department
of Defense that provides both military and civilian users accurate information about
location.
The GPS system uses 24 satellites in six
orbits 12,550 miles above the Earth mov-
ing at 1.7mi per second. Usually 7 to 10
satellites are in view over any one point on
the earth.
The GPS satellites are basically extremely
accurate clocks that broadcast a coded
signal representing time. The GPS receiver
determines it’s distance from the satellite
by measuring the time it takes between
satellite transmission of the signal and
reception to the receiver. The receiver
does this with at least 2 other satellites and
uses the information to determine the vehi-
cles latitude, longitude, and altitude. The
accuracy of the system for civilian use is
within 100m (300ft).
The vehicle must have an unobstructed view of the sky to receive the maximum amount of
satellite signals. Trees, large buildings and excessive cloud cover can block the reception
of the satellites’ transmissions.
