HOW DOES THE NAVIGATION SYSTEM WORK?
The navigation system is a tool to assist the driver in daily traffic. The
system allows you to enter the destination and activate ªGuidanceº, and
the system provides guidance advice through both audio and visual
advice.
Determination of the vehicle position
The movement of the vehicle is measured by sensors which are
integrated into the navigation system. The distance driven is recorded by
an electronic signal from the speedometer and the rotary movements of
turns by the gyroscope (a rotary measurement system). The information
from these sensors is, however, not always exact as the values can be
affected by tire slippage, varying tire pressure due to changes in
temperature, etc.
Data from the sensors, in conjunction with positional information
received from the global positioning system is transmitted to the
navigation computer. The resultant calculated position is then compared
against the road network data stored on the CD-ROM in order to display
the current vehicle position.
GPS (global positioning system)
The global positioning system is based on the reception of navigation
signals from a total of 24 GPS satellites at a height of 20 920 km
(13 000 miles).
Signals from at least four satellites must be received to determine the
vehicle position with sufficient accuracy. The GPS receiver can handle up
to eight satellite signals simultaneously. This allows an accuracy of
approximately 100 m (328 ft), which is further improved by other
sensors so that a final accuracy of approximately6mto18m
(20 ft to 60 ft) can be reached.
When the vehicle is parked for a long period of time, the satellites
change their orbital positions. Therefore, when the ignition is turned on
again it can take a few minutes before the navigation system can pick up
enough satellites and evaluate the received signals.
²Sufficient reception is indicated by the green symbol that appears in
the system's display. If the satellite symbol remains red, the GPS
reception is not sufficient.
Introduction
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