| Navigation SystemA navigation system is understood to mean an electronic unit that helps users to find their way to a desired destination. It guides the driver along the ideal route to any chosen destination by means of acoustic announcements and visually displayed directions.
The system is made up of the following main elements: a GPS aerial, a navigation computer and a display. With the aid of the aerial for the Global Positioning System (GPS), the navigation system receives signals from satellites located in a geostationary orbit around the earth. These signals make it possible to determine the vehicle’s position on the earth’s surface to within just a few metres.
Using this constantly updated information on the position of the moving car and by comparing it with the values provided by the wheel speed sensors of the anti-lock braking system, the computer can calculate the vehicle’s route. For this purpose, it requires the complete road network in digitised form as its base information. This information, the complete German road network for example, is compiled on a data medium (CD-ROM or DVD) which the navigation computer accesses.
Once a destination has been entered, the integrated navigation computer calculates the fastest or shortest route and compares the calculated route with the vehicle’s current position throughout the journey. If these do not coincide – because the driver has decided to take a different route to avoid a traffic jam or has taken a wrong turn, for example – an adapted route is calculated.
Dynamic route guidance is possible with the Traffic Message Channel (TMC). This enables the navigation system to detect traffic hold-ups automatically and offer an alternative route. |
