Map-supported location finding, function - GF82.61-P-3008C

MODEL 163, 168, 170, 203.0 /2 /7, 208, 209.3 /4, 210 with CODE (353) Audio 30 APS

Basic representation of the map-supported location finding shown on model 210

Map-supported location finding (map matching) is available only in the digitized area of the DVD map.

A deviation can be recognized and corrected automatically by comparing the calculated position of the vehicle with the possible positions on the DVD map.

Fig 1: Identifying Map-Supported Location Finding Function

Function

The position of the vehicle is continuously followed on the DVD map by the navigation processor. A number of alternative routes are calculated preliminarily in the digitized area of the DVD map. If the route driven varies from one of the possible routes, the position coordinates for basic location finding are corrected where necessary.

The navigation processor is integrated in the radio (A2).

Loading the DVD map data

The navigation processor has a read/write memory (RAM) for storing the DVD map data. However, this memory is not large enough to store the entire DVD map (currently approx. 10 %). For this reason, the navigation processor loads into the memory only the map data required for route guidance.

Here, different storage methods are used depending on whether the destination is in the near vicinity of the vehicle or further away:

The following methods are used to store the data:

If the destination is in the near vicinity, a map area is loaded within a radius of approx. 100 km of the vehicle location ("Local area").
For destinations further away, an area is selected surrounding the vehicle location, the destination and the concrete route to the destination ("Corridor formation").

After storing the map data, the DVD with the map data can be taken out of the drive. Now, audio CDs can also be played.

If the driver deviates too far from the calculated route during the course of navigation system and thereby leaves the map area stored in the navigation processor, it may be necessary to insert the DVD again in order to calculate a new route. The navigation processor requests this automatically.

Location errors

The errors are classified into 2 categories:

Incorrect position indication between 2 driving instructions (may not occur more than once every 500 km)
Incorrect driving instruction (may not occur more than once every 1,000 km)

Global positioning system location finding, function

GF82.61-P-3007C