Continuous location finding, function

P82.61-0453-01

P82.61-0454-01

P82.61-0452-01

GPS satellite location finding

(Illustrated on model 210)

Basic location finding (dead reckoning) with compass direction (turn rate sensor) and distance driven (speed sensor).

Map-assisted location finding
(map matching)

General
Constant location finding is performed by calculation of the current vehicle position in the navigation processor (A2/30). It is active when the ignition is switched on. During the switch-on phase (software loading phase) only the basic location finding is available. After switching off the ignition all important location parameters are stored in a non-volatile memory.

Basic location finding (dead reckoning):
For basic location finding of the vehicle the navigation processor (A2/30) requires the following information:

 The speed signals from the non-driven wheels edited by the traction system control module (N47).

 The signal for the reverse lamp

 The signals of the turn rate sensor (integrated into
navigation processor (A2/30))

Basic location finding (dead reckoning) is the basic function for continuous location finding. It is performed continuously and is independent of the CD-ROM map.

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Map-assisted location finding (map matching):
Map matching serves for correction of the location values calculated with the aid of dead reckoning. If the calculated location of the vehicle deviates from the location on the digitalized CD-ROM map, it can be corrected on the basis of the map data.

GPS location finding:
The location of the vehicle (accuracy approx. 100 m or greater) is calculated by the global positioning system (GPS) control module using signals from at least 4 simultaneously received satellites. If the location calculated by dead reckoning is outside of the uncertainty window calculated by the navigation processor (A2/30) (depending on the number of satellites received), or if the location calculated by dead reckoning is evaluated as less precise than the GPS location by the navigation processor (A2/30), the currently calculated location is corrected with the aid of the GPS data.

Entry into map area
Upon entry into the CD-ROM map area the possible streets on which the vehicle may be located are determined by the the navigation processor (A2/30) with the aid of the GPS location and the GPS uncertainty window.

Driving outside of CD-ROM map
Outside of the CD-ROM map boundaries (outside of country) only dead reckoning is accomplished with correction using the GPS data (no map matching). The message "NO MAP" appears on the display.

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