GF82.95-P-3000QJ Location Finding, Function

GF82.95-P-3000QJ Location Finding, Function
- with CODE (349) E Call emergency call system
- with CODE (498) Japanese version


The global positioning system (GPS) is a satellite-supported location finding system set up by the US Department of Defense. It is not subject to fees and is available worldwide. 24 satellites are currently orbiting the earth on different courses. The GPS satellites are continually transmitting time and position data (longitude/latitude).

Location finding
The vehicle location is determined parallel with two methods supplementing each other. The methods are called GPS location finding and basic location finding (dead reckoning).

GPS location finding
GPS localizing is irreplaceable, especially in the case of journeys outside of the digitalized map area and following vehicle transportation (e. e. train, ferry and towing).
A repeated GPS location finding (following satellite reception interruption) can take several minutes (when the unit is initially started, up to 20 minutes).
The GPS computer with the receiver unit is integrated into the E-call control module (A35/8). If signals are received from at least 3 satellites via the GPS antenna (A2/23), it is possible to calculate the position and the accuracy of the location finding of the receiver (vehicle) (positioning accuracy 100 m).

In addition, the vehicle's direction of travel is determined with the aid of the sequence of the locations calculated with GPS.

The basic location finding is determined in parallel with the GPS location finding.

Basic location finding (dead reckoning)
For basic location finding (dead reckoning) of the vehicle position the E-call control module (A35/8) requires the following information:
^ the signals from the left front rpm sensor (L6/1) and right front rpm sensor (L6/2) processed by the ESP and BAS control module (N47-5).
the number of pulses of the rpm sensor indicates the distance traveled.
^ the integrated (gyro sensor) rotation-rate sensor data in the E-call control module (A35/8).
the gyro sensor data is used by the E-call control module (A35/8) to calculate the vehicle orientation (direction).
^ The data on the direction of travel
^ The signal from the active rpm sensor and the backup lamp is used to determine whether the vehicle is moving forwards or backwards.

The basis location finding is carried out continually (once per second) by the E-call control module (A35/8) with "circuit 15R ON". The distance covered, taking the vehicle orientation and direction of travel into account, is used to calculate the instantaneous vehicle position (longitude/latitude).
If the computer calculates that the basic location finding is less precise than the GPS location finding, the currently calculated position is corrected with the aid of the GPS data.
If an accident occurs, the E-Call control module (A35/8) automatically generates an emergency call telegram which contains the positional data of the vehicle and transmits this over the vehicle's mobile phone system.
With the available equipment (graphic supported work station and electronic road data base) it is possible to determine the precise location of the vehicle with the aid of the position data.

Positioning errors in basic map matching
Rolling backwards without the reverse gear engaged is evaluated as forwards motion, and may lead to an error in the location finding. Rolling with the ignition switched off or vehicle transportation also falsify location finding.

In both cases, any deviation is automatically corrected by the computer in the E-call control module (A35/8) when GPS data is received.

Position finding using GPS shown on model 230







Basic position finding (dead reckoning navigation) shown on model 230

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