Location finding, function

P82.61-0246-01

Location finding with GPS

Illustration deviating from TELE AID system:Location of GPS/telephone roof antenna (A2/49) on trunk lid or at rear end of vehicle roof (varies according to model).

P82.61-0245-01

Location finding with dead reckoning

Illustration deviates from TELE AID system:Location of GPS/telephone roof antenna (A2/49) on trunk lid or at rear end of vehicle roof (varies according to model).

s Mileage traveled

With TELE AID the vehicle location is calculated by two methods which check each other. The methods are called GPS location finding and dead reckoning.

GPS location finding:

 GPS antenna depends on model:

Models 129, 215 GPS antenna (A2/23)

Models 202, 208.3, 210, 220 GPS/telephone roof antenna (A2/49)

The vehicle position (location precision approx. 100 m) is calculated in the global position system (GPS) control module by the signals received by theGPS antenna from min. 3 satellites. The GPS control module is integrated into the emergency call system control module (TELE AID, A35/8).

Dead reckoning:

For dead reckoning of the vehicle the emergency call system control module (TELE AID, A35/8) requires the following information:

 The signals edited by the traction system control module (N47) for the left front speed sensor (L6/1) and the right front speed sensor (L6/2)

 the reversing signal

 the signal from thestop lamp switch (S9/1)

The dead reckoning is permanently accomplished by the emergency call system control module (TELE AID, A35/8) with circuit 15R on:The momentary vehicle position is calculated from the path traveled considering the vehicle alignment and direction of motion.

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Mileage covered

The number of impulses from the front wheel speed sensors (L6/1 and L6/2) is a measure for the distance traveled.

Vehicle alignment

From the speed difference of the front speed sensors (L6/1 and L6/2) the emergency call system control module (TELE AID, A35/8) calculates the vehicle alignment.

Direction of motion

The reverse lamp signal indicates whether the vehicle moves forward or backward.

The stop lamp switch signal is only used for plausibility checks when calculating the location.

Positioning errors and corrections

Rolling backwards without the reverse gear being engaged is evaluated as forward motion, and may lead to an error in map matching. Rolling with the ignition switched off or vehicle transportation also falsify map matching.

The location finding errors are automatically corrected when receiving the GPS data.

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The vehicle should be (for correct dead reckoning) equipped with permissible tires and the TELE AID should be coded correspondingly with the aid of the hand-held tester.The same applies for changes on the chassis. Prerequisite for GPS location finding is a free view to the sky.

When initially started up or after interruption of the power supply the vehicle should be parked outdoors for approx. 30 minutes so that the GPS system can recalibrate. Otherwise it is not ensured with a TELE AID emergency call or a taxi emergency call that the correct vehicle position is entered into the emergency call telegram.