Location finding, function - GF82.95-P-3000B

MODEL 129, 202, 208.3, 210, 215, 220 with CODE (348a) EMERGENCY CALL system with CODE (498) Japanese version 

MODEL 203, 215, 220 with CODE (349) E-CALL emergency call system with CODE (498) Japanese version 

Location finding with GPS 

Illustration deviating from EMERGENCY CALL system: Location of global positioning system (GPS) antenna (A2/23)  responsible for location finding on trunk lid cover (model 129), in trunk lid cover (model 215) or of GPS/telephone roof antenna (A2/49)  and integrated GPS antenna (A2/49a2)  at rear end of vehicle roof (models 202, 208.3, 210, 220).

On model 203 the global positioning system antenna (GPS) (A2/23)  is glued to the rear window from inside

Location finding with dead reckoning 

For EMERGENCY CALL the vehicle location is calculated in parallel by two methods for mutual coordination. The methods are called GPS location finding and dead reckoning.

GPS location finding  :

On models 202, 208.3, 210, 220 the vehicle position is calculated with the signals received from at least three satellites by the GPS roof antenna (A2/49a2)  in the global positioning system control module (GPS) (location finding accuracy approx. 100 m).

On Models 129, 203, 215 these signals are received by the GPS antenna (A2/23)  on/in the trunk lid cover or on the rear window.

The GPS control module is integrated in the E-CALL control module (A35/8) 

Dead reckoning  :

For dead reckoning of the vehicle position the E-CALL control module (A35/8)  requires the following information:

• the signal edited by the traction system control module (N47), left front speed sensor (L6/1) 
• Reverse signal
• the signal from the stop lamp switch (S9/1) 

Dead reckoning is accomplished continuously by the E-CALL control module (A35/8)  with "circuit 15R: ON". The current vehicle position is calculated from the mileage traveled under consideration of the vehicle alignment and direction of motion.

Mileage covered 

the number of impulses from the left front wheel speed sensor (L6/1) is a measure for the distance traveled,

Vehicle alignment 

A gyro sensor is integrated in the E-CALL control module (A35/8)  which defines the vehicle alignment together with the left front wheel sensor (L6/1) data

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 tests when the location is calculated.

Location finding errors and correction 

Rolling backwards without the reverse gear engaged is evaluated as forward motion, and may lead to an error in map matching. Rolling without ignition switched on or transporting the vehicle also leads to erroneous location finding.

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

The vehicle should be equipped with permissible tires (for correct dead reckoning). Prerequisite for GPS location finding is a free view of the sky.

When initially started up or after the power supply is interrupted the vehicle should be parked outdoors for at least 15 min. so that the GPS system can recalibrate. Otherwise in the event of an EMERGENCY CALL it is not ensured that the correct vehicle position is entered into the emergency call telegram.

	Emergency call telegram generation, function		GF82.95-P-2004B
	Emergency call telegram transmission, function		GF82.95-P-2005B
	E-CALL control module, location/purpose/design		GF82.95-P-4200A
	Global positioning system antenna, location/purpose/design/function	Model 129	GF82.61-P-4106A
		Model 203	GF82.61-P-4106F
		Model 215	GF82.61-P-4106C
	GPS/telephone roof antenna, location/purpose/design/function	Models 202, 208.3, 210, 220	GF82.70-P-4111B