GF82.95-P-3000SXR Position Finding, Function
GF82.95-P-3000SXR Position Finding, Function
- Model 221
- with CODE (389) Mobile phone preinstallation with universal interface, USA/Canada
If an accident occurs, the emergency call system control unit (N123/4) automatically generates an emergency call telegram containing the vehicle position data and transmits the telegram over the cellular telephone system of the vehicle. The emergency call signal reaches the service provider. With the equipment there, the exact position of the vehicle is determined using the position data. The vehicle position data are determined in parallel with 2 methods which complement each other. The methods are known as Global Positioning System (GPS) position finding and basic position finding.
GPS position finding
The GPS is a satellite-assisted localizing system that has been set up by the American Ministry of Defense. It is free and available worldwide.
The GPS satellites permanently transmit time and position data (longitude and latitude). GPS position finding is irreplaceable for journeys outside the digitized map area and after vehicle transport (e.g. by train or ferry or after towing). Relocating with GPS (after interruption of satellite reception) may require several minutes (up to 20 min when emergency call system control unit is commissioned). The processor and receiver unit for the GPS are integrated into the emergency call system control unit. If signals from at least 3 satellites are received on model 221 over the telephone and GPS roof antenna (A2/49), or on model 216 over the telephone and GPS antenna (A2/49), it is possible to calculate the position and the accuracy of position finding of the receiver (vehicle). In addition, the vehicle's direction of travel is determined with the aid of the sequence of the locations calculated with GPS.
Basic location finding
For basic position finding, which runs in parallel to the GPS position finding, the emergency call system control unit requires the following information:
^ The signals processed by the ESP control unit (N47-5) from the left front rpm sensor (L6/1), right front rpm sensor (L6/2), left rear rpm sensor (L6/3) and right rear rpm sensor (L6/4) are sent to the central gateway control unit (N93) over the chassis CAN. The central gateway control unit receives the message and transmits it over the diagnostic CAN to the emergency call system control unit.
^ The data of the turn rate sensor (gyro sensor) integrated in the emergency call system control unit (the emergency call system control unit uses these data to calculate the vehicle orientation (compass direction)).
^ The data on the direction of travel (forward or reverse).
The basic position finding is performed continuously by the emergency call system control unit with "circuit 15R ON". The current vehicle position (longitude/latitude) is calculated from the traveled distance under consideration of the vehicle orientation and direction of travel.
Errors with basic position finding
Rolling backwards with "circuit 15 OFF" (ignition switched off) or a transport of the vehicle can falsify the position finding. In both cases, when GPS data are received, the deviation is automatically corrected by the navigation processor integrated into the emergency call system control unit.
Tracking (dynamic assignment)
Tracking is used e.g. to be able to track stolen vehicles.
Actuation
To track the vehicle, the function has to be activated first. The following possibilities exist to do this:
^ Customer reports the theft
^ The anti-theft alarm system (ATA) is active for more than 30 s
The difference in procedures only lies in how tracking is activated.
Reporting a theft (over the phone)
The customer calls the service provider and reports the theft of the vehicle. Next, the customer has to prove his/her identity. This is accomplished with the user name and the Personal Identification Number (PIN) of the customer. If the service provider has determined that the message has been received from a proper customer then the function is activated by telephone.
To do so, the service provider transmits an initiation command to the vehicle. The vehicle receives the message on model 221 over the telephone and GPS roof antenna and on model 216 over the telephone and GPS antenna and forwards the message to the emergency call system control unit.
The emergency call system control unit activates the locating calculation, which is performed with the aid of the satellite signals that are received on model 221 over the telephone and GPS roof antenna and on model 216 over the telephone and GPS antenna. Next, the emergency call system control unit cyclically transmits the position data to the service provider. The service provider forwards the location of the vehicle to the command staff (e.g. police). The command staff can activate the hands-free system and decide, whether to eavesdrop or talk to the driver.
ATA (automatic)
If the ATA is triggered and is active for more than 30 s, the emergency call system control unit establishes a voice connection to the command staff. The emergency call system control unit activates the locating calculation, which is performed with the aid of the satellite signals that are received on model 221 over the telephone and GPS roof antenna and on model 216 over the telephone and GPS antenna.
Following this, the emergency call system control unit sends the position data cyclically to the service provider on model 221 over the telephone and GPS roof antenna and on model 216 over the telephone and GPS antenna. The service provider forwards the location of the vehicle to the command staff (e.g. police).
Tracking can only be deactivated by the service provider.
