GF82.95-P-3000TM Position Finding, Function

GF82.95-P-3000TM Position Finding, Function
- with CODE (359) TELE AID emergency call system

The global positioning system (GPS) is a satellite-supported localizing system set up by the American Department of Defense. It is free and available worldwide. The GPS satellites continuously transmit time and position data (longitude/latitude).

Position finding
The vehicle location is determined parallel with 2 methods supplementing each other. The methods are called GPS position finding and basic position finding.

GPS position finding
GPS position finding is irreplaceable for journeys outside the digitized map area and after vehicle transport (e.g., train or ferry journeys and towing). Starting GPS position finding again (following interruption of the satellite reception) may take several minutes (for initial startup of the device up to 20 min). The processor and receiver unit for the GPS are integrated into the emergency call system control unit (N123/4). If signals from at least 3 satellites are received via the GPS antenna (A2/23) (model 211.2) or via the GPS antenna (A2/49a2) (model 211.0) (up to 31.5.06), or the GPS antenna (A2/49a2) (as of 1.6.06), the position and the accuracy of the positioning of the receiver (vehicle) can be calculated. 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 (N123/4) 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 Control Area Network bus, class C (engine compartment) (CAN C). The central gateway control unit (N93) receives this message and sends it over the Controller Area Network (databus/CAN Bus) (CAN) diagnostics to the emergency call system control unit (N123/4).
^ The data from the turn rate sensor (gyro sensor) integrated in the emergency call system control unit (N123/4) (the emergency call system control unit (N123/4) uses the data from the integrated gyro sensor 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 (N123/4) whenever "Circuit 15R ON".
The current vehicle position (longitude/latitude) is calculated from the traveled distance and under consideration of the vehicle orientation and direction of travel. If the computer calculates that the basic position finding is less precise than the GPS position finding, the currently calculated position is corrected with the aid of the GPS data. If an accident occurs, the emergency call system control unit (N123/4) automatically generates an emergency call telegram which contains 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.

Errors with basic position finding
Rolling backward with the ignition switched off or vehicle transportation also falsify position finding. In both cases, when the GPS data are received, the deviation is automatically corrected by the integrated navigation processor in the emergency call system control unit (N123/4).