Position finding, function - GF82.95-P-3000PM

MODEL 203.0 /2 /7 with CODE (359) TELE AID emergency call system 

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

Position finding 

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

GPS position finding 

GPS position finding is necessary for journeys outside the digitized map area and after vehicle transport (e.g., train or ferry journeys and towing). A new GPS position finding (after interruption of satellite reception) can take several minutes (up to 20 minutes when the device is first put into operation). The processor and the GPS receiver unit are integrated in the emergency call control unit (N123/4). When signals from at least 3 satellites are received by the GPS antenna (A2/23), it is possible to calculate the position and accuracy of the receiver location (vehicle). In addition, the vehicle's direction of travel is determined using the sequence of locations calculated with GPS.

Basic location finding 

For basic position finding, which is undertaken in parallel to the GPS position finding, the emergency call system control unit (N123/4) requires the following information:

• The signals edited by the ESP and BAS control unit (N47-5) from the left front rpm sensor (L6/1) and right front rpm sensor (L6/2), that are sent over the Controller Area Network bus Class C (engine compartment) (CAN-C) to the central gateway control unit (N93) (up to 30.11.04) or the EIS control unit (N73) (as from 1.12.04). The central gateway control unit (N93) (up to 30.11.04) or the EIS control unit (N73) (as from 1.12.04) sends the message to the Controller Area Network (data bus/CAN bus) (CAN) diagnosis to the emergency call system control unit (N123/4).
• The data of the yaw rate sensor (gyro sensor) integrated in the emergency call system control unit (N123/4) which are used by the emergency call system control unit (N123/4) to calculate the vehicle's direction of travel (cardinal point).
• The data for direction of travel (forward or reverse)

The basic position finding is performed continuously by the emergency call system control unit (N123/4) with "circuit 15R ON". The momentary vehicle position (longitude/latitude) is calculated from the path traveled taking the vehicle alignment and direction of travel into consideration. 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 this over the vehicle's cell phone system. 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, the deviation is automatically corrected by the integrated navigation processor in the emergency call control unit (N123/4) when receiving GPS data.

	TELE AID control unit, location/task/design/function		GF82.95-P-4100PMU
	Global positioning system antenna, location/task		GF82.61-P-4107P