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Position finding and destination-oriented navigation, function - GF82.61-P-2010GQ

MODEL 164.1 with CODE (527) COMAND APS with single DVD drive (with navigation) except CODE (498) Japan version as of model year 09/YoM 08 model refinement package 

MODEL 164.1 with CODE (512) COMAND APS with DVD changer as of model year 09/YoM 08 model refinement package 

MODEL 164.8 with CODE (527) COMAND APS with single DVD drive (with navigation) except CODE (498) Japan version as of model year 09/YoM 08 

MODEL 164.8 with CODE (512) COMAND APS with DVD changer as of model year 09/YoM 08 

MODEL 251.0 with CODE (527) COMAND APS with single DVD drive (with navigation) except CODE (498) Japan version as of model year 09/YoM 08 

MODEL 251.0 with CODE (512) COMAND APS with DVD changer as of model year 09/YoM 08 

MODEL 251.1 with CODE (527) COMAND APS with single DVD drive (with navigation) except CODE (498) Japan version as of model year 09/YoM 08 

MODEL 251.1 with CODE (512) COMAND APS with DVD changer as of model year 09/YoM 08 

Function requirements 

General 

The position finding and destination-oriented navigation function is divided into the following subareas:

General information on GPS position finding 

The GPS is a satellite-based positioning system. It is available worldwide. The GPS satellites permanently transmit time and position data (longitude and latitude).

GPS position finding is irretrievable after vehicle transport (e.g. by train or ferry or after towing). A new GPS position (after interruption of the satellite reception) can take several minutes (up to 20 minutes when the equipment is commissioned). The accuracy of the position finding and the actual calculation is essentially based on the measurement of the run-times of the signals transmitted synchronously by the various satellites. A vital precondition is the synchronicity of the clocks in the satellites and in the receiver. To this end the receiver is equipped with an automatic time correction, which in turn is made possible with the aid of the satellite signals.

GPS position finding function requirements 

Function sequence for GPS position finding 

The GPS signals are received by the GPS receiver integrated in the COMAND operating, display and controller unit (A40/3) via the following path:

The GPS signals are used by the COMAND operating, display and controller unit to calculate the momentary position of the vehicle (receiver). In addition, the vehicle's direction of travel is determined with the aid of the sequence of the locations calculated with GPS.

IMPORTANTPossible problems in GPS signal reception 

Since GPS operates in the giga hertz (GHz) range (microwaves) and the signals are weak, reception interference can occur as a result of the following events:

General information on basic position finding 

Basic position finding runs parallel to GPS position finding. The COMAND operating, display and controller unit requires the following information for basic position finding:

Basic position finding function requirements 

Basic position finding function sequence 

For basic position finding the COMAND operating, display and controller unit requires signals from the following components:

The COMAND operating, display and controller unit receives the wheel speed signals from the listed rpm sensors in the following way:

The data in the turn rate sensor (gyro sensor) integrated into the COMAND operating, display and controller unit is forwarded within the COMAND operating, display and controller unit.

The data about the direction of travel (forward or backward) is received by the COMAND operating, display and controller unit in the following way:

After this, the COMAND operating, display and controller unit uses the distance traveled, the vehicle alignment and direction of travel as well as the previous location to calculate the instantaneous vehicle position (longitude and latitude).

The steering angle signal from the steering angle sensor (N49) is forwarded to the COMAND operating, display and controller unit via the following route:

DENMARK ONLY Calculation of the basic position finding takes approx. 1/s.

IMPORTANTError during position finding 

Basic position finding is falsified when a vehicle rolls backwards with "circuit 15 OFF" (ignition switched off) or if it is transported somewhere. In both cases, the deviation is corrected automatically by the navigation processor integrated into the COMAND operating, display and controller unit.

Recalibration 

Because of the tire abrasion, a constant recalibration of the tire circumference is required. It is carried out automatically and uses the difference between the calculated and actually traveled distance between 2 turning points calculated with the aid of map-based position finding.

General information on route calculation 

The following stretches can be excluded from the route calculation in the navigation (Navi) base function under the "Mode" menu item:

For vehicles except code (494) USA version, additional stretches can be excluded from the route calculation:

Route calculation is accomplished using the options set to the best possible extent. If observance of the options is not possible, then the options set are ignored for the sections in question and a message is displayed and signaled audibly.

The set criteria and options can be displayed and changed at any time. After successful calculation, the route is displayed on the map and the information is relayed acoustically - "Route calculated".

Function sequence for destination-oriented navigation through voice output 

The integrated navigation processor continuously compares the route calculation data with the position finding data and uses the data to deduce measures for further destination-oriented navigation. The voice output for destination-oriented navigation is sent to the Media Oriented System Transport (MOST) and then amplified in the amplifier for sound system (N40/3), with code (810) Sound system.

The voice output is sent to the following speakers via direct lines using an audio signal:

IMPORTANT The audio signal for the subwoofer speaker (H4/29) travels from the COMAND operating, display and controller unit to the sound system amplifier via MOST and from there, over direct lines, to the subwoofer amplifier (N40/9) and then to the subwoofer speaker.

In vehicles without code (810) Sound system, voice output is performed over the following speakers via direct lines by the COMAND operating, display and controller unit using an audio signal:

The signals for visually displaying navigation (map navigation) are generated by the COMAND operating, display and controller unit and shown on the display on the COMAND operating, display and controller unit, and also in the instrument cluster (A1) in the form of arrow pictographs.

General on dynamic route guidance, except code (494) USA version 

The current traffic situation is taken into consideration in the dynamic route guidance. The incoming information on the traffic situation can be received by the radio data system/Traffic Message Channel (RDS/TMC) function via FM radio. The information on the current traffic situation is sent out by a specially equipped broadcasting corporation on an area-related basis via FM. A suitable FM/RDS transmitter must be tuned in. The traffic data recorder decodes the traffic information and forwards it internally to the navigation processor upon request. The navigation processor makes the decision whether the route should be changed. Where applicable, a message is output on the above vehicle loudspeakers that the route has been changed.

Function sequence dynamic route guidance, except code (494) USA version 

The FM receiver in the COMAND operating, display and controller unit receives the traffic messages from the FM rear window antenna amplifier (A2/19) and forwards them to the roof antenna module (A2/93). From there the traffic messages are forwarded to the traffic data recorder in the COMAND operating, display and controller unit. The traffic reports are stored in the traffic data recorder of the COMAND operating, display and controller unit and made available to the integrated navigation processor. The voice output for dynamic route guidance is placed on the MOST ring and then amplified by the amplifier for amplifier for sound system, with code (810) Sound system. The audio signals are sent via direct lines to the above vehicle speakers.

In vehicles without code (810) Sound system, the voice output for dynamic route guidance is performed over the above vehicle speakers via direct lines by the COMAND operating, display and controller unit using an audio signal:

Destination-oriented navigation through driving lane recommendations 

For certain turnoff situations on multiple-lane exit points (e.g. freeway intersections), driving lane recommendations are shown in the bottom line.

Along with a turnoff recommendation, the distance to the actual turnoff point is also displayed by means of a bar graph. The lanes have arrows assigned to them, which indicate on which lane the destination can be reached or the best way to reach it.

The following colors apply for representation on the display of the COMAND operating, display and controller unit:

IMPORTANT The instrument cluster only displays the midnight blue arrows.

Map function 

The map display is always controlled by the COMAND operating, display and controller unit.

REFER TO SYSTEM WIRING DIAGRAMS Electrical function diagram for position finding and navigation (COMAND), function Model 164 PE82.85-P-2062-97MAA
Model 251 PE82.85-P-2062-97RAA
  Instrument cluster, component description A1 GF54.30-P-6000GM
  COMAND operating, display and controller unit, component description A40/3 GF82.85-P-3134GQ
  Sound system amplifier, component description N40/3
With CODE (810) Sound system		 GF82.62-P-6003GQS
  ESP control unit, component description N47-5 GF42.45-P-5118GM
  Component description for the steering column module control unit N80 GF54.21-P-6051GM
  Central gateway control unit, component description N93 GF54.21-P-4170GM
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