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

MODEL 204.0 /2 with CODE (498) Japan version up to Model Year 8 

Function requirements 

General position finding 

GPS 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).

Basic position finding runs parallel to GPS position finding.

The position finding function consists of the following subfunctions:

Function sequence for GPS position finding 

The global positioning system receiver is integrated into the COMAND controller unit. It receives the GPS signals from the multifunction antenna (A28/11) in the following way:

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

Basic position finding function sequence 

For basic position finding the COMAND controller unit requires the following information:

The wheel speed signals are recorded by the following RPM sensors:

The wheel speed signals are received by the COMAND controller unit from the RPM sensors in the following way:

The distance traveled data is received by the COMAND controller unit from the instrument cluster (A1) in the following way:

The vehicle alignment data (cardinal points) is internally processed by the COMAND controller unit's integrated turn rate sensor (gyro sensor).

The direction of travel data (forwards or backwards) is received by the COMAND controller unit over the interior CAN from the front SAM control unit with fuse and relay module.

After this the COMAND controller unit uses the distance traveled, the vehicle alignment and the direction of travel to calculate the vehicle position (degree of longitude and degree of latitude) at any given time.

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

IMPORTANT Error 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 instances the deviation is automatically corrected by the COMAND controller unit's integrated navigation processor upon reception of GPS data.

IMPORTANT Possible 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:

Destination-oriented navigation function sequence 

The destination-oriented navigation consists of the following subfunctions:

Destination-oriented navigation function sequence 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 placed on the Media Oriented System Transport (MOST) via the COMAND controller unit and then amplified in the sound system amplifier control unit (N40/3) (with code (810) Sound system).

The voice signals are transmitted on discrete lines via the sound system amplifier control unit to the following speakers:

IMPORTANT In vehicles except code (810) Sound system, the voice output takes place on discrete lines via the COMAND control unit to the following speakers:

Destination-oriented navigation function sequence through visual display

The signals for destination-oriented navigation visual display (map navigation) are generated by the COMAND controller unit and forwarded over a low voltage differential signaling (LVDS) line to the Audio/COMAND display (A40/8).

The Audio/COMAND display switch-on request is generated by the COMAND controller unit over the telematics CAN.

VICS function sequence over FM multiplexer

The driver is provided with vital information by the VICS on the current traffic situation. Traffic impairments and traffic jams are shown on the map, however they are not incorporated into the dynamic route guidance. The radio antenna signal path is as follows:

The VICS information is processed in the FM multiplexer integrated into the COMAND controller unit. Next, the information is shown on the Audio/COMAND display. Apart from this, the FM multiplexer can also receive additional information, e.g. on the weather or earthquakes.

Dynamic route guidance function sequence, VICS (dealer option) Dynamic route guidance requires the so-called VICS control unit (A2/37) (dealer option). The VICS control unit contains both the receiver and the antenna. The antenna communicates with the VICS beacons (transmission rods) installed on the roads, which transmit FM or infrared signals. Received signals are sent directly to the COMAND controller unit where they are decoded. The traffic messages are stored and made available to the navigation processor in the following way:

The traffic data recorder decodes the traffic information and forwards it to the navigation processor upon request. The navigation processor makes the decision whether the route should be changed. If necessary, a message that the route was changed is output via the vehicle speaker.

REFER TO SYSTEM WIRING DIAGRAMS Electrical function diagram for navigation system   PE82.85-P-2051-99FAC
  Front central operating unit, component description A40/9 GF54.21-P-4500CW
  Cockpit central display, component description A40/8
High		 GF54.30-P-6100CWH
  COMAND controller unit, component description A40/3 GF82.85-P-3136CWJ
  Speaker system, component description H4/1, H4/2, H4/3, H4/4, H4/27 Except code (810) Sound system GF82.62-P-4220CW 
H4/1, H4/2, H4/3, H4/4, H4/27, H4/29, H4/54, H4/57 with CODE (810) Sound system GF82.62-P-4220CWS 
  Audio tuner control unit, component description N40/3
with CODE (810) Sound system		 GF82.62-P-3132CWS 
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