Navigation, function - GF82.61-P-2003FQM

MODEL 218 with CODE 357 (Map navigation) without CODE 509 (Navigation box) 

Function requirements for SD (Secure Digital) card navigation, general 

• Circuit 30g ON
• Transport mode not active
• Authorized SD card for CODE 357 (Map navigation) is inserted into the SD card drive
• Signals from at least four global positioning system (GPS) satellites present
• Radio is switched on

The SD card for CODE 357 (Map navigation) is authorized for the respective radio and can only be used for navigation in that radio.

SD (Secure Digital) map navigation, general 

With SD card navigation, the radio is supported by the following vehicle components:

• Map data and additional navigation-relevant data of the SD card
• GPS signals from the multifunction antenna, with CODE 348 (Emergency call/assist system) via the global positioning system antenna splitter
• 2-D gyro sensor signals from the gyro sensor integrated into the radio
• Operation via the left multifunction steering wheel button group and the right multifunction steering wheel button group
• Operation via the Audio/COMAND control panel
• Operation via the hands-free system microphone
• Audio output via the front vehicle speakers, including audio fadeout, with CODE 810 (Sound system) regulated by sound system amplifier control unit
• Image output and map display on the Audio/COMAND display, additionally in the instrument cluster; the view and the menu display are generated by the radio using the SD map data available
• Traffic Message Channel (TMC) or comparable radio traffic messages via the FM radio tuner integrated into the radio
• Real Time Traffic Data (RTTD) from the tuner unit in vehicles with CODE 536 (SIRIUS satellite radio)
• Updates of map data and navigation software via SD card to Internet-capable PC

Function sequence for SD card navigation 

SD map data is read from the SD card reader integrated into the radio. The GPS signals are received by the radio via a direct line from the multifunction antenna; in vehicles with CODE 348 (Emergency call/assist system), via the global positioning system antenna splitter.

Since GPS operates in the gigahertz range (microwaves) and the signals are weak, the following events may lead to reception interference: Atmospheric interferences (e.g. bad weather, water vapor, fog), multi-path reception due to reflections of the signals (e.g. at building walls) or signal shadowing (e.g. in built-up areas, in tunnels, due to tall buildings or trees).

In the event of a failure of the GPS signals, the radio reverts back to the basic position finding. For basic position finding, the radio evaluates the data of the integrated 2D gyro sensor as well as the wheel speed signals and the selector lever position (whether the reverse gear is engaged) that it receives over the interior CAN (CAN B).

Location errors in position finding, rolling backwards with "circuit 15 OFF" (ignition switched off) or transport of the vehicle falsify the basic position finding. In both instances, the deviation is automatically corrected by the position module integrated in the radio when it receives GPS data.

The control signals from the left multifunction steering wheel button group and the right multifunction steering wheel button group are transferred to the radio as follows:

• Steering wheel electronics
• Steering LIN
• Steering column module control unit
• Chassis CAN 1
• Front SAM control unit with fuse and relay module
• Chassis CAN 2
• Instrument cluster
• Interior CAN

The control signals of the Audio/COMAND control panel are transmitted to the radio via telematics CAN.

The radio receives the voice inputs through the hands-free system microphone via a direct line. The voice output is forwarded by the radio in vehicles except CODE 810 (Sound system) to the speaker system. In vehicles with CODE 810 (Sound system), the radio sends the voice output via MOST to the sound system amplifier control unit. The sound system amplifier control unit amplifies the signals and forwards them to the speaker system.

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The radio switches on the Audio/COMAND display via telematics CAN. The radio transmits the picture signals to the Audio/COMAND display via an LVDS line (Low Voltage Differential Signal). The traffic messages from the integrated FM radio tuners are transferred within the radio.

The traffic messages (RTTD) are received by the multifunction antenna and sent via a direct line to the tuner unit. The tuner unit decodes the signals and sends them over MOST to the audio equipment (except CODE 810 (Sound system)) or to the sound system amplifier control unit (with CODE 810 (Sound system)).

Updates on the SD card takes are downloaded externally on an Internet-capable PC; this is described in the operator's manual.

Electrical function schematic for navigation system function		PE82.61-P-2056-97XAB
Overview of system components, telematics	MODEL 218 as of model year 2015 with CODE 357 (Map navigation) without CODE 509 (Navigation box)	GF82.85-P-9999FQA