Navigation, function

S82.61-4518-79

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

 "Circuit 30g ON" status present.

 Transport mode is not active.

 Authorized SD card for CODE EG9 (Navigation) is inserted into the SD card reader of the multimedia connection unit.

 Signals from at least four global positioning system (GPS) satellites are available.

 Radio (Audio/COMAND) is switched on.

 The SD card is authorized for each radio (Audio/COMAND) and consequently it can then not be used in another radio (Audio/COMAND).

SD card navigation (Secure Digital) in general

With SD card navigation the radio (Audio/COMAND) is supported by the following vehicle components:

 Activation via the "NAVI" button in the upper control panel (UCP [OBF]) control unit

 SD-card map data and additional navigation-relevant data, from the multimedia connection unit

 GPS signals from the GPS antenna

 2-D gyro sensor signals from the gyro sensor integrated into the radio (Audio/COMAND)

 Wheel speed signals from the Electronic Stability Program (ESP) control unit

 Operation via the left multifunction steering wheel button group and the right multifunction steering wheel button group

 Operation via the central operating unit (COU [ZBE]) control unit

 Operation via the touchpad control unit

 Operation via the microphone hands-free system (function-specific voice control system)

 Volume control through volume control button in the right lower control panel control unit (UBFR)

 Audio output via the front vehicle speakers, including audio fadeout, with CODE E65 (Burmester surround sound system) regulated by sound system amplifier control unit

 Image output and map display on Audio/COMAND display control unit, also on the instrument cluster (IC [KI])control unit; view and menu display from radio (Audio/COMAND) generated using the SD card data provided for use

 Traffic Message Channel (TMC) or comparable traffic messages via the FM radio tuner integrated into the radio (Audio/COMAND)

 Traffic Message Channel (TMC) or comparable traffic messages over MOST from the Digital Audio Broadcasting (DAB) control unit (with CODE E1D (Digital radio))

 Updates of map data and navigation software via SD card to Internet-capable PC

Function sequence for SD card navigation

The SD card navigation can be activated using the "NAVI" button in the upper control panel (UCP [OBF]) control unit. The radio (Audio/COMAND) receives the control signal from the upper control panel (UCP [OBF]) control unit via the following route:

 Telephone keypad LIN

 Central operating unit (COU [ZBE]) control unit

 Telematics CAN

The radio (Audio/COMAND) accesses the SD card data through a USB line (Universal Serial Bus) to the multimedia connection unit. The GPS signals are received by the radio (Audio/COMAND) over a direct line from the GPS antenna.

 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 (Audio/COMAND) reverts back to the basic position finding. For the basic position finding, the radio (Audio/COMAND) evaluates the data of the integrated 2D gyro sensor as well as the wheel speed signals that it receives via the following route:

 Electronic Stability Program (ESP) control unit

 Chassis CAN

 Gateway for user interface CAN

 User interface CAN

 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 navigation processor integrated in the radio (Audio/COMAND) 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 (Audio/COMAND) via the following route:

 Steering wheel electronics

 Steering LIN

 Steering column tube module (MRM) control unit

 Chassis CAN

 Gateway for user interface CAN

 User interface CAN

 Instrument cluster (KI) control unit

 User interface CAN

The control signals from the central operating unit (COU [ZBE]) control unit or from the touchpad control unit are sent over the telematics CAN to the radio (Audio/COMAND).

The voice input over the hands-free system microphone is received by the radio (Audio/COMAND) over a direct line. The voice output is forwarded by the radio (Audio/COMAND) on vehicles except CODE E65 (Burmester surround sound system) to the speaker system. On vehicles with CODE E65 (Burmester surround sound system) the radio (Audio/COMAND) sends the voice output over MOST to the sound system amplifier control unit. The sound system amplifier control unit amplifies the signals and forwards them to the speaker system.

 More detailed information on the speaker system is available in the "Speaker output function" document.

The volume can be adjusted during voice output using the volume control button in the right lower control panel control unit (UBFR). The control signal is forwarded by the lower control panel control unit to the radio (Audio/COMAND) via the following route:

 Telephone keypad LIN

 Central operating unit (COU [ZBE]) control unit

 Telematics CAN

On vehicles with CODE E65 (Burmester surround sound system) the radio (Audio/COMAND) forwards the volume setting over MOST to the sound system amplifier control unit.

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

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