Radio mode, function

A35/11

A59/1

D2B

A2/12

A1

N80

MFL

A2/6

A2/13

CAN-B

B25/6

X11/4

FM/AM/LW antennas

Antenna signals

IF signal

Diagnosis

CC drive

Radio tuner

Navigation computer

Central computer and graphic signal processing

A40/3

Audio signal processing

Navigation CD drive

Block diagram of COMAND radio system up to 31.8.03, shown on model 220 with code (810) Sound system and code (819) CD changer (6-disk)

D2B Digital data bus

MFL Multifunction steering wheel

IF Intermediate frequency

A40/3 COMAND operating, display and control unit

A59/1 Portable CTEL D2B interface

B25/6 Sound amplifier microphone

N80 Steering column module

X11/4 Data link connector

A1 Instrument cluster

A2/6 CD player with changer (in trunk)

A2/12 Rear window antenna amplifier module

A2/13 Sound amplifier

A35/11 Voice control system control unit

N93/1

N87/5

MOST

A35/11

A2/6

X11/4

N41/1

CC drive

Central computer and graphic signal processing

A40/3

MOST interface

DVD drive

B25/6

A2/82

MOST

Block diagram of COMAND radio system as of 1.9.03, shown on model 215 with code (810) Sound system and code (819) CD changer (6-disk)

MOST Media Oriented System Transport

A2/6 CD player with changer (in trunk)

B25/6 Sound amplifier microphone

N87/5 SDAR control unit

N93/1 Audio gateway control unit

X11/4 Data link connector

A2/82 SDAR antenna

A35/11 Voice control system control unit

A40/3 COMAND operating, display and control unit

 On vehicles as of 1.9.03, all audio signals of the audio components, voice signals as well as the signals of the navigation processor (N41/1) are transmitted via the Media Oriented System Transport (MOST).

 On vehicles as of 1.9.03, the audio gateway control unit (N93/1) is also installed as an interface between the Controller Area Network bus class B (interior) (CAN-B) and the Media Oriented System Transport (MOST). The audio signals are then sent to the audio gateway control unit (N93/1) and output via the vehicle speakers.

The radio menu is activated by pressing the "RADIO" button on the COMAND operating, display and control unit (A40/3).

Radio system function

The antennae in the rear window receive FM, MW and LW high-frequency signals.

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The music, voice or data signals are modulated upon these high frequency signals. The rear window antenna amplifier module (A2/12) filters the radio frequency band frequencies from the received high-frequency signals and amplifies these. The amplified signals are then transmitted to the radio receiver by the rear window antenna amplifier module (A2/12) via a coaxial cable (FM, AM).

The radio receiver demodulates the high frequency signals, in other words it separates the useful information (audible frequencies) from the carrier signal (inaudible).

The demodulated audio signals are amplified and then converted to sound signals by the vehicle speakers.

The COMAND operating, display and control unit (A40/3) also offers the option for requesting information on the current weather conditions at any time. This information is transmitted via the weather channels.

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FM antenna diversity, function

With the antenna diversity function a switchover which is dependent on reception is performed between the 4 FM antenna of the rear window. The function is automatic and is carried out by the rear window antenna amplifier module (A2/12). The radio tuner of the COMAND operating, display and control unit (A40/3) merely generates the "IF" signal which serves the rear window antenna amplifier module (A2/12) as a reference for switching from one FM antenna to the other.

The COMAND operating, display and control unit (A40/3) offers the following options for station selection:

 Manual station search

 Automatic station search with scan function (the stations in the frequency range are each played for 8 s)

 station selection from the memory (10 stations per waveband)

 Station selection by frequency input using the number keypad

Satellite radio reception

Optionally a receiver for satellite radio can be installed. The reception of digital radio stations via satellite can be requested with the SAT-button on the COMAND operating, display and control unit (A40/3). However, the system has to be enabled by a service provider. Once the system has been enabled, up to 224 additional stations can be received.