Radio mode, function

X11/4

MFL

A35/11

D2B

A2/12

A2/6

A2/13

B25/6

A1

N80

CAN-B

Diagnosis

Navigation computer

Central computer

Navigation CD drive

Audio signal processing

A40/3

FM/AM signals

IF signal

Radio tuner

A34/4

Block diagram for COMAND radio system up to 31.8.03, shown on model 220 with the following equipment:

 Code (810) Sound system

D2B Digital data bus

AM Amplitude modulated

FM Frequency modulated

MFL Multifunction steering wheel

IF Intermediate frequency

A34/4 Telephone interface

A35/11 Voice control system control unit

A40/3 COMAND operating, display and control unit

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

A2/6

MOST

A2/12

N41/1

A35/11

B25/6

CAN-B

A40/3

FM/AM signals

IF signal

A34/4

N93/1

DVD drive

Central computer

A1

N80

Audio signal processing

Interface

MOST

X11/4

Block diagram for COMAND radio system as of 1.9.03, shown on model 215

MOST Media Oriented System Transport

AM Amplitude modulated

FM Frequency modulated

IF Intermediate frequency

A35/11 Voice control system control unit

A40/3 COMAND operating, display and control unit

B25/6 Sound amplifier microphone

N80 Steering column module

N93/1 Audio gateway control unit

X11/4 Data link connector

A1 Instrument cluster

A2/6 CD player with changer (in trunk)

A2/12 Rear window antenna amplifier module

A34/4 Cell phone interface

 On vehicles as of 1.9.03, all audio signals and video signals of the audio/TV components are transmitted by the Media Oriented System Transport (MOST).

 On vehicles as of 1.9.03, the audio gateway control unit (N93/1) is additionally 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 ouput via the vehicle speakers.

Radio system function

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

The antennas in the rear window receive FM, MW and LW high frequency (HF) signals. The music, voice or data signals are modulated upon these high frequency (HF) signals. The rear window antenna amplifier module (A2/12) filters the radio frequency band frequencies from the received high frequency (HF) 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 (HF) signals, in other words it separates the useful information (audible frequencies) from the carrier signal (inaudible).

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

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 intermediate frequency (IF) signal which serves the rear window antenna amplifier module (A2/12) as a reference for switching from on FM antenna to the other.

-----------------------------------------------------------------------------------------

Radio Data System (RDS), function

Many radio stations (FM) transmit, together with the program, additional information such as the station name, type of program (PTY) (e.g. pop, culture, ..), and traffic station identification. This information is evaluated by the COMAND operating, display and control unit (A40/3) and displayed on the screen if the following conditions apply:

 An RDS station is adjusted

 The RDS function is switched on

2-receiver technology, function

A second (integral) radio receiver automatically generates, after switching the COMAND operating, display and control unit (A40/3) on, a list of the FM stations that can be received; this list is continuously updated during operation. This list appears, sorted alphabetically, when the "FM station list" menu is called up. The stations which are displayed can be activated by selecting and confirming.

-----------------------------------------------------------------------------------------

 The station list is only available when the RDS function is activated.

If reception interference occurs while driving, the COMAND operating, display and control unit (A40/3) attempts to receive the selected station on an alternative frequency with the aid of the second receiver. In the event of an improvement in reception, the second receiver automatically switches to this frequency.

 Certain radio channel programs are subdivided into regional programs at certain transmission times. As the COMAND operating, display and control unit (A40/3), as described above, automatically switches to an alternative frequency because of reception interference, this may lead to a change in regional program. If this is not desired, the "Regional program" entry can be activated under the "FM settings" menu.

-----------------------------------------------------------------------------------------

The COMAND system's radio component additionally provides:

 a station list of the currently most powerful FM stations in RDS mode

 an automatic memory for the most powerful MW and LW stations

 a selection of program type (e.g. culture, sport, pop) for FM stations in RDS mode

Station selection options:

 Automatic and manual station search

 scan function (the stations of one waveband are played for
8 s) in all wavebands

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

 Station selection by frequency input via the number block (e.g. 92.2 MHz)

 station selection from the FM station list