Radio mode function

Antenna booster
Top left rear window
(A2/8)

FM2, 3

Navigation processor with
GPS receiver and gyrosensor

Diagnostic test connector (X11/4)

diagnosis

Traffic data
memory (A2/43)

Central
processor

Antenna booster
Bottom left rear window
(A2/24)

IF signal

FM/AM signals

Radio tuner

Audio
signal processing

FM1/AM signals

Instrument cluster (A1)

Multifunction steering wheel

Vehicle loudspeaker

Activation

FM1, AM

CD drive

Operating ,
display and
control unit
COMAND
(A40/3)

AF signals

CAN (A40/3-A1)

COMAND radio system block circuit diagram, depicted with the type 210.0 antenna system with the following equipment:

 Sound system (code 810)

The marked components are those which are significantly involved in the operation of the radio.

Abbreviations

AM Amplitude-modulated

CAN B Interior CAN

FM Frequency-modulated

Amplifier for sound system (N40/3)

COMAND radio system block circuit diagram, depicted with the type 210.0 antenna system with the following equipment:

 Sound system (code 810)

The marked components are those which are significantly involved in the operation of the radio.

Abbreviations

AM Amplitude-modulated

FM Frequency-modulated

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

Radio reception function

 The antenna system versions differ depending on the vehicle model. The following description refers, as an example, to the model 208 (except for 208.4) and 210 (except for 210.2) antenna system.

The antennae in the rear window receive FM, MW and LW
high-frequency signals. The music, voice and/or data signal is modulated upon these high-frequency signals. The two antenna boosters on the top left/bottom left rear window (A2/8, A2/24) filter the radio frequency band frequencies out of the high frequency signals which are received, and amplify these. The amplified signals are then transmitted by the antenna booster at the lower left rear window (A2/24) via a joint coaxial lead (FM, AM) to the radio receiver (integrated in the COMAND operating, display and control unit (A40/3)).

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The radio receiver demodulates the high-frequency signals, i.e. it separates the useful information (audible frequencies) from the carrier signal (inaudible). The demodulated audio signals are amplified and converted into sound signals by the vehicle loudspeakers.

FM antenna diversity function (not in model 208.4, 210.2)

In the case of the antenna diversity function, receipt-dependent switching is carried out between the FM antennae of the rear window. The function is automatic and is carried out by the antenna booster at the lower left rear window

(A2/24). The radio tuner of the COMAND operating, display and control unit (A40/3) merely generates the IF signal (Intermediate Frequency), which serves the antenna booster as a reference for switching the FM antenna.

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Dual receiver technology function

After COMAND has been switched on, a second (integrated) radio receiver automatically generates a list of the received FM stations; this 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 via selection and confirmation.

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

If reception becomes disturbed during driving, COMAND attempts, with the aid of the second receiver, to receive the selected station on an alternative frequency. Switching is carried out accordingly in the event that reception improves.

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 Certain radio channel programs are subdivided into regional programs at certain transmission times. As COMAND, as described above, automatically switches to an alternative station frequency if reception becomes disturbed, this may also lead to a change in the regional program. If this is not desired, the "Regional program" entry can be activated under the "FM settings" menu.

Radio Data System (RDS) function (except for )

In addition to the radio program, many radio stations (FM) also transmit additional digital information, such as the name of the station, the type of program (PTY) (e. g. pop, culture) and

traffic radio detection.

This information is evaluated by COMAND, and is displayed on the screen if:

 an RDS transmitter is set and

 the RDS function is switched on.

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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/LW stations

 program type selection (PTY, e.g. culture, sport, pop) in the case of FM stations in RDS mode

 for  weatherband program selection
(current weather reports)

Station selection options:

 manual station search

 automatic station search with scan function
(the stations of one waveband are played for 8 s)

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

 station selection by inputting the frequency via the number keypad (e. g. 92.2 MHz)

 station selection from the FM station list