Radio operation, function

Data link connector (X11/4)

D2B interface
portable CTEL

Portable CTEL

CD player
with changer

Telephone antenna
(A2/49a1)

D2B

Traction systems control module (N47)

GPS antenna
(A2/49a2)

Navigation processor with GPS receiver and gyro sensor

Diagnosis

Radio tuner

Traffic data memory

Central processor

Audio
signal processing

CD drive

COMAND operating, display and control module (A40/3)

Vehicle loudspeaker

Hands-free system microphone

Antenna amplifier

(A2/18)

Rear spoiler antenna

(A2/51)

Block diagram for COMAND radio system

The marked components are the major components for operation of the radio.

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

Radio reception, function

The rear spoiler antenna (A2/51) receives high frequency FM and AM signals. The music, voice and/or data signal is modulated upon these high-frequency signals. The FM/AM amplifier (A2/18) filters the frequencies of the radio frequency bands from the high frequency signals received and amplifies them.The amplified signals are then transmitted to the radio receiver integrated in the COMAND operating, display and control module (A40/3) by the FM/AM amplifier (A2/18) via a common co-axial cable (FM, AM).

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.

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Double 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 interference occurs while driving, the COMAND system attempts to receive the selected station on an alternative frequency with the aid of the second receiver. When reception is better the system switches over accordingly.

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 Certain radio channel programs are subdivided into regional programs at certain transmission times. Since COMAND automatically changes to an alternative frequency of the station as described above when interference is present, this can cause a switchover to another regional program. If this is not desired, it is possible to activate the item "regional program" in the menu "FM settings".

Radio Data System (RDS), function

Many radio stations (FM) broadcast digital information in addition to the radio program such as station name, type of program (PTY) (e.g. pop, culture) and traffic radio recognition off. This information is evaluated by COMAND and indicated on the screen when an RDS station is tuned in and the RDS function is activated.

The COMAND system's radio component additionally provides:

 a station list of the FM stations which are momentarily the strongest in the RDS mode

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

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

Possibilities for station selection:

 manual station search

 automatic station search with scan function (stations in one frequency range are played for 8 s)

 station selection from memory (10 stations per frequency range)

 station selection by entering frequency on number pad

 station selection from the FM station list