GF82.85-P-2030CWC Audio Mode, Function

GF82.85-P-2030CWC Audio Mode, Function

Function requirements
^ Status "circuit 30 ON" or "circuit 15R ON"
^ System radio authorized and in working order
^ No errors in the antenna system (radio function)
^ Data CD inserted
^ A radio broadcast data system (RBDS) station is tuned in and the RBDS function activated
^ The radio station broadcasts additional digital information

Function sequence for audio mode in general
The audio mode is made up of the following subfunctions:
^ Function sequence for radio mode (AM/FM)
^ Function sequence for audio CD and MP3 (on CD)
^ Function sequence for the satellite digital audio radio (satellite radio) (SDARS), with code (536) SIRIUS satellite radio

Operating instructions
Audio functions are operated or selected or adjusted using the following components:
^ Left multifunction steering wheel button group (S110)
^ Group of buttons on right of multifunction steering wheel (S111)
^ Audio/COMAND control panel (A40/9)
^ Control buttons on radio (A2)

Function sequence for radio mode (AM/FM)
The antennas in the rear window receive high frequency (HF) signals for the FM and AM (MW, LW) radio frequency bands. The following useful signals relevant for radio reception are modulated onto these HF signals:
^ Music signals
^ Voice signals
^ Data signals (e.g. weather information)

The HF signals are routed over discrete lines to the FM, AM and CL [ZV] antenna amplifier (A2/18) as well as the rear window antenna FM antenna amplifier (A2/19). These two amplifiers filter the frequencies of the radio frequency bands out of the received HF signals and amplify them. The amplified signals are then transmitted over coaxial lines (FM, AM) to the tuners integrated into the radio where they are demodulated. The demodulated audio signals for vehicles with code (810) Sound system are routed from the radio over the Media Oriented System Transport (MOST) to the sound system amplifier control unit (N40/3) and finally amplified.

Audio output then takes place over discrete lines through the following speakers:
^ Left front door speaker (H4/1)
^ Right front door speaker (H4/2)
^ Left rear door speaker (H4/3)
^ Right rear door speaker (H4/4)
^ Center instrument panel speaker (H4/27)
^ Bass speaker (H4/29)
^ Left rear surround speaker (H4/54)
^ Right rear surround speaker (H4/57)

For vehicles except code (810) Sound system, audio output takes place over discrete lines directly from the radio via the following speakers:
^ Left front door speaker
^ Right front door speaker
^ Left rear door speaker
^ Right rear door speaker
^ Center instrument panel speaker

The function sequence for radio operation is made up of the following subfunctions:
^ AM tuner (MW, LW, SW) function
^ FM double tuner with phase diversity (FM) function
^ Radio broadcast data system (RBDS)

AM tuner (MW, LW) function
For the MW and LW radio frequency bands the useful signals are transmitted by means of amplitude modulation (AM). The AM tuner integrated into the radio demodulates these signals. In other words, it separates the useful signals (audible frequencies) from the carrier signal (inaudible).

FM double tuner with phase diversity (FM) function
For the FM radio frequency band the useful signals are transmitted by means of frequency modulation (FM). The FM double tuner integrated into the radio demodulates these signals. In other words, it also separates the useful signals (audible frequencies from the carrier signal (inaudible).

The radio also performs a reception-specific switchover between the two antenna amplifiers. This function runs automatically.

RBDS function
Digital, inaudible information such as the name of the station, type of program (PTY) (e.g. pop, classic) are evaluated by the radio and displayed on the audio/COMAND display (A40/8).

Function sequence for audio CD and MP3 (on CD)
A CD player is integrated into the radio. The CD drive reads in the audio CDs (also in MP3 format) and they are internally processed by the radio. The user navigation for controlling the CD functionality (e.g. track selection) and for displaying any supplemental information (e.g. track) is shown on the audio/ COMAND display. For vehicles with code (810) Sound system, data exchange takes place between the radio and the sound system amplifier control unit over the MOST.

The audio output is then forwarded directly over discrete lines by the radio to the following speakers:
^ Left front door speaker
^ Right front door speaker
^ Left rear door speaker
^ Right rear door speaker
^ Center instrument panel speaker
^ Bass speaker
^ Left rear surround speaker
^ Right rear surround speaker

For vehicles except code (810) Sound system, audio output takes place over discrete lines directly from the radio via the following speakers:
^ Left front door speaker
^ Right front door speaker
^ Left rear door speaker
^ Right rear door speaker
^ Center instrument panel speaker