GF82.85-P-2030CE Audio Mode, Function
GF82.85-P-2030CE Audio Mode, Function
- with CODE (523) MB Audio 20 radio
- with CODE (510) Audio 20 with CD changer
Function requirements, general
^ Circuit 30g On or Circuit 15R On
^ Radio (A2) authorized and operating properly
^ No fault in antenna system (radio function)
The electronic ignition lock control unit (N73) sends the status of circuit 15 to the radio via the interior CAN (CAN B).
Audio mode, general
The audio mode function consists of the following subfunctions:
^ Radio mode function sequence (AM/FM)
^ Audio CD function sequence
The following components are available for control of the audio system:
- Control buttons on the radio
- Audio/COMAND control panel (A40/9)
- Left multifunction steering wheel button group (S110) and right multifunction steering wheel button group (S111)
On vehicles without code (810) Sound system, the audio signals from the radio are routed via direct lines to the following speakers for output:
- Left front door speaker (H4/1)
- Right front door speaker (H4/2)
- Left rear door speaker (H4/3)
- Right rear door speaker (H4/4)
On vehicles with code (810) Sound system, the radio sends the audio signals to the sound system amplifier control unit (N40/3) via the Media Oriented System Transport (MOST). The sound system amplifier control unit processes these signals and routes them, via direct lines, to the following speakers for output:
- Left front door speaker
- Right front door speaker
- Left rear door speaker
- Right rear door speaker
- Center dashboard speaker (H4/27)
- Bass speaker (H4/29) (model 204.0/2)
- Left rear surround speaker (H4/54)
- Right rear surround speaker (H4/57)
On model 204.0 the right rear surround speaker is integrated into the bass speaker. On model 204.9 the audio signals for the rear bass speaker (H4/38) are routed from the sound system amplifier control unit to the rear bass speaker amplifier (N40/9) and from there, via direct lines, to the rear bass speaker.
Radio mode function sequence (AM/FM)
The antennas in the rear window receive signals for the radio frequency bands FM (UKW), AM (MW, LW, SW) and WB (Weatherband).
The following useful signals relevant for the radio reception are modulated onto these signals:
- Music signals
- Speech signals
- Data signals (e.g. traffic information)
The signals are sent via direct lines to the FM rear window antenna amplifier (A2/19) as well as on model 204.0 to the FM, AM and central locking antenna amplifier (A2/18) and on model 204.2/9 to the rear window antenna amplifier 1 (A2/71).
The antenna amplifiers filter the frequencies of the radio frequency bands out of the received signals and amplify them. The amplified signals are then sent via coaxial lines (FM, MW, SW, LW, AM, WB) to the tuner integrated into the radio where they are demodulated and output over the speaker system.
The radio mode (AM/FM) consists of the following subfunctions:
^ Function sequence, AM reception (MW, LW, SW)
^ Function sequence, FM reception (FM)
^ Function sequence, Traffic Announcement (TA) reception (without code (494) USA version)
^ Function sequence, radio data system (RDS) reception (without code (494) USA version) or RBDS reception (with code (494) USA version)
Function sequence, AM reception (MW, LW, SW)
For the MW, LW and SW radio frequency bands, the useful signals are broadcast using amplitude modulation. 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).
Function sequence, FM reception (FM)
For the FM radio frequency band, the useful signals are broadcast using frequency modulation (FM). The FM 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 enables an additional automatic reception-specific changeover between the antenna amplifiers.
Function sequence, Traffic Announcement (TA) reception (without code (494) USA version)
If the radio receives a traffic announcement while a radio station or a CD is playing, the traffic announcement has priority, i.e.:
- The volume of the traffic announcement is increased for radio operation.
- If a CD is playing it is stopped and the traffic announcement made.
Additional function prerequisites for RDS reception (without code (494) USA version) or RBDS reception (with code (494) USA version)
^ RDS or RBDS function activated
^ Radio stations also transmit additional digital information
Function sequence, radio data system (RDS) reception (without code (494) USA version) or RBDS reception (with code (494) USA version)
As well as the normal radio program, many radio stations broadcast additional digital information such as station names, the program type (e.g. pop, culture, etc.) and traffic radio recognition. This information is evaluated by the radio and shown on the Audio/ COMAND display (A40/8). For this purpose, it is necessary to activate the radio functions
Audio CD function sequence
A single CD drive (with code (523) MB Audio 20 radio) or a 6-disk CD changer (with code (510) Audio 20 with CD changer) is integrated into the radio. Audio CDs (including in MP3 format) are read in via the single CD drive or CD changer and processed internally by the radio.
The user interface for controlling the CD functionality (e.g. track selection) and for displaying supplemental information (e.g. title) is on the Audio/COMAND display.
The CD menu and title menu stored in the CD are displayed on the Audio/COMAND display. The scope of functions and menu display depend on the data stored on the CD inserted.
