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

GF82.85-P-2030CAB Audio Mode, Function
MODEL 207.3 /4
- with CODE (510) Audio 20 with CD changer

Function requirements, general
^ Circuit 30g ON

General information on the audio mode
The audio mode function consists of the following component functions:
^ Radio mode function sequence (AM/FM)
^ Function sequence for audio CD
The following components are available for control of the audio system:
- Control buttons on the radio (A2)
- Audio/COMAND control panel (A40/9)
- Left multifunction steering wheel button group (S110) or right multifunction steering wheel button group (S111)
On vehicles without code (810) Sound system, the audio signals are output directly by the radio to the following speakers:
- Left door tweeter (H4/1h1)
- Left door bass speaker (H4/1h2)
- Right door tweeter (H4/2h1)
- Right door bass speaker (H4/2h2)
- Left rear tweeter (H4/3h1)
- Left rear bass speaker (H4/3h2)
- Right rear tweeter (H4/4h1)
- Right rear bass speaker (H4/4h2)
On vehicles with code (810) Sound system, the audio signals are sent by the radio over the Media Oriented System Transport (MOST) to the sound system amplifier control unit (N40/3) and then finally amplified. The audio signals are directly output by the sound system amplifier control unit to the following speakers:
- Door tweeter
- Door bass speaker
- Rear tweeter
- Rear bass speaker
- Center dashboard speaker (H4/27)
- Rear shelf bass speaker (H4/29)
- Left rear surround speaker (H4/54)
- Right rear surround speaker (H4/57)

Function sequence for radio mode (AM/FM)
The antennas in the rear window (model 207.3) receive audio signals for the FM and AM (MW, LW, SW) radio frequency bands).
For model 207.4 the radio frequency bands FM are received over the antenna in the front window. Reception of the AM frequency bands takes place for model 207.4 via the AM soft top antenna (A2/111) with a closed soft top and via the rear side paneling AM antenna with an open soft top.
The following useful signals, relevant for radio reception, are modulated onto these audio signals:
- Music signals
- Speech signals
- Data signals (e.g. traffic information)
Model 207.3
The FM signals are sent over direct lines to the FM, AM and CL [ZV] antenna amplifier (A2/18) and are routed to the rear window antenna FM antenna amplifier (A2/19).
Model 207.4:
The FM signals are sent over direct lines to the FM, AM and CL [ZV] antenna amplifier (A2/55) and are routed to the antenna amplifier TV 3, FM2 and DAB band III (A2/54). The AM signals are sent on via the AM amplifier with selection switch (A104/2) by means of a direct line to the FM, AM and ZV antenna amplifier.
The AM signals from the AM soft top antenna are also amplified by the AM amplifier (A104/1).
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 cables to the tuner integrated in the radio where they are demodulated and output over the speaker system.
The radio mode (AM/FM) function is made up of the following subfunctions:
^ Function sequence for AM reception (MW, LW, SW)
^ Function sequence for FM reception
^ Function sequence for radio data system (RDS) reception
^ Function sequence for Radio text+ (as of 1.6.2010)

Function sequence for AM reception (MW, LW, SW)
For the MW, LW and SW radio frequency bands, the useful signals are broadcast using 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).

Function sequence for FM reception
For the FM radio frequency band, the useful signals are transmitted using frequency modulation. 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).

Additional function requirements for RDS reception
^ RDS function activated
^ Radio stations also transmit additional digital information

Function sequence for RDS reception
Apart from the normal radio program, many radio stations (FM) transmit additional digital information such as station names, program type (e.g. pop, culture) and traffic program identification.
This information is evaluated by the radio and shown on the Audio/ COMAND display (A40/8). The functionality in the radio has to be activated for this purpose.

Function sequence for Radio text+ (as of 1.6.2010)
During FM radio operation, additional information on the program can be shown on the Audio/COMAND display. For this, the "Info" softkey in the function bar must be pressed.

Function sequence for audio CD
A CD changer is integrated into the radio. The CD drive enables the audio CDs (also in MP3 format) to be read in, internally processed by the radio and output over the speaker system.
The menu navigation for controlling the CD functions (e.g. track selection) and for displaying supplemental information (e.g. track) is on the Audio/COMAND display.
The CD menu and the Track menu, which are stored on the inserted CD, are shown on the Audio/COMAND display. The function scope and the menu display are dependent on the data stored on the inserted CD.