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

GF82.85-P-2030CAA Audio Mode, Function
MODEL 207.3 /4
- with CODE (523) MB Audio 20 radio

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) and right multifunction steering wheel button group (S111)
The audio signals are emitted directly at the following speakers by the radio:
- 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)

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). The radio also enables an automatic reception-specific changeover between the antenna amplifiers.

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 single CD drive is integrated into the radio. The single CD drive is used to read in the audio CDs (including in MP3 format) and they are internally processed by the radio. 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.