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

GF82.85-P-2030FLB Audio Mode, Function
- with CODE (523) MB Audio 20 radio


Function requirements
^ Circuit 30g ON
^ A radio data system (RDS) station is set and the RDS function activated
^ The radio station also transmits additional digital information

General
The Audio mode consists of the following function sequences which can be activated with the menu item Audio
^ Radio mode function sequence (AM/FM)
^ Function sequence for audio CD

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

Function sequence for radio mode (AM/FM)
The antennas in the rear window receive audio signals for the FM and AM (MW, LW and SW) radio frequency bands. The following useful signals relevant for the radio reception are modulated onto these audio signals:
- Music signals
- Speech signals
- Data signals (e.g. traffic information)

The signals are sent over direct lines to the FM 1, AM, CL [ZV], and KEYLESS-GO antenna amplifier (A2/18) and to the FM 2 and DAB antenna amplifier (A2/19). 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 tuners integrated into the radio where they are demodulated.

The demodulated audio signals are output directly at the following speakers by the radio:
- Left front door speaker (H4/1)
- Left front door tweeter (H4/1h1)
- Right front door speaker (H4/2)
- Right front door tweeter (H4/2h1)
- Left rear door speaker (H4/3)
- Left rear door tweeter (H4/3h1)
- Right rear door speaker (H4/4)
- Right rear door tweeter (H4/4h1)

The function sequence for radio mode also consists of the following subfunctions:
^ Function sequence for AM tuner (MW, LW, SW)
^ Function sequence for FM double tuner with multipath reception (FM)
^ Function sequence for RDS
^ Function sequence for Radiotext+ (as of 1.6.2010)

Function sequence for AM tuner (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).

FM double tuner function with multipath 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 reception-specific changeover between the antenna amplifiers. This function runs automatically.

Function sequence for RDS
In addition to the normal radio program, many FM radio stations also transmit additional digital information such as station names, program type (e.g. pop, culture, etc.) and traffic program identification. This information is evaluated by the radio and shown on the Audio/COMAND display (A40/8), when the following preconditions are complied with:
- An RDS station is tuned in.
- The "RDS" function is activated

Function sequence for Radiotext+ (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 functionality (e.g. Track selection) and for displaying supplemental information (e.g. Track) takes place on the Audio/COMAND display.

The CD menu and the Track menu, which are stored on the inserted CD, are shown via the Audio/COMAND display. Because the CD menu and the Track menu are stored on the CD, the functional scope and the menu display are dependent on the actual CD inserted.

The audio signals are emitted directly at the following speakers by the radio:
- Left front door speaker
- Left front door tweeter
- Right front door speaker
- Right front door tweeter
- Left rear door speaker
- Left rear door tweeter
- Right rear door speaker
- Right rear door tweeter