Audio mode, function - GF82.85-P-2030CWB

MODEL 204.0 with CODE (523) MB Audio 20 radio 

MODEL 204.2 with CODE (523) MB Audio 20 radio 

Function requirements 

• Status "circuit 30 ON" or "circuit 15R ON"
• The radio is authorized and in perfect working order
• No fault in antenna system (radio function)
• Data CD is inserted
• A radio data system (RDS) station is set and the RDS function activated
• Radio stations also transmit additional digital information
• Traffic Announcement (TA) function set on the radio

General audio mode function sequence 

The audio mode consists of the following component functions:

• Radio mode function sequence (AM/FM)
• Function sequence for audio CDs as well as MP3 (on CD)

Operating instructions 

The audio functions can be controlled or selected 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)

Radio mode function sequence (FM/AM) 

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 the radio reception are modulated onto these HF signals:

• Music signals
• Speech signals
• Data signals (e.g. TA signals for current traffic information)

These HF-signals are sent over discrete lines to the FM, AM and central locking antenna amplifier (A2/18) (model 204.0) or rear window antenna amplifier 1 (A2/71) (model 204.2) as well as to the antenna amplifier for the rear window FM antenna (A2/19). These amplifiers filter the frequencies of the radio frequency bands out of the received HF signals and amplify them. The amplified signals are then sent via coaxial cable (FM, AM) to the tuner integrated in the radio where they are demodulated and finally amplified.

The radio's audio output is emitted at the speakers via discrete lines. The following speakers are actuated:

• 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)

The radio mode function sequence consists of the following component functions:

• AM tuner (MW, LW, SW) function
• FM dual tuner with phase diversity (FM)
• Traffic Announcement (TA) function, traffic information (FM only)
• Radio Data System (RDS) function (FM only)

AM tuner (MW, LW) function 

For the MW and LW 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 dual tuner with phase diversity (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 two antenna amplifiers. This function runs automatically.

Traffic Announcement (TA), traffic information function 

If the radio receives a traffic announcement (TA) while a radio station or a CD is running, the traffic announcement takes 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.

RDS function 

Digital, inaudible information such as station names, types of program (PTY) (e.g. pop, classic) and traffic information recognition is evaluated by the radio and shown on the Audio/COMAND display (A40/8).

Function sequence for audio CDs as well as MP3 (on CD) 

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

Audio output is sent directly by the radio via discrete lines to the following speakers:

• Left front door speaker
• Right front door speaker
• Left rear door speaker
• Right rear door speaker
• Center instrument panel speaker

	Electrical function diagram for radio	Except code (494) USA version	PE82.60-P-2050-99FAA
	Radio control panel component description	A2	GF82.60-P-3116CW
	Speaker system, component description	H4/1, H4/2, H4/3, H4/4, H4/27 Except code (810) Sound system	GF82.62-P-4220CW
	Cockpit central display, component description	A40/8 Entry	GF54.30-P-6100CW
	Rear window antenna module, component description	A2/19	GF82.62-P-3131CW
	Rear window antenna component description		GF82.62-P-3123CW
	Side window antenna, component description	Type 204.2 With CODE (889) Keyless Go Left	GF82.62-P-3130CSL
		Type 204.2 With code (537) Digital radio Right	GF82.62-P-3130CSR
	Antenna amplifier module, component description	A2/18	GF82.62-P-3003CW
	Front central operating unit, component description	A40/9	GF54.21-P-4500CW