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GF82.60-P-3020GQ Digital Audio Broadcasting (DAB), Function



GF82.60-P-3020GQ Digital Audio Broadcasting (DAB), Function
- with CODE (537) Digital radio


Function requirements, general
^ Status of circuit 30g On or circuit 15R On
^ System is authorized and operating properly
^ DAB/L-band antenna (A2/93a7) in the roof antenna module (A2/93), left antenna amplifier module (A2/64) (model 164) or right antenna amplifier module (A2/65) (model 251) and the relevant antenna structures are operating properly

Depending on the equipment installed one of the following control units will be installed, hereafter referred to as the "audio unit":
- Radio (A2) (with code (510) Audio 20 with CD changer)
- Radio and navigation unit (A2/56) (with code (525) MB Audio 50 APS radio or with code (511) Audio 50 APS with DVD changer)
- COMAND operating, display and controller unit (A40/3) (with code (527) COMAND APS with single DVD drive (with navigation) or code (512) COMAND APS with DVD changer)

Digital Audio Broadcasting (DAB), general
The DAB function makes it possible to transfer a number of programs via a single frequency; these programs are referred to as an "Ensemble". Up to 64 frequencies are available fro DAB; in Great Britain, up to 7 of these frequencies can be received simultaneously; as a rule, this number is 2 to 3 frequencies. An "ensemble" can consist of up to 12 programs.
Each program can have subprograms (e.g. news announcement, summary of events, etc.). Only the "ensemble name", not the frequency, is displayed for the individual "ensembles".

DAB is a digital radio mode which eliminates the usual "FM/AM noise". However, short-term interruptions in reception of the "ensembles" are possible, because with DAB only two reception states are possible "Complete reception" or "No reception". The Digital Audio Broadcasting control unit (N87/3) allows reception of "Ensembles" in DAB format. Control of the DAB functions is accomplished on the "audio unit". The information and displays required for control are output on the "audio unit" display.

Operating instructions
DAB can be operated using the following components:
- Left multifunction steering wheel button group (S110) and right multifunction steering wheel button group (S111)
- Control buttons on "Audio unit"
- Voice control of the voice control system (VCS [SBS]) (with code (511) Audio 50 APS with DVD changer or with code (527) COMAND APS with single DVD drive (with navigation) or code (512) COMAND APS with DVD changer)

It is only possible to select stations in the memory list or station list with the multifunction steering wheel button groups. The "Ensemble" can only be changed using the control buttons at the "audio equipment" or the VCS [SBS] voice control.

Function sequence for DAB radio
- The DAB/L-band antenna in the roof antenna module receives the DAB L-band signals for the local broadcasts, usually from conurbation stations.
- The left antenna amplifier module (model 164) or right antenna amplifier module (model 251) receives the DAB band III signals for large area broadcasting via the antenna structures in the respective side window, usually from stations with a long range or from national stations.

The signals are forwarded to the Digital Audio Broadcasting control unit using coaxial cables. The Digital Audio Broadcasting control unit decodes the signals and transfers these in the form of PCM (Pulse Code Modulation) signals via the Media Oriented System Transport (MOST) to the "Audio unit".

On vehicles with code (810) Sound system, the Digital Audio Broadcasting control unit transfers the PCM signals for audio output, via the MOST, to the sound system amplifier (N40/3). From there the PCM signals for audio output are output via direct lines over the following speakers:
- Speaker Left front door (H4/5)
- Right front door speaker (H4/6)
- Left rear door speaker (H4/3)
- Right rear door speaker (H4/4)
- Center cockpit speaker (centerfill) (H4/27)
- Subwoofer speaker (H4/29)
- Left front door tweeter (H4/33)
- Right front door tweeter (H4/34)
- Left rear door tweeter (H4/35)
- Right rear door tweeter (H4/36)
- Left rear surround speaker (H4/54)
- Right rear surround speaker (H4/57)

The audio signal for the subwoofer speaker travels via MOST from the Digital Audio Broadcasting control unit to the sound system amplifier and from there, via the subwoofer amplifier (N40/9), along direct lines to the subwoofer speaker.

In vehicles without code (810) Sound system, the Digital Audio Broadcasting control unit transfers the PCM signals for audio output over the MOST to the "Audio unit". From there the PCM signals for audio output are output over discrete lines on the following speakers:
- Left front door speaker
- Right front door speaker
- Left rear door speaker
- Right rear door speaker
- Left front door tweeter
- Right front door tweeter
- Left rear door tweeter
- Right rear door tweeter





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