Audio gateway control module, function - GF82.62-P-3102-04TJ
The audio gateway control module (N93/1) is the central audio communications interface in the Media Oriented System Transport (MOST).
The control commands are initialized by the COMAND operating, display and control unit (A40/3) and transferred via the MOST ring to the audio gateway control unit (N93/1).
Scope of function:
- AM/FM reception
- Sound processing and amplification
- Implementation of the data exchange between MOST and CAN interior (CAN-B)
- Diagnostic interface
Function conditions:
- Circuit 15R ON
- Authentication positive
- Control module within the specified voltage values
AM/FM reception
If the user selects a particular radio program on the COMAND operating, display and control unit (A40/3), a request is sent to the audio gateway control unit (N93/1) via the MOST ring, whereupon the radio receiver generates a tuned circuit to receive the respective transmission frequency.
Via the radio receiver in the audio gateway control unit (N93/1) the corresponding high-frequency signals in the frequency ranges of FM, MW, LW, SW are filtered out and relayed to the integral audio processing and amplification stage.
Sound processing and amplification
The control commands coming in from the operating units for audio sound and volume control as well as all system component audio signals sent are transmitted via MOST to the audio gateway control module (N93/1).
The integral audio processing stage, Digital Signal Processing (DSP1), digitizes and processes the incoming signals and amplifies them before output to the speakers.
To expand the variation options for sound quality, the audio gateway control unit (N93/1) "Sound" is equipped with the expanded audio processing stage and amplifier stage - Digital Signal Processing (DSP2).
At a rated output of
- 5 40 W at 2 Ω
- 2 70 W at 4 Ω
several speakers are actuated:
- 4 in-door speakers (2 front, 2 rear)
- 1 center speaker
- 2 subwoofers
DRO microphone input
Connection for sound amplifier microphone (B25/6) for automatic vehicle interior noise adaptation "Dynamic Range Optimization" (DRO).
Using the sound amplifier microphone (B25/6), which is connected directly to the audio gateway control unit (N93/1), the noise level in the vehicle interior compartment is measured. The volume of the music output signal is continuously adapted to this noise level. For this purpose, the audio gateway control module (N93/1) must detect which signals of the measured level are driving noise and which are audio signals. This takes place by means of a comparison of the sound amplifier output signal with the measured signal. A simple way of looking at it is to regard the difference in both signals as being the driving noise level.
Interfaces
The audio gateway control unit (N93/1) serves as an interface between MOST and CAN-B date, which are read by the instrument cluster (A1) and placed on CAN-B. They are made available on the Media Oriented System Transport (MOST).
Fault management of the MOST components
The device is the central diagnostic interface for the entire MOST. During operation, the system stores all occurring faults in the nonvolatile memory. These can be read out using
STAR DIAGNOSIS via the diagnostic interface. It is not possible to output faults via the operating unit
The inquiry is initiated via the 16-pin diagnostic connector of STAR DIAGNOSIS under the instrument panel.
Via the central gateway control module (N93) the diagnosis data are transmitted in Keyword Protocol 2000 format directly on the interior CAN. The audio gateway control module (N93/1) recognizes the diagnosis command and converts the incoming data into a message compatible for MOST.
The diagnosis of all MOST components is controlled by the audio gateway control module (N93/1).
Each MOST component has its own diagnostic trouble code memory.