GF82.62-P-3100-04QM Sound Amplifier, Function
GF82.62-P-3100-04QM Sound Amplifier, Function
- with CODE (810) Sound system
- except CODE (498) Japanese version
- except CODE (494a) USA version
The data is exchanged between the sound amplifier (A2/13) and the other audio components over the Media Oriented System Transport (MOST). All the control information and audio signals (radio, CD, navigation voice output) are transmitted over this fiber optical cable.
Signal processing
In order to make possible the diverse adjustments to the sound, the sound amplifier (A2/13) has a digital signal processor which carries out the complete signal filtering. In comparison to analog filters, digital filters have the following distinct advantages:
^ The filter parameters (tone settings) do not change over the course of time. This means that all settings are exactly reproducible.
^ Lower noise occurs.
^ The cost of components is reduced considerably as the filter parameters are adjusted by the software and not by varying component values (resistances, capacitances or inductivities). The number of possible filter settings also increases as a result.
Noise suppression
The output level of the six 8 high-level stages is constantly monitored and regulated such that distortion is kept to a minimum.
Sound processing with high resolution
All 8 amplifier channels are provided with a frequency response characteristic which is individually designed for the vehicle acoustics. In order to achieve this, digital filters of a higher order are used.
Sound optimization
Further sound optimizations and effects such as voice-emphasized, driver-optimized, or room sound can be called up. Bass, treble, volume, balance, fader and the dynamic loudness function can be individually set.
Bose fader function
The Bose fader should maintain the full sound quality, even if the sound playback is controlled more to the front or to the back. As the bass is generated at the back on the rear shelf, without the Bose fader the bass would be faded out, the more "fading" (regulated) is done to the front. The full bass playback is retained with the Bose fader
Baby Sleep function
When the system is regulated to the front, the bass playback remains fully operative during the first 9 regulation steps. Only in position 10 is the bass completely faded out and no more sound shares come from the rear area (no bass either), i.e. from the loudspeakers behind the B-pillars.
Suppression of disturbing noise
A dynamically controlled limiter function monitors the output signal and adapts the level so that a maximum permissible sound pressure is achieved. Any distortions are largely suppressed.
Dynamic Range Optimizer (DRO)
The noise level inside the vehicle is measured using the sound amplifier microphone (B25/6) which is connected directly to the sound amplifier (A2/13).
The music output is constantly adapted so that the influence of superimposed driving noise is compensated. To do this the sound amplifier (A2/13) must detect which signals of the measured level are driving noise and which are audio signals. This is done through comparing the sound amplifier (A2/13) output signal with the measured signal.
Diagnosis sound amplifier
The sound amplifier (A2/13) makes available the following messages relevant to diagnosis:
^ Operating status
^ Undervoltage
^ Internal fault in the sound amplifier (A2/13)
The messages are transmitted to the COMAND operating, display and control unit (A40/3) or the radio (A2) via MOST and can be read out via the data link connector (X11/4).
In order to test the MOST system when installing and to pinpoint any fault sources or in order to be able to reproduce faults which have occurred during operation, a diagnosis mode has been implemented in the sound amplifier (A2/13).