GF82.62-P-3100-04Q Sound Amplifier, Function
GF82.62-P-3100-04Q Sound Amplifier, Function
- with CODE (810) Sound system
The data exchange between the sound amplifier (A2/13) and radio (A2) or the COMAND operating, display and control unit (A40/3) takes place over the Digital Data Bus (D2B). All the control information and audio signals (radio, cassette, CD, navigation voice output) are transmitted through the D2B.
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 conventional analog filters digital filters exhibit the following several distinct advantages:
^ The filter parameters (sound settings) do not alter during the course of time. This means exact reproducibility of all settings.
^ Lower noise.
^ The cost of components is reduced considerably as the filter 6parameters 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 6 high-level stages is constantly monitored and regulated such that distortion is kept to a minimum.
Sound processing with high resolution
All 6 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 speed-dependent volume control (SDV) function can be individually set.
"Bose Fader" function
The "Bose Fader" maintains the full sound quality, even if the sound playback is faded more to the rear or to the front. 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 "Bose Fader" ensures that the full bass sound is reproduced.
"Baby Sleep" function
When the system is regulated to the front, the bass playback remains fully operative during the first 9 regulation steps. Only at position 10 is the bass completely faded out, whereupon sound components are no longer heard from the rear area (including bass), i.e. from the loudspeakers behind the B-pillar.
Suppression of background noise
A dynamically controlled limiter function monitors the output signal and adapts the level so that a maximum of usable sound pressure is achieved while distortions are largely suppressed.
Dynamic Range Optimization (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.
The following speakers are actuated by the 6 signal outputs:
^ Left front door speaker/max. 25 W
^ Left rear door speaker/max. 25 W
^ Right front door speaker/max. 25 W
^ Right rear door speaker/max. 25 W
^ Center Fill speaker/max. 25 W
^ Rear speaker (subwoofer)/max. 100 W
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 the D2B and can be read out via the diagnosis line.
In order to test the D2B system when installing and to localize 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).