Sound Generator Control Unit Basic Function - GF82.27-P-9890A

Model All (CAR) 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 
  • Noise reduction in vehicle interior
  • Noise simulation in vehicle interior
  • Noise simulation for vehicle surroundings

General 

The sound generator control unit forms the engine and driving noise as perceived in the vehicle interior. This is achieved primarily through the reduction of disturbing noise contributions and the simulation of missing noise contributions (e.g. with hybrid and electric vehicles). The signals are emitted through the speaker system.

In hybrid and electric vehicles, the sound generator control unit also actuates the sound generators for external noise.

The sound generator control unit is used on vehicles as from telematics device version NTG 7.

Function requirements: 

• Circuit 30t, for driving noise reduction and for compensation of missing engine noise
• Engine running, for engine noise reduction and actuation of sound generators for external noise

Function 

Noise reduction in vehicle interior 

The sound generator control unit reduces engine and driving noises in the vehicle interior by generating counter signals (inverted signals).

This includes:

• Receiving and evaluating from acceleration sensors at the wheels and axles for driving noise reduction.

The acceleration sensors supply a reference signal from which the rolling noises are derived.

• Receiving and evaluating engine data via CAN interface for engine noise reduction.
• Receiving and evaluating microphone signals.

The transmission path in the vehicle interior is monitored using microphones.

• Generating the forwarding the counter-signals over the audio bus. Noise simulation in vehicle interior 

  With hybrid and electric vehicles as well as for some combustion engines, the sound generator control unit compensates for the low acoustic feedback from the motor. This includes:

• Receiving and evaluating engine data via the CAN interface
• Generating and forwarding simulated engine noise signals and acoustic feedback via audio bus
• Generating and forwarding actuation signals for steering wheel vibrations

Noise simulation for vehicle surroundings 

The actuation of the sound generators for the exterior noise ensures that the vehicles are acoustically perceptible at low speeds (up to 30 km/h). At speeds of more than 30 km/h, the rolling noises and wind noises are loud enough that the vehicle can be perceived.

To control the sound generators for exterior noise, the sound generator control unit reads in the speed signal and the accelerator pedal position.