Quote:
Originally Posted by gblaue
Engine RPM
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The audio amplifier is also responsible for operation of active noise cancellation. Refer to Active Noise Cancellation Description and Operation for more information.
Active Noise Cancellation Description and Operation (NKC with UQA)
The entertainment system on this vehicle may have several different configurations. To determine the specific configuration of the vehicle, please see the Service Parts ID Label, and refer to RPO Code List.
The main components of the Active Noise Cancellation system are:
•2 microphones in the vehicle door trim.
•Active Noise Cancellation electronics and software integrated into the audio amplifier
•The vehicle speaker system, connected to the amplifier, to output the desired cancellation frequencies
The Active Noise Cancellation system is operational under the following conditions:
•The amplifier has passed all self diagnostic checks
•All doors are closed
•Battery voltage is between 9.5 V and 16 V
•The vehicle cabin temperature is less than 140°F (60°C)
•Engine speed is between 550 and 3000 RPM
The Active Noise Cancellation system is a method used to reduce the perception of certain undesirable sounds generated by the engine into the vehicle cabin. The systems uses microphone and engine speed signals, software integrated into the amplifier, and the vehicle speakers to determine and generate the correct frequencies needed to achieve the desired reduction.
Two microphones are located in the door trim to monitor noise/sounds in the vehicle cabin, and are directly connected to the amplifier. The amplifier also receives engine speed (RPM) via serial data. The amplifier processes these inputs to determine the frequency of the undesirable sound. The amplifier then calculates the appropriate cancellation frequency and outputs a cancellation signal (audio tone) to the vehicle speakers to reduce the perception of undesirable sounds by the vehicle occupants so the vehicle cabin appears quieter and without vibration.