Adaptive Noise Cancellation IC Link Quality Adaptation
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Solution Overview
Problem
Existing distributed adaptive noise cancellation systems in personal audio devices face issues with unreliable digital links, leading to erroneous data transmission and audible artifacts due to the separation of ANC circuitry from transducers.
Innovation Solution
An integrated circuit with a processing circuit that generates an anti-noise signal to counter ambient audio sounds, using a link quality metric to modify the signal generation and adapt to link reliability, ensuring effective noise cancellation even in unreliable communication conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the adaptive ANC circuitry is separated from the transducers to form a distributed ANC system, then the flexibility and modularity of the system is improved, but the reliability deteriorates due to potential digital link failures
Solution Approach 1:
The system continuously monitors the digital link quality and uses this feedback to dynamically adjust the noise cancellation operation. When link quality degrades, the system responds by modifying the adaptive filtering process, such as reducing adaptation rate or freezing coefficients, to prevent degradation of noise cancellation performance while maintaining system stability.
Solution Approach 2:
The noise cancellation system transitions from a static configuration to a dynamic one where the adaptive filter coefficients and operation mode can change in real-time based on link conditions. This allows the system to optimize performance under varying link reliability conditions while maintaining the distributed architecture benefits.
2Reliability
If the digital link operates in unreliable conditions, then the distributed system can still function, but audible artifacts are generated due to erroneous data transmission
Solution Approach 1:
The system prepares for potential link failures by implementing protective measures in advance, such as maintaining valid filter coefficients, using error detection and correction codes, and having fallback operation modes ready. When link errors occur, these pre-prepared measures prevent the generation of audible artifacts by ensuring data integrity or graceful degradation.
Solution Approach 2:
The system converts the potentially harmful effect of link unreliability into a beneficial adaptive mechanism. By monitoring link quality and responding appropriately, the system uses the presence of unreliable conditions as a trigger to switch to more robust operating modes, ultimately improving overall system resilience and preventing artifact generation.
3Reliability
If the link quality metric is monitored and used to modify anti-noise signal generation, then the noise cancellation performance is maintained, but the system complexity increases
Solution Approach 1:
The digital link serves multiple functions: it not only transmits audio data but also carries link quality metrics and control information. The same communication infrastructure is used for both audio transmission and quality monitoring, eliminating the need for separate dedicated monitoring channels and reducing overall system complexity.
Solution Approach 2:
The system monitors its own link quality using the existing communication infrastructure without requiring external monitoring equipment. The link control information is automatically generated and processed by the system itself, enabling self-diagnosis and self-adjustment of the noise cancellation operation based on actual link conditions.
Data Source
AI summary
An integrated circuit may include an output for providing a signal to a transducer including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer, a microphone input for receiving a microphone signal indicative of ambient sounds at the transducer, a link control input for receiving link control information of a communications link coupling the integrated circuit to the transducer and/or a microphone for generating the microphone signal, wherein the link control information includes a link quality metric of the communications link, and a processing circuit comprising a filter having a response that generates the anti-noise signal in conformity with the microphone signal to minimize the ambient sounds at the acoustic output of the transducer, wherein the processing circuit modifies generation of the anti-noise signal responsive to the link quality metric.