Feedforward ANC Delay Compensation for Lower Computing Load
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Solution Overview
Problem
Feedforward active noise control systems require significant computing power due to the need for standard least-mean-square algorithms and adequate hardware, necessitating a reduction in computational resources.
Innovation Solution
Implementing compensation delays in the signal paths of the ANC system, including pre-system, post-system, or distributed delays, to align latency differences between primary and secondary paths, allowing for reduced computing power while maintaining effective noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard least-mean-square algorithms are used in feedforward ANC systems, then noise cancellation performance is improved, but computing power requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing filter coefficients for different latency conditions. The system prepares multiple sets of coefficients corresponding to different delay values, allowing the ANC algorithm to quickly switch between them based on the actual latency measured in the signal path, avoiding real-time computational complexity while maintaining optimal noise cancellation performance
Solution Approach 2:
The patent changes the parameter of filter coefficients based on measured latency values. By adjusting the coefficients according to pre-calculated values that correspond to specific latency conditions, the system adapts to different runtime differences without requiring complex real-time computations, thus reducing computing power requirements while preserving cancellation effectiveness
2Productivity
If compensation delays are added to align latency differences, then noise cancellation efficiency is improved, but system complexity increases
Solution Approach 1:
The patent introduces compensation delays as intermediary elements in the signal path. These delays act as mediators that align the timing between the reference signal and the error signal, ensuring that the adaptive filter processes synchronized data. This simple timing alignment mechanism improves cancellation efficiency without requiring complex system modifications
Solution Approach 2:
The patent segments the ANC system into distinct functional blocks with measurable latency characteristics. By dividing the system into reference signal path, error signal path, and filter processing sections, each with identifiable delay values, the system can independently measure and compensate for latency differences in each segment, improving efficiency through targeted delay adjustment rather than system-wide complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The implementation of compensation delays enhances ANC system performance by optimizing FIR filter usage, reducing waste and improving noise cancellation efficiency without compromising on computing resources.
Implementation Method 1
Active noise control (ANC) is used to generate sound waves that destructively interfere with undesired sound waves. The destructively interfering sound waves may be produced by a transducer, such as a loudspeaker, to combine with the undesired sound waves.
Data Source
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AI summary
Sound reduction includes receiving a reference signal corresponding to undesired sound present in the target space, and producing, based on the reference signal, a cancelling signal representative of the undesired sound present in the target space. Sound reduction further includes producing, based on the cancelling signal, sound to destructively interfere with the undesired sound present in the target space, and delaying at least one of the reference signal and the cancelling signal to reduce or compensate for runtime differences between signal paths that transfer the reference signal to the target space.