Dual Echo Cancellers for Mobile Audio Signal Processing
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Solution Overview
Problem
Conventional audio processing systems in mobile devices face challenges in efficiently handling a wide range of audio signals with varying qualities, such as polyphonic ringers, voice, and high-quality audio, due to the complexity of operational requirements and diverse communication technologies, leading to limitations in echo cancellation and user experience.
Innovation Solution
A dual echo canceller system comprising an active echo canceller and an adaptive echo canceller, where filter coefficients are copied from the adaptive echo canceller to the active echo canceller based on convergence, utilizing normalized block least mean squares (NBLMS) and linear predictive coding (LPC) for effective echo cancellation, adapting to changes in echo paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single echo canceller is used to handle diverse audio signals, then device complexity is reduced, but echo cancellation performance deteriorates due to inability to adapt to different audio qualities and environments
Solution Approach 1:
The echo cancellation system is divided into two independent echo cancellers: a first echo canceller for acoustic echo cancellation and a second echo canceller for network echo cancellation. Each canceller is specialized for its specific type of echo, allowing optimized performance for different audio signals and environments without the complexity of a single universal system.
Solution Approach 2:
The dual echo canceller system provides multi-functionality by handling both acoustic echo and network echo simultaneously. The system can process diverse audio signals including polyphonic ringers, voice, and high-quality audio through the coordinated operation of both cancellers, making it universally applicable to various audio scenarios.
2Measurement precision
If echo cancellation is optimized for specific audio sources, then cancellation precision improves, but adaptability to different audio qualities deteriorates
Solution Approach 1:
The system segments the echo cancellation function into two specialized cancellers, each optimized for its specific echo type. The first echo canceller provides precise acoustic echo cancellation while the second provides precise network echo cancellation, with both working together to maintain precision across different audio qualities.
Solution Approach 2:
The system dynamically switches between or combines the operations of the first and second echo cancellers based on the detected audio signal characteristics. This dynamic adaptation allows the system to maintain high cancellation precision across varying audio qualities by selecting the appropriate canceller or combination for each scenario.
Data Source
AI summary
Methods and systems for a dual echo canceller (EC) are disclosed and may include cancelling echo in utilizing a dual echo canceller, wherein said dual echo canceller includes an active echo canceller and an adaptive echo canceller. Filter coefficients may be copied from the adaptive echo canceller to the active echo canceller for the cancellation, based on whether said adaptive echo canceller has converged. The coefficients may be copied utilizing copy logic, which may comprise divergence detection and/or echo path change detection. The coefficients may be reset to default settings utilizing the copy logic. The coefficients may be calculated utilizing normalized block least mean squares (NBLMS), and may be calculated when the NBLMS is enabled by update logic. The coefficients may be calculated utilizing linear predictive coefficient (LPC) filtered uplink and downlink signals.