Acoustic Echo Cancellation for Wireless Microphone Systems
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Solution Overview
Problem
Existing acoustic echo cancellation systems fail to effectively cancel echoes in wireless microphone and speaker systems due to non-linear compression techniques used in wireless transmission, which alter the audio signal and prevent accurate comparison between the original and received signals.
Innovation Solution
A system with a base unit that includes a compression module for compressing audio signals, a decompression module to decompress signals received over a wireless link, and an acoustic echo canceller that applies a linear transformation to cancel detected echo components, ensuring effective echo cancellation by replicating the decompression process and monitoring signal gradients for transmission errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-linear compression techniques are used for wireless transmission, then transmission efficiency is improved, but signal fidelity deteriorates
Solution Approach 1:
The patent creates a local copy of the compressed signal processing pipeline by implementing an identical decompression algorithm in the echo canceller. This copy exactly replicates what the remote speaker does with the transmitted signal, allowing the echo canceller to work with an accurate reference signal that matches the actual acoustic path input.
Solution Approach 2:
The echo reference signal is prepared in advance by decompressing the transmitted signal locally before it is actually transmitted over the acoustic channel. This preliminary decomposition allows the system to have the exact reference signal ready for echo cancellation, accounting for the non-linear compression effects that will be applied to the actual audio path.
2Quantity of substance
If compression is applied to reduce signal size, then bandwidth usage is improved, but echo cancellation accuracy deteriorates
Solution Approach 1:
The system creates a local copy of the compressed signal processing pipeline by implementing an identical decompression algorithm in the echo canceller. This copy exactly replicates what the remote speaker does with the transmitted signal, allowing the echo canceller to work with an accurate reference signal that matches the actual acoustic path input.
Solution Approach 2:
The patent changes the state of the reference signal by applying the same non-linear decompression transformation that is applied to the transmitted signal. This transformation converts the compressed digital signal into the actual acoustic signal that will be played through the speaker, ensuring the reference signal matches the acoustic path input despite the compression applied to reduce signal size.
3Device complexity
If standard echo cancellation methods are used, then system simplicity is maintained, but effectiveness deteriorates in wireless compressed audio systems
Solution Approach 1:
The patent creates a local copy of the compressed signal processing pipeline by implementing an identical decompression algorithm in the echo canceller. This copy exactly replicates what the remote speaker does with the transmitted signal, allowing the echo canceller to work with an accurate reference signal that matches the actual acoustic path input.
Solution Approach 2:
The patent introduces an intermediary decompression step in the signal path between the transmitted compressed signal and the echo reference signal. This intermediary process ensures that the reference signal passed to the echo canceller is in the same form as the actual acoustic signal, bridging the gap caused by non-linear compression.
Data Source
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AI summary
Systems and methods for acoustic echo cancellation with wireless microphone and speaker systems are described herein. In one embodiment, an acoustic echo canceller is provided that can, among other things, cancel an acoustic echo component of an audio signal that is produced when an audio signal transmitted to a remote speaker on a lossy wireless link is picked up by a remote microphone and transmitted back to a base station on a lossy wireless link.