Dynamic Threshold Noise Attenuation for Full-Duplex Echo Control
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Solution Overview
Problem
Full-duplex audio communication systems suffer from echo issues, which are unpleasant for users, and existing echo compensators and suppressors either fail to effectively address non-linear echo mechanisms or inadvertently attenuate useful content.
Innovation Solution
A communication terminal with a noise attenuation module that dynamically adjusts an activation threshold based on the presence or absence of received signals, treating echoes as noise when useful content is present, thereby reducing perceptible echoes without affecting the transmission of audio signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an echo suppressor is used to attenuate transmitted signals when signals are simultaneously received, then echo attenuation is improved, but useful content in transmitted signals is also attenuated
Solution Approach 1:
The invention dynamically changes the activation threshold parameter based on signal conditions. When useful content is detected in the transmitted signal, the activation threshold is adjusted to prevent attenuation of the useful content while still attenuating echoes. This parameter adaptation resolves the contradiction by making the suppression selective rather than blanket.
Solution Approach 2:
The invention introduces dynamic control of the noise attenuation module based on real-time analysis of transmitted and received signals. The module transitions between active and inactive states, and adjusts activation thresholds dynamically, allowing it to suppress echoes only when appropriate while preserving useful content. This dynamic behavior resolves the static contradiction between suppression and preservation.
2Object-affected harmful factors
If a linear echo compensator is used to subtract received signal contributions from transmitted signals, then echo compensation is improved when echo is proportional to received signals, but effectiveness deteriorates when non-linear behaviors such as saturation occur
Solution Approach 1:
The invention segments the echo handling into two distinct approaches: a linear echo compensator for proportional echo components and a noise attenuation module for non-linear echo components. This segmentation allows each module to specialize in its appropriate domain, with the compensator handling linear cases and the attenuation module handling non-linear cases, thereby resolving the limitation of linear compensators alone.
Solution Approach 2:
The noise attenuation module acts as an intermediary that processes transmitted signals after linear compensation has been applied. It provides an additional layer of echo handling that specifically addresses non-linear behaviors that the linear compensator cannot handle, complementing rather than replacing the linear compensation approach.
3Device complexity
If the noise attenuation module uses a fixed activation threshold, then implementation is simplified, but ability to distinguish between noise and useful low-amplitude signals deteriorates
Solution Approach 1:
The invention changes the activation threshold parameter dynamically based on the detected presence of useful content in the transmitted signal. When useful content is present, the threshold is adjusted to allow low-amplitude useful signals to pass through. When no useful content is present, the threshold enables noise suppression. This parameter adaptation resolves the contradiction between simplicity and precision.
Data Source
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AI summary
A full duplex audio communication terminal (100) comprises a noise attenuation module (4) arranged on a transmission path of the terminal. The noise attenuation module comprises two activation thresholds, which are respectively intended to be adjusted above a noise level and above an echo level of transmission signals (TC) produced by the terminal. The first or the second activation threshold is selected as a function of the detection of signals (R) received by said terminal. An improvement to the suppression in the transmission signals of echoes from received signals is thus obtained which is compatible with the principle of full duplex communication. Preferably, the noise attenuation module processes transmission signals which are produced by an echo compensator (2). Residual echo still present in the transmission signals already processed by the echo compensator is thus further reduced.