Single Transducer Full Duplex Circuit Noise Suppression
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Solution Overview
Problem
Conventional full duplex talking devices face challenges with echo cancellation and noise reduction due to changing ambient acoustic characteristics and the acoustic transfer characteristics of the human body, leading to inadequate performance in suppressing external noise and wind noise.
Innovation Solution
A single-transducer full duplex talking circuit is developed, combining an analog bridge circuit and a digital signal processing circuit with algorithms for echo cancellation, which includes a transfer function identification filter, coefficient updating algorithm, and erroneous correction detection to dynamically adjust and compensate for signal changes, effectively isolating the transducer from external noise and maintaining clear transmission signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If independent earphone and microphone are used in full duplex talking device, then the device can achieve basic full duplex function, but external noise and wind noise cannot be effectively suppressed
Solution Approach 1:
The patent combines the earphone and microphone into a single integrated unit with a shared transducer. The transducer serves dual functions as both speaker and microphone, allowing the device to achieve full duplex communication while isolating the transducer from external noise environments. This merging eliminates the need for separate independent components and provides noise isolation benefits.
2Object-generated harmful factors
If echo canceling function is implemented in conventional full duplex talking circuit, then reception signals mixed with transmission signals can be removed, but the function fails to operate adequately when ambient acoustic environment changes
Solution Approach 1:
The patent implements dynamic adaptation mechanisms that allow the echo canceling function to adjust to changing acoustic environments. The system continuously monitors and adapts to variations in ambient acoustic characteristics, ensuring effective echo cancellation regardless of environmental changes. This dynamic approach replaces static echo cancellation with adaptive processing.
Solution Approach 2:
The patent employs feedback mechanisms where the system continuously monitors the acoustic environment and adjusts its echo cancellation parameters accordingly. By using the transmitted signal and monitoring the received signal, the system dynamically updates its echo model to maintain effective cancellation under varying conditions.
3Measurement precision
If microphone sensitivity is increased to compensate for increased distance from mouth, then transmission signal can be received, but external noise and wind noise become more prominent
Solution Approach 1:
By merging the microphone and earphone into a single unit with a shared transducer, the system achieves adequate signal reception without needing to increase microphone sensitivity. The integrated design maintains the transducer in a controlled environment that naturally isolates it from external noise, eliminating the need for high-sensitivity microphones that would amplify background noise.
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 solution ensures effective echo cancellation and noise reduction, even under varying acoustic conditions, by dynamically adjusting to changes in signal strength and frequency characteristics, significantly improving the clarity of transmission signals and suppressing external noise by 90 dB or more.
Implementation Method 1
a single transducer having a receiving and transmitting function
Data Source
AI summary
A full duplex talking audio circuit uses a single transducer ZT which, even when various characteristics including the strength of a transmission signal change from moment to moment, enables the adequate operation of an echo canceling function and sufficiently compensates for the deterioration of the frequency characteristics of the transmission signal due to the acoustic transfer characteristics of the human body.