Three-Wire Headset Crosstalk Mitigation via Noise Injection
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Solution Overview
Problem
Wireless mobile devices with three-wire headsets often experience crosstalk due to shared electrical paths, leading to frustrating communication issues, and existing solutions like differential amplifiers are ineffective due to unknown resistances, while upgrading to four-wire circuits is costly and not universally applicable.
Innovation Solution
A system that includes an evaluation component to measure noise voltage at a common point, an aggregation component to add a noise voltage to the microphone power supply, and an optimization component, such as a differential amplifier or analog-to-digital converters, to selectively remove noise from the microphone output, mitigating crosstalk by creating a known fraction of noise signal at all relevant points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a three-wire headset is used to reduce device cost and complexity, then device cost and complexity are reduced, but crosstalk occurs between microphone and speaker
Solution Approach 1:
The patent introduces an intermediary noise cancellation circuit between the common path and the microphone signal path. This circuit measures the noise voltage on the common path and subtracts it from the microphone signal, effectively mediating the harmful interaction between speaker and microphone while maintaining the three-wire configuration.
Solution Approach 2:
The patent extracts the noise component from the combined microphone-speaker signal by measuring it separately on the common path. The noise voltage is identified and removed through subtraction, separating the harmful crosstalk from the useful microphone signal.
2Object-generated harmful factors
If differential amplifiers are used to cancel noise, then crosstalk mitigation is attempted, but the solution is ineffective due to unknown resistances in the common path
Solution Approach 1:
The patent replaces the traditional differential amplifier approach with an analog-to-digital converter-based system. Instead of relying on analog subtraction that is sensitive to resistance variations, the system converts signals to digital form where precise noise cancellation can be achieved through digital signal processing, eliminating the dependency on unknown resistance values.
3Object-generated harmful factors
If four-wire circuits are implemented to eliminate crosstalk, then crosstalk is eliminated, but device cost increases
Solution Approach 1:
The patent creates a copy of the noise signal present on the common path by measuring it with a high-input-impedance amplifier. This noise copy is then subtracted from the microphone signal, achieving four-wire level noise cancellation while maintaining the physical three-wire connection, thus avoiding the cost and complexity of actual four-wire implementation.
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
Effectively reduces crosstalk in three-wire headsets by ensuring a consistent noise signal is present across all points, allowing for accurate cancellation and improving audio quality without increasing device costs or complexity.
Implementation Method 1
an evaluation component to measure noise voltage at a common point
Implementation Method 2
an aggregation component to add a noise voltage to the microphone power supply
Implementation Method 3
An optimization component is also included that selectively removes a noise voltage from a microphone output voltage. In some embodiments, the optimization component can be a differential amplifier or two analog-to-digital converters.
Data Source
AI summary
Audible crosstalk can be mitigated in a low-cost three-wire device having audio capability and/or voice applications. In some embodiments, a voltage can be introduced in a microphone power supply that is approximately the same as a measured noise voltage and the resulting voltage appearing at a microphone output can be optimized to mitigate the noise voltage and, thus, the presence of crosstalk. In some embodiments, a microphone within a circuit can be isolated to mitigate crosstalk by introducing current into a circuit that is approximately the same as a measured current, but having a flow in an opposite direction.