Dual Microphone Echo Cancellation in Mobile Terminals
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Solution Overview
Problem
Existing mobile phone designs face echo issues during hands-free calls due to the close proximity of the primary microphone and speaker, which causes the voice from the other end to be picked up by the microphone and sent back as echo, degrading call quality.
Innovation Solution
The system rearranges the primary microphone on the bottom and the auxiliary microphone on the top of the mobile terminal, with the auxiliary microphone positioned far from the speaker, creating a diagonal alignment, allowing the auxiliary microphone to acquire outside sound and the primary microphone to acquire environmental noise, and using a de-noising module to filter out noise and improve echo cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the primary microphone is arranged close to the speaker for hands-free call, then the speaker volume can be high, but the voice from the speaker is picked up by the microphone causing serious echo
Solution Approach 1:
The patent divides the microphone system into two separate microphones: a primary microphone for picking up user voice and an auxiliary microphone for picking up environmental noise. This segmentation allows the primary microphone to be positioned close to the speaker for high volume hands-free calls while the auxiliary microphone handles noise cancellation, preventing echo from the speaker being picked up by the wrong microphone.
Solution Approach 2:
The auxiliary microphone acts as an intermediary element that captures environmental noise and speaker output, which is then processed by the de-noising algorithm to cancel out echo and background noise. This intermediary microphone enables the system to distinguish between user voice and unwanted sounds, resolving the echo problem while maintaining high speaker volume.
2Measurement precision
If the primary microphone is placed on the bottom for handheld call, then it can pick up user's voice well, but it is too close to the speaker for hands-free call causing echo
Solution Approach 1:
The patent makes the auxiliary microphone a multi-functional component that serves dual purposes: it picks up environmental noise during both handheld and hands-free calls, and it specifically captures speaker output during hands-free calls for echo cancellation. This universal noise-capturing function allows the primary microphone to maintain its optimal position for voice pickup while the auxiliary microphone compensates for the echo issue during hands-free operation.
3Reliability
If dual-microphone de-noising design is adopted, then environmental noise can be filtered, but the placement requirements become complex
Solution Approach 1:
The patent applies local quality by assigning specific spatial roles to each microphone: the primary microphone is optimally positioned for capturing user voice (bottom for handheld), while the auxiliary microphone is positioned to capture environmental noise and speaker output (top or side). This localized optimization of microphone positions for their specific functions simplifies the overall placement strategy while maintaining effective noise filtering capability.
Data Source
AI summary
A method and system for improving an echo in a hands-free call of a mobile terminal may include the mobile terminal comprising a speaker, a primary microphone and an auxiliary microphone; the distance from the primary microphone to the speaker can be less than that from the auxiliary microphone to the speaker; and the method may include using the auxiliary microphone to acquire outside sound during a hands-free call.