Microphone Array Calibration Using Phase Difference Data
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Solution Overview
Problem
Current microphone array beamforming methods require either costly microphone matching or offline calibration, which are time-consuming and increase production costs, especially for small separation microphones.
Innovation Solution
A real-time calibration method using a pair of microphones that generates phase difference data to correct phase and amplitude mismatches, allowing for accurate beamforming without the need for pre-matching or offline calibration, implemented through a calibrator and phase/amplitude correction system that processes signals in the frequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microphone matching is performed during manufacturing, then beamforming accuracy is improved, but production time increases and yield decreases
Solution Approach 1:
The patent applies preliminary action by performing microphone calibration in advance during the manufacturing process. A calibration signal is played through a speaker before the microphones are assembled into the final product, allowing calibration data to be stored in non-volatile memory. This enables the microphones to be pre-calibrated individually, improving beamforming accuracy while maintaining production efficiency through automated calibration procedures.
Solution Approach 2:
The patent uses an intermediary calibration signal as a mediator between the manufacturing process and the final beamforming application. The calibration signal serves as an intermediate step that captures microphone characteristics and stores them for later use, enabling accurate beamforming without requiring time-consuming manual matching during final assembly.
2Measurement precision
If offline microphone calibration is performed, then beamforming accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent implements self-service by enabling the microphone calibration system to automatically perform calibration without requiring external specialized equipment or manual intervention. The system uses built-in speakers and microphones to generate and measure calibration signals, storing the results in non-volatile memory. This automated self-calibration approach reduces manufacturing costs while maintaining high beamforming accuracy.
Solution Approach 2:
The patent applies parameter changes by transforming the calibration process from a manual, equipment-intensive offline procedure to an automated process that uses electrical signal parameters. Calibration signals are generated electrically and measured through the existing microphone circuitry, with results stored as digital parameters in memory, simplifying the manufacturing process and reducing costs.
3Ease of manufacture
If real-time calibration is implemented, then production cost is reduced, but system complexity increases
Solution Approach 1:
The patent applies universality by designing a calibration system that performs multiple functions using the same hardware components. The built-in speaker and microphone serve both as operational components and as calibration tools. The same signal processing circuitry is used for both normal audio processing and calibration measurements, reducing the need for additional specialized components and minimizing system complexity.
Solution Approach 2:
The patent uses copying by creating a digital replica of the microphone's acoustic characteristics during calibration. The calibration process captures the microphone's frequency response and other parameters, storing them as digital data in non-volatile memory. This digital copy is then used during beamforming operations to compensate for microphone variations, eliminating the need for physical microphone matching while keeping the system simple.
Data Source
AI summary
An apparatus for providing real-time calibration for two or more microphones. A calibrator for receiving a left microphone signal and a right microphone signal and generating phase difference data. A phase and amplitude correction system for receiving one of the left microphone signal or the right microphone signal the phase difference data and generating calibration data for a beamformer. The beamformer receiving the calibration data, the left microphone signal and the right microphone signal and generating a monaural beamformed signal.