Microphone Array Calibration for Phase-Tolerant Beamforming
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Solution Overview
Problem
Conventional microphone array calibration methods fail to consider phase tolerances across microphones, leading to performance degradation in beamforming algorithms due to production tolerances among microphones in the array.
Innovation Solution
Systems and techniques for microphone array calibration that provide both phase and magnitude calibration, with local storage of calibration coefficients and central application of calibration coefficients to replace uncalibrated microphone signals, using a two-wire interface for transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microphone array calibration methods are used, then manufacturing simplicity is maintained, but beamforming performance degrades due to production tolerances among microphones
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements during the microphone manufacturing process itself, rather than after distribution. The calibration system measures and stores compensation coefficients in non-volatile memory at the factory, so that each microphone is pre-calibrated to account for production tolerances before being deployed in an array.
Solution Approach 2:
The patent uses an intermediary calibration system that includes a signal generator, reference microphone, and processing device. This intermediary system measures the frequency response of each microphone and generates compensation coefficients that mediate between the manufacturing variations and the final beamforming performance.
2Reliability
If no calibration is performed after microphones are distributed and installed, then ease of operation is maintained, but performance degradation occurs due to production tolerances
Solution Approach 1:
The calibration is performed in advance during manufacturing, storing compensation coefficients in non-volatile memory. This preliminary action ensures that when microphones are distributed and installed, no additional calibration steps are required from the user, maintaining ease of operation while improving reliability.
Solution Approach 2:
Each microphone is self-calibrated during manufacturing with its compensation coefficients stored in its own non-volatile memory. The microphone autonomously applies these coefficients during operation, eliminating the need for external calibration procedures after installation.
3Reliability
If only magnitude calibration is performed, then device complexity is reduced, but phase tolerance issues remain causing performance degradation
Solution Approach 1:
The patent changes the calibration approach from conventional magnitude-only calibration to a more comprehensive calibration that includes both magnitude and phase parameters. The calibration system measures the complex frequency response (magnitude and phase) of each microphone and generates compensation coefficients that address both aspects, improving beamforming performance.
Data Source
AI summary
Disclosed herein are systems and techniques for microphone array calibration, as well as communication systems in which calibrated microphones can be used. The systems and techniques disclosed herein may provide both phase and magnitude calibration for microphone arrays, resulting in improved performance for beamforming and other applications. Further, various systems and methods are disclosed herein for local storage of calibration coefficients in the microphone array (e.g., at the time of manufacture and calibration). Further, various systems and methods disclosed herein may include central application of the calibration of a microphone array (e.g., in an edge processor at operation time) to replace uncalibrated microphone signals with calibrated microphone signals further down in the signal chain.