Array Microphone Phase Calibration via Subband Delay Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional phase calibration modules for array microphones fail to accurately compensate for circuit-induced delays, leading to signal distortion and reduced precision in beamforming due to treating low-frequency and high-frequency components equally, resulting in suboptimal noise and interference attenuation.
Innovation Solution
A phase calibration module comprising a subband filter to extract high and low-frequency components, a delay calculation module to calculate delays between low-frequency signals, and a delay compensation filter to calibrate phase mismatches, ensuring precise compensation and improved beamforming performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional phase calibration module directly determines delays from microphone output signals, then the calibration process is simple, but the delay calculation is inaccurate due to treating low-frequency and high-frequency components equally
Solution Approach 1:
The patent segments the microphone signals into high-frequency and low-frequency components using a subband filter. The low-frequency components are specifically selected for delay calculation because they contain the circuit delay information, while high-frequency components are used for beamforming. This segmentation resolves the contradiction by focusing calibration on the relevant frequency band without requiring complete signal processing.
Solution Approach 2:
The patent applies different processing quality to different frequency components. The low-frequency components receive specialized delay calculation treatment, while high-frequency components undergo standard beamforming processing. This local quality approach improves delay calculation accuracy by concentrating computational resources on the frequency band where circuit delays are most prominent.
2Manufacturing precision
If phase calibration compensates for all frequency components equally, then the calibration process is uniform, but the beamforming precision is degraded due to signal distortion in low-frequency components
Solution Approach 1:
The patent segments the signal processing into two distinct paths: one for low-frequency components that undergo delay calculation and compensation, and another for high-frequency components that undergo beamforming. This segmentation allows each component to be processed according to its specific requirements, improving beamforming precision while managing processing complexity.
Solution Approach 2:
The patent extracts the low-frequency components from the microphone signals specifically for delay calculation. By taking out only the necessary frequency band for calibration purposes, the system achieves precise compensation without subjecting the entire signal spectrum to complex processing, thus maintaining beamforming precision.
3Measurement precision
If circuit differences among microphones are not compensated, then the system remains simple, but the phase differences include unwanted delays that degrade beamforming precision
Solution Approach 1:
The patent implements self-service calibration where the system uses its own microphone signals to calculate and compensate for circuit delays. The low-frequency components of the microphone outputs are used to determine delays, which are then applied to correct the phase differences. This self-service approach improves phase difference accuracy without requiring external calibration equipment or complex additional hardware.
Solution Approach 2:
The patent changes the frequency parameter of the signals used for delay calculation by selecting low-frequency components. This parameter change allows the system to isolate and measure circuit delays that are most prominent in the low-frequency range, thereby improving phase difference accuracy with a relatively simple calibration mechanism.
Data Source
AI summary
The invention provides a phase calibration module, calibrating phase mismatch between microphone signals output by a plurality of microphones of an array microphone. In one embodiment, the phase calibration module comprises a subband filter, a delay calculation module, and a delay compensation filter. The subband filter extracts a high frequency component and a low frequency component from each of the microphone signals to obtain a plurality of high-frequency component signals and a plurality of low-frequency component signals. The delay calculation module calculates delays between the low-frequency component signals. The delay compensation filter then compensates the low-frequency component signals for phase mismatches therebetween according to the calculated delays to obtain a plurality of calibrated low-frequency component signals.