Phase Correcting System for Microphone Arrays
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Solution Overview
Problem
Production variances in microphone sensors lead to inconsistent phase responses at low frequencies, making it challenging to achieve precise beamforming requirements, as the phase difference between microphones can vary significantly, necessitating careful handling and pairing to maintain accurate phase characteristics.
Innovation Solution
A phase correcting system comprising input and output terminals connected to a transducer, with a feedback element that includes a low pass filter with a variable cut-off frequency, allowing for the adaptation of the phase response by feeding a low pass filtered signal back to the transducer, effectively acting as a high-pass filter to correct the phase output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If selection or sorting is used to guarantee phase difference between microphones, then phase consistency is improved, but device complexity and handling requirements increase
Solution Approach 1:
The patent replaces the mechanical system of physical selection and sorting with an electrical system. A feedback circuit with adjustable low-pass filter is connected to each microphone's output terminal, allowing phase correction through electrical signal processing rather than physical reassignment. This substitutes manual/mechanical matching operations with automated electrical adjustment.
Solution Approach 2:
The patent changes the electrical parameters of the microphone system by introducing adjustable cut-off frequencies in the feedback circuits. By varying the cut-off frequency parameter, the phase response of each microphone can be individually adjusted to achieve consistency, replacing the need for fixed physical matching based on manufacturing characteristics.
2Manufacturing precision
If physical matching of transducers is performed, then phase characteristics are improved, but productivity decreases
Solution Approach 1:
The patent enables each microphone to self-adjust its phase characteristics through the feedback circuit. By adjusting the cut-off frequency parameter in each feedback loop, the microphones automatically compensate for their individual manufacturing variations, eliminating the need for external matching operations and improving assembly productivity.
3Manufacturing precision
If careful handling is used to maintain correct sequence, then phase consistency is improved, but ease of operation worsens
Solution Approach 1:
The patent replaces the mechanical requirement for careful physical handling and sequence maintenance with an electrical adjustment mechanism. The feedback circuits with adjustable cut-off frequencies allow phase correction without requiring operators to maintain specific physical arrangements or sequences, significantly improving ease of operation.
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
This solution enables precise control of the phase response, allowing for the reduction of phase differences between microphones to within acceptable limits, eliminating the need for physical matching of transducers and ensuring consistent phase characteristics across multiple sensors.
Implementation Method 1
a circuit configured to receive a first signal from the feedback entry conductor and output, on the feedback exit conductor, a second signal as a low pass filtered first signal, the circuit having a variable cut-off frequency of the low pass filtering
Data Source
AI summary
A phase correcting system for connection with a transducer. The phase correction may take place before amplifying the output of the transducer. The phase correction system comprises a circuit configured to low-pass filter an input and feed the output to the non-signal terminal of the transducer. This circuit may comprise a transconductance amplifier.