Wave Source Direction Estimation Using Envelope Functions
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Solution Overview
Problem
Existing techniques fail to accurately estimate the direction of a wave source in environments with high surrounding noise levels.
Innovation Solution
A wave source direction estimation apparatus and method that includes input signal acquisition, cross-correlation function calculation, envelope function extraction, combined envelope function calculation, and estimated direction information generation, using a combination of microphones and signal processing techniques like Hilbert transform to enhance accuracy in noisy conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If cross-correlation function summation is used for sound source direction estimation, then the method is simple and computationally efficient, but the estimation accuracy deteriorates in high noise environments
Solution Approach 1:
The patent segments the cross-correlation function into multiple frequency bands and processes each band separately to extract envelope functions. This segmentation allows the system to focus on specific frequency components that are less affected by noise, thereby improving direction estimation accuracy while maintaining computational efficiency through targeted processing.
Solution Approach 2:
The patent introduces envelope functions as an intermediary representation between the raw cross-correlation functions and the final direction estimation. By extracting envelope functions that represent the amplitude modulation characteristics, the system creates a noise-resistant intermediate representation that preserves directional information while filtering out high-frequency noise components.
2Power
If traditional cross-correlation summation is applied, then computational load is low, but reliability of direction estimation decreases in noisy conditions
Solution Approach 1:
The patent performs preliminary processing by extracting envelope functions from cross-correlation functions in different frequency bands before performing the final summation and peak detection. This preliminary action of envelope extraction prepares the data in advance to be more resistant to noise, ensuring that the subsequent computational steps operate on pre-processed, noise-filtered representations.
Solution Approach 2:
The patent transforms the problem from direct time-domain cross-correlation summation to a multi-dimensional approach by introducing frequency band decomposition and envelope function extraction. This dimensional transformation adds frequency and envelope amplitude dimensions, allowing the system to estimate direction from multiple representation layers that are collectively more robust to noise.
Data Source
AI summary
This wave source direction estimation apparatus is capable of highly accurately estimating the direction of a wave source even in an environment with a high surrounding noise level, and is provided with: a plurality of input signal acquisition means for acquiring signals generated at a wave source as input signals; a correlation function calculation means for calculating correlation functions on the basis of the input signals acquired by the input signal acquisition means; an envelope function extraction means for extracting envelope functions on the basis of the calculated correlation functions; a combined envelope function calculation means for calculating a combined envelope function by combining the extracted envelope functions; and an estimated direction information generation means for generating estimated direction information about the wave source on the basis of the calculated combined envelope function.