Noise reduction system and method
First Claim
Patent Images
1. A noise reduction system, comprising:
- an input unit including a linear detector array for detecting analog signals at a plurality of time snaps, thereby constructing analog signals in time domain;
a first converter coupled with the input unit, the first converter receiving the analog signals in time domain and transforming the analog signals in time domain into digital signals in time domain; and
a signal processor coupled with the first converter for receiving the digital signals in time domain, the signal processor further comprising;
a transformation unit for converting the digital signals in time domain into digital signals in frequency domain; and
noise suppressing unit configured to suppress noise in the digital signals in frequency domain by multiplying a weighting vector to the digital signals in frequency domain to obtain noise reduced digital signals in frequency domain.
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Abstract
A noise reduction system and a noise reduction method are provided. The noise reduction method estimates directions of arrival of signals by directly using a signal subspace of the signals. Noise of the signals is suppressed at directions other than the directions of arrival. In one embodiment, the signals include audio signals. The signals may be multiple wide-band signals and/or coherent signals in multipath environment with a low signal-to-noise ratio.
98 Citations
33 Claims
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1. A noise reduction system, comprising:
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an input unit including a linear detector array for detecting analog signals at a plurality of time snaps, thereby constructing analog signals in time domain; a first converter coupled with the input unit, the first converter receiving the analog signals in time domain and transforming the analog signals in time domain into digital signals in time domain; and a signal processor coupled with the first converter for receiving the digital signals in time domain, the signal processor further comprising; a transformation unit for converting the digital signals in time domain into digital signals in frequency domain; and noise suppressing unit configured to suppress noise in the digital signals in frequency domain by multiplying a weighting vector to the digital signals in frequency domain to obtain noise reduced digital signals in frequency domain. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A signal processor, comprising:
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a transformation unit configured to receive digital signals in time domain, the digital signals corresponding to a plurality of analog signals detected by a linear detector array, and to convert the digital signals in time domain into digital signals in frequency domain; and a noise suppression unit configured to receive the digital signals in frequency domain and suppress noise in the digital signals in frequency domain to obtain noise reduced digital signals in frequency domain, the noise reduced digital signals being obtained by multiplying a weighting vector with the digital signals in frequency domain. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A method for reducing noise in audio signals detected by a linear microphone array, comprising:
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preparing a plurality of snapshot vectors of the audio signals; constructing a covariance matrix from the snapshot vectors, and constructing a spectral density matrix from the covariance matrix; eigendecomposing the spectral density matrix to obtain a plurality of eigenvectors and a plurality of eigenvalues, thereby obtaining a signal subspace and a noise subspace; estimating directions of arrival of the audio signals by a spatial spectrum derived from directly using the signal subspace; preparing a weighting vector based on the directions of arrival; obtaining noise reduced audio signals using the weighting vector; and outputting the noise reduced audio signals. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification