Method and system for limiting interference in electroencephalographic signals
First Claim
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1. A method for processing a physiological signal of interest also comprising unwanted spurious signals, the method comprising:
- limiting at least one narrow-band spurious signal by performing one or more windowed Fourier transforms on one or more segments of said physiological signal, and filtering Fourier coefficients having temporal variation substantially less than the temporal variation of said physiological signal and having relative temporal duration substantially greater than relative frequency bandwidth, a relative temporal duration being a temporal duration in comparison to the temporal duration of the signal segment being processed, and a relative frequency bandwidth being a bandwidth in comparison to the bandwidth of the signal segment being processed; and
limiting at least one intermittently-occurring spurious signal by performing one or more wavelet transforms on one or more segments of said physiological signal, and filtering wavelet coefficients having characteristics that are distinguishable from said physiological signal of interest and having relative temporal duration substantially less than relative frequency bandwidth.
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Abstract
This invention provides methods and systems for removing or limiting interference and artifacts often found in EEG signals and/or EOG signals and/or other physiological signals, and produces output signals that can be of greater use for analytic or diagnostic purposes, such as sleep studies. Interference and artifacts are removed by applying a plurality of filtering methods targeted to the particular time-frequency characteristics of the anticipated interference.
131 Citations
32 Claims
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1. A method for processing a physiological signal of interest also comprising unwanted spurious signals, the method comprising:
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limiting at least one narrow-band spurious signal by performing one or more windowed Fourier transforms on one or more segments of said physiological signal, and filtering Fourier coefficients having temporal variation substantially less than the temporal variation of said physiological signal and having relative temporal duration substantially greater than relative frequency bandwidth, a relative temporal duration being a temporal duration in comparison to the temporal duration of the signal segment being processed, and a relative frequency bandwidth being a bandwidth in comparison to the bandwidth of the signal segment being processed; and
limiting at least one intermittently-occurring spurious signal by performing one or more wavelet transforms on one or more segments of said physiological signal, and filtering wavelet coefficients having characteristics that are distinguishable from said physiological signal of interest and having relative temporal duration substantially less than relative frequency bandwidth. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for processing a physiological signal of interest also comprising unwanted spurious signals, the method comprising:
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applying to one or more segments of said physiological signal one or more filters for filtering signal components present in sub-domains of the time/frequency domain plane having a plurality of different shapes, wherein at least one sub-domain has a shape with a relative temporal duration substantially greater than a relative frequency bandwidth, a relative temporal duration of a shape being a temporal duration of the shape in comparison to the temporal duration of the signal segment being processed, and a relative frequency bandwidth of a shape being a bandwidth of the shape in comparison to the bandwidth of the signal segment being processed, and wherein at least one sub-domain has a shape with a relative temporal duration substantially less than a relative frequency bandwidth;
- View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A computer system for processing a physiological signal of interest also comprising unwanted spurious signals, the system comprising a computer readable memory comprising encoded instructions for causing a processor to perform the steps of
limiting at least one narrow-band spurious signal by performing one or more windowed Fourier transforms on one or more segments of said physiological signal, and filtering Fourier coefficients having temporal variation substantially less than the temporal variation of said physiological signal and having relative temporal duration substantially greater than relative frequency bandwidth, a relative temporal duration being a temporal duration in comparison to the temporal duration of the signal segment being processed, and a relative frequency bandwidth being a bandwidth in comparison to the bandwidth of the signal segment being processed; - and
limiting at least one intermittently-occurring spurious signal by performing one or more wavelet transforms on one or more segments of said physiological signal, and filtering wavelet coefficients having characteristics that are distinguishable from said physiological signal of interest and having relative temporal duration substantially less than relative frequency bandwidth.
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32. A computer readable memory for processing a physiological signal of interest also comprising unwanted spurious signals, the memory comprising encoded instructions for causing a processor to perform the steps of
limiting at least one narrow-band spurious signal by performing one or more windowed Fourier transforms on one or more segments of said physiological signal, and filtering Fourier coefficients having temporal variation substantially less than the temporal variation of said physiological signal and having relative temporal duration substantially greater than relative frequency bandwidth, a relative temporal duration being a temporal duration in comparison to the temporal duration of the signal segment being processed, and a relative frequency bandwidth being a bandwidth in comparison to the bandwidth of the signal segment being processed; - and
limiting at least one intermittently-occurring spurious signal by performing one or more wavelet transforms on one or more segments of said physiological signal, and filtering wavelet coefficients having characteristics that are distinguishable from said physiological signal of interest and having relative temporal duration substantially less than relative frequency bandwidth.
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Specification