Signal processing apparatus and method
DCFirst Claim
1. A physiological monitor adapted to be attached to a living being having a heart beating at an unknown pulserate, said monitor comprising:
- a detector responsive to physiological properties relating to heartbeats, said detector producing a detector output waveform; and
a signal processor operatively coupled to said detector, said signal processor receiving said detector output waveform, said signal processor configured to;
transform said detector output waveform into a spectral domain waveform;
identify a series of spectral peaks and peak frequencies corresponding to said spectral peaks in said spectral domain waveform; and
apply a plurality of rules to said spectral peaks and said peak frequencies in order to determine an estimate for said pulserate.
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Abstract
A method and an apparatus to analyze two measured signals that are modeled as containing desired and undesired portions such as noise, FM and AM modulation. Coefficients relate the two signals according to a model defined in accordance with the present invention. In one embodiment, a transformation is used to evaluate a ratio of the two measured signals in order to find appropriate coefficients. The measured signals are then fed into a signal scrubber which uses the coefficients to remove the unwanted portions. The signal scrubbing is performed in either the time domain or in the frequency domain. The method and apparatus are particularly advantageous to blood oximetry and pulserate measurements. In another embodiment, an estimate of the pulserate is obtained by applying a set of rules to a spectral transform of the scrubbed signal. In another embodiment, an estimate of the pulserate is obtained by transforming the scrubbed signal from a first spectral domain into a second spectral domain. The pulserate is found by identifying the largest spectral peak in the second spectral domain.
1448 Citations
16 Claims
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1. A physiological monitor adapted to be attached to a living being having a heart beating at an unknown pulserate, said monitor comprising:
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a detector responsive to physiological properties relating to heartbeats, said detector producing a detector output waveform; and a signal processor operatively coupled to said detector, said signal processor receiving said detector output waveform, said signal processor configured to; transform said detector output waveform into a spectral domain waveform; identify a series of spectral peaks and peak frequencies corresponding to said spectral peaks in said spectral domain waveform; and apply a plurality of rules to said spectral peaks and said peak frequencies in order to determine an estimate for said pulserate. - View Dependent Claims (2)
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3. In a physiological monitor attached to a living organism, said organism having a heart beating at an unknown pulserate, said monitor having a detector responsive to physiological properties relating to heartbeats, said detector producing a detector output waveform, a method comprising the steps of:
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transforming said detector output waveform into a spectral domain waveform; identifying a series of spectral peaks and peak frequencies corresponding to said spectral peaks in said spectral domain waveform; and applying a plurality of rules to said spectral peaks and said peak frequencies in order to determine an estimate for said pulserate.
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4. A physiological monitor adapted to be attached to a living organism, said organism having a heart beating at an unknown pulserate, said monitor comprising:
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a detector responsive to physiological properties relating to said heartbeats, said detector producing a detector output waveform; and a signal processor operatively coupled to said detector, said signal processor receiving said detector output waveform, said signal processor configured to; perform a first transform to transform said detector output waveform into a waveform in a first transform domain; perform a second transform, to transform said waveform in said first transform domain into a waveform in a second transform domain; search said waveform in said second transform domain for a largest spectral peak and a first frequency corresponding to said largest spectral peak; and compute an estimate of said unknown pulserate from said first frequency. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a physiological monitor attached to a living organism, said organism having a heart beating at an unknown pulserate, said monitor having a detector responsive to physiological properties relating to said heartbeats, said detector producing a detector output waveform, a method comprising the steps of:
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performing a first transform to transform said detector output waveform into a waveform in a first transform domain; performing a second transform, to transform said waveform in said first transform domain into a waveform in a second transform domain; searching said waveform in said second transform domain for a largest spectral peak and a first frequency corresponding to said largest spectral peak; and computing an estimate of said unknown pulserate from said first frequency.
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Specification