Signal processing apparatus and method
DCFirst Claim
1. A noninvasive physiological monitor comprising:
- a signal processor communicating with a detector responsive to light attenuated by body tissue, said detector producing a detector output waveform, said signal processor receiving said detector output waveform and configured to transform said detector output waveform into spectral data, said signal processor further configured to identify spectral peaks and frequencies corresponding to said spectral peaks from said spectral data, and configured to apply a plurality of rules to said spectral peaks and said corresponding frequencies in order to determine pulse rate estimate.
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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.
896 Citations
10 Claims
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1. A noninvasive physiological monitor comprising:
- a signal processor communicating with a detector responsive to light attenuated by body tissue, said detector producing a detector output waveform, said signal processor receiving said detector output waveform and configured to transform said detector output waveform into spectral data, said signal processor further configured to identify spectral peaks and frequencies corresponding to said spectral peaks from said spectral data, and configured to apply a plurality of rules to said spectral peaks and said corresponding frequencies in order to determine pulse rate estimate.
- View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of electronically calculating a physiological parameter in a patient comprising the steps of:
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transmitting light through tissue having flowing blood; detecting said light after it has passed through said tissue; generating an output signal indicative of the intensity of said light after attenuation; transforming the output signal into spectral data; identifying spectral peaks and frequencies corresponding the spectral peaks from the spectral data; and calculating an estimate of pulse rate by applying a plurality of rules to the spectral peaks and the corresponding frequencies. - View Dependent Claims (9, 10)
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Specification