Signal processing apparatus and method
First Claim
1. In a signal processor for processing at least two measured signals M1 and M2, where said signal M1 comprises a physiological signal portion S1 and may comprise a noise portion N1, and where said signal M2 comprises a physiological signal portion S2 and may comprise a noise portion N2, a method comprising:
- determining a value for a coefficient c used in a combination of M1 and M2 such that the combination of M1 and M2 approximates S1, wherein determining the coefficient c comprises comparing frequency domain representations of the two measured signals M1 and M2;
using said coefficient c to remove at least some of the noise portion N1from the measured signal M1, thereby producing an approximation A1 to said physiological signal S1; and
determining a measured output value for one or more physiological parameters based at least in part on said approximation A1.
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Accused Products
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.
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Citations
14 Claims
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1. In a signal processor for processing at least two measured signals M1 and M2, where said signal M1 comprises a physiological signal portion S1 and may comprise a noise portion N1, and where said signal M2 comprises a physiological signal portion S2 and may comprise a noise portion N2, a method comprising:
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determining a value for a coefficient c used in a combination of M1 and M2 such that the combination of M1 and M2 approximates S1, wherein determining the coefficient c comprises comparing frequency domain representations of the two measured signals M1 and M2; using said coefficient c to remove at least some of the noise portion N1from the measured signal M1, thereby producing an approximation A1 to said physiological signal S1; and determining a measured output value for one or more physiological parameters based at least in part on said approximation A1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification