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Signal processing apparatus and method

  • US 8,190,227 B2
  • Filed: 02/09/2009
  • Issued: 05/29/2012
  • Est. Priority Date: 04/14/1997
  • Status: Expired due to Fees
First Claim
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1. In a signal processor, a method of determining a measurement value for a characteristic of arterial blood, the method comprising:

  • receiving a first signal from a light-sensitive detector, the first signal being indicative of light of a first wavelength that has been attenuated over a period of time by body tissue carrying arterial blood;

    receiving a second signal from the light-sensitive detector, the second signal being indicative of light of a second wavelength that has been attenuated over the period of time by the body tissue carrying arterial blood;

    electronically identifying peak frequency components of the first and second signals;

    electronically determining a slope value corresponding to each of one or more of the peak frequency components, each slope value comprising a comparison of the respective amounts of the corresponding peak frequency component in the first and second signals;

    electronically selecting a peak frequency component that exhibits physiological characteristics of arterial blood using, at least in part, the corresponding slope value; and

    electronically determining the measurement value for the characteristic of arterial blood using the selected peak frequency.

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