Signal processing apparatus
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 time-domain signal that is indicative of light of a first wavelength that has been attenuated by body tissue carrying arterial blood;
receiving a second time-domain signal that is indicative of light of a second wavelength that has been attenuated by the body tissue carrying arterial blood;
electronically transforming the first and second time-domain signals into respective first and second frequency-domain signals;
electronically determining a comparison value for each of a plurality of non-zero frequency components of the first and second frequency-domain signals, each comparison value comprising a comparison of the amount of a frequency component in the first frequency-domain signal versus the amount of that frequency component in the second frequency-domain signal;
electronically selecting a frequency component that exhibits physiological characteristics of arterial blood using, at least in part, the corresponding comparison value; and
electronically determining the measurement value for the characteristic of arterial blood using the selected frequency component.
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Abstract
The present disclosure describes a method and an apparatus for analyzing measured signals using various processing techniques. In certain embodiments, the measured signals are physiological signals. In certain embodiments, the measurements relate to blood constituent measurements including blood oxygen saturation.
960 Citations
16 Claims
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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:
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receiving a first time-domain signal that is indicative of light of a first wavelength that has been attenuated by body tissue carrying arterial blood; receiving a second time-domain signal that is indicative of light of a second wavelength that has been attenuated by the body tissue carrying arterial blood; electronically transforming the first and second time-domain signals into respective first and second frequency-domain signals; electronically determining a comparison value for each of a plurality of non-zero frequency components of the first and second frequency-domain signals, each comparison value comprising a comparison of the amount of a frequency component in the first frequency-domain signal versus the amount of that frequency component in the second frequency-domain signal; electronically selecting a frequency component that exhibits physiological characteristics of arterial blood using, at least in part, the corresponding comparison value; and electronically determining the measurement value for the characteristic of arterial blood using the selected frequency component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A signal processor apparatus for determining a measurement value for a characteristic of arterial blood, the signal processor apparatus comprising:
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an input port to receive a first and second time-domain signals from a light-sensitive detector, the first time-domain signal being indicative of light of a first wavelength that has been attenuated by body tissue carrying arterial blood, the second time-domain signal being indicative of light of a second wavelength that has been attenuated by the body tissue carrying arterial blood; and a processor programmed to perform a method comprising, transforming the first and second time-domain signals into respective first and second frequency-domain signals; determining a comparison value for each of a plurality of non-zero frequency components of the first and second frequency-domain signals, each comparison value comprising a comparison of the amount of a frequency component in the first frequency-domain signal versus the amount of that frequency component in the second frequency-domain signal; selecting a frequency component that exhibits physiological characteristics of arterial blood using, at least in part, the corresponding comparison value; and determining the measurement value for the characteristic of arterial blood using the selected frequency component. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification