Method and apparatus for demodulating signals in a pulse oximetry system
First Claim
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1. A method of determining an indication of a physiological parameter by demodulating a composite output signal from a detector of a noninvasive optical sensor, the method comprising:
- activating at least one light source to cause a first emission at a first wavelength;
activating the at least one light source to cause a second emission at a second wavelength at least once before a reactivation of the at least one light source;
detecting the composite output signal indicative of an attenuation by said body tissue of said first and second emissions;
selectively demodulating only certain harmonics of desired components of the detected composite signal into a first intensity signal responsive to said attenuation of said first emission and a second intensity signal responsive to said attenuation of said second emission; and
determining an indication of a physiological parameter of said body tissue based on one or more of said first and second intensity signals.
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Abstract
A method and an apparatus measure blood oxygenation in a subject. A light source is activated to cause a first emission at a first wavelength and a second emission at a second wavelength. A detector detects a composite signal indicative of an attenuation of the first and second wavelengths by tissue of a patient. The composite signal is demodulated into a first intensity signal and a second intensity signal. Blood oxygenation in the subject is determined from the first and second intensity signals.
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8 Claims
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1. A method of determining an indication of a physiological parameter by demodulating a composite output signal from a detector of a noninvasive optical sensor, the method comprising:
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activating at least one light source to cause a first emission at a first wavelength; activating the at least one light source to cause a second emission at a second wavelength at least once before a reactivation of the at least one light source; detecting the composite output signal indicative of an attenuation by said body tissue of said first and second emissions; selectively demodulating only certain harmonics of desired components of the detected composite signal into a first intensity signal responsive to said attenuation of said first emission and a second intensity signal responsive to said attenuation of said second emission; and determining an indication of a physiological parameter of said body tissue based on one or more of said first and second intensity signals. - View Dependent Claims (2, 3, 4)
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5. A system for determining an indication of a physiological parameter by demodulating a composite output signal from a detector of a noninvasive oximetry optical sensor, the system comprising:
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an input configured to receive a composite signal indicative of an attenuation by body tissue of a first and second emission; and a processor configured to selectively demodulate only certain harmonics of desired components of said composite signal into a first intensity signal responsive to said attenuation of said first emission and into a second intensity signal responsive to said attenuation of said second emission;
wherein said processor is further configured to determine an indication of a physiological parameter of said body tissue based on one or more of said first and second intensity signals. - View Dependent Claims (6, 7, 8)
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Specification