Method and apparatus for demodulating signals in a pulse oximetry system
First Claim
1. A method of demodulating a detected light signal representative of light attenuated by tissue of a patient, the method comprising:
- receiving a composite signal representative of an attenuation of a first and second emissions by body tissue;
adaptively demodulating said composite signal into at least a first intensity signal representative of said attenuation of said first emission by body tissue and a second intensity signal representative of said attenuation of said second emission by body tissue;
anddetermining a physiological measurement based on the first and second intensity signals.
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Accused Products
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. In one embodiment, demodulation is based at least in part on a period when at least one of the wavelengths is not activated. In one embodiment, a modulation of the first and second wavelengths is determined in order to avoid frequencies of ambient noise. In one embodiment, the composite signal'"'"'s sampling rate is reduced before and/or after demodulation.
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Citations
20 Claims
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1. A method of demodulating a detected light signal representative of light attenuated by tissue of a patient, the method comprising:
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receiving a composite signal representative of an attenuation of a first and second emissions by body tissue; adaptively demodulating said composite signal into at least a first intensity signal representative of said attenuation of said first emission by body tissue and a second intensity signal representative of said attenuation of said second emission by body tissue; and determining a physiological measurement based on the first and second intensity signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for demodulating a detected light signal representative of light attenuated by tissue of a patient, the system comprising:
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an input for receiving a composite signal representative of an attenuation of a first and second emissions by body tissue; a demodulation module configured to adaptively demodulate said composite signal into at least a first intensity signal representative of said attenuation of said first emission by body tissue and a second intensity signal representative of said attenuation of said second emission by body tissue; and a processor configured to determine and output a physiological measurement based on the first and second intensity signals. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification