Patent ID: 8185180
Filing Date: 2012-05-22
Classification: A61B,H04J

Abstract:
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: outputting activation signals to activate one or more light sources to cause emissions at least two different wavelengths; wherein the activation signals include at least one period of inactivation; receiving a detected composite signal indicative of an attenuation by said body tissue of said at least two different wavelengths; demodulating said composite signal into a first intensity signal responsive to said attenuation of at least a first of the at least two wavelengths, a second intensity signal responsive to said attenuation of at least a second of the at least two wavelengths and a third signal representative of a non-physiological portion of the composite signal, wherein said demodulation is based at least in part on the inactivation; and determining an indication of a physiological parameter of said body tissue based on one or more of said first and second intensity signals.