Patent ID: 8447374

Claim:
A physiological monitor that computes arterial oxygen saturation in tissue material, the physiological monitor comprising, a light emitter which emits light of at least first and second wavelengths; a light detector responsive to light from said light emitter attenuated by body tissue, said light detector providing an output signal indicative of at least first and second intensity signals associated with said at least first and second wavelengths; and a signal processor responsive to the first and second intensity signals to encode said first intensity signal into a first complex signal in a complex time domain and to encode said second intensity signal into a second complex signal in the complex time domain, to determine ratios of said first complex signal to said second complex signal, to preferentially weigh said ratios based on a measure of confidence, to phase filter said weighted ratios to reduce an effect of noise, to calculate arterial oxygen saturation responsive to said filtered ratios, and to output said saturation for caregiver review.