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Method and apparatus for calibration to reduce coupling between signals in a measurement system

  • US 9,861,305 B1
  • Filed: 08/26/2015
  • Issued: 01/09/2018
  • Est. Priority Date: 10/12/2006
  • Status: Active Grant
First Claim
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1. An apparatus for measuring one or more blood constituents in a subject using a plurality of light emitters configured to emit different wavelengths of light one at a time during physiological measurements, said apparatus comprising:

  • a first light emitter which, during normal operation, emits light of a first wavelength during a first time interval;

    a second light emitter which, during normal operation, emits light of a second wavelength during a second time interval;

    a third light emitter which, during normal operation, emits light of a third wavelength during a third time interval;

    a detector which detects the light emitted by the first, second and third signal sources after attenuation by tissue of a patient, said detector generating a detector output signal responsive to the detected light; and

    a signal processor which receives said detector output signal, said signal processor configured to demodulate said detector output signal by applying a first demodulation signal to a signal responsive to said detector output signal to generate a first demodulator output signal corresponding to the light of the first wavelength, applying a second demodulation signal to said signal responsive to said detector output signal to generate a second demodulator output signal corresponding to the light of the second wavelength, and applying a third demodulation signal to said signal responsive to said detector output signal to generate a third demodulator output signal corresponding to the light of the third wavelength, said signal processor configured to select said first demodulation signal, said second demodulation signal and said third demodulation signal to reduce crosstalk between said first, second, and third demodulator signals using, at least in part, calibration data, wherein said calibration data comprises calibration data from a calibration procedure wherein said first light emitter, said second light emitter, and said third light emitter are operated two at a time during a second modulation operation period.

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