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Methods and systems for determining physiological information using reference waveforms

  • US 9,119,598 B2
  • Filed: 09/11/2012
  • Issued: 09/01/2015
  • Est. Priority Date: 09/11/2012
  • Status: Active Grant
First Claim
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1. A subject monitoring system for determining physiological information of a subject, comprising:

  • a sensor configured to generate a photoplethysmograph signal, wherein the sensor detects light attenuated by the subject; and

    processing equipment coupled to the sensor, wherein the processing equipment is configured to;

    calculate a correlation sequence based on a portion of the photoplethysmograph signal and a stored reference waveform;

    determine physiological rate information based on the correlation sequence;

    select a new reference waveform that is derived from the photoplethysmograph signal, wherein a size of the new reference waveform is selected based on a period associated with the physiological rate information;

    determine whether to qualify the new reference waveform; and

    when the new reference waveform is qualified,store the new reference waveform;

    calculate a subsequent correlation sequence based on a more recent portion of the photoplethysmograph signal and the new reference waveform; and

    determine subsequent physiological rate information based on the subsequent correlation sequence.

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