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Signal processing apparatus

DC
  • US 7,509,154 B2
  • Filed: 08/20/2007
  • Issued: 03/24/2009
  • Est. Priority Date: 03/07/1991
  • Status: Expired due to Fees
First Claim
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1. A method of measuring oxygen saturation, the method comprising:

  • obtaining first and second signals that are representative of light of first and second wavelengths detected by a light sensitive detector over a period of time, the detected light of first and second wavelengths being attenuated by body tissue carrying pulsing blood;

    transforming the first and second signals into the frequency domain;

    calculating a plurality of possible oxygen saturation values using a plurality of values of each of the transformed first and second signals that correspond to non-zero frequencies;

    selecting one of the plurality of possible oxygen saturation values as an oxygen saturation measurement based upon an analysis to determine which of the plurality of possible oxygen saturation values corresponds to the oxygen saturation of the pulsing blood; and

    outputting the oxygen saturation measurement to a user.

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