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Signal processing apparatus

  • US RE38,476 E1
  • Filed: 06/27/2002
  • Issued: 03/30/2004
  • Est. Priority Date: 03/07/1991
  • Status: Expired due to Term
First Claim
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1. A system for the enhancement of physiological signals for the measurement of blood oxygen in a subject, the system comprising:

  • first and second light sources to direct light toward the subject, said first and second light sources producing light of first and second wavelengths, respectively;

    a light detector positioned to detect first and second light signals after interacting with the subject and to generate signals indicative of an intensity of said first and second detected light signals, said first detected signal having a first portion arising from light transmitted from said first source and a second portion arising from a first interference source, said second detected signal having a first portion arising from light transmitted from said second source and a second portion arising from a second interference source;

    a storage location containing a mathematical relationship of said first and second portions of said first and second detected signals and a first ratio of said first portion of said first detected signal to said first portion of said second detected signal;

    an analyzer coupled to said storage location to determine a plurality of possible values for said mathematical relationship over a predetermined range of said first ratio; and

    a calculator to determine a selected value from said plurality of possible values for said first ratio based on said plurality of values.

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