Signal processing apparatus
First Claim
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 first and second light signals of first and second wavelengths, respectively;
a light detector positioned to detect said first and second light signals after interaction with the subject and to generate first and second signals indicative of an intensity of said first and second detected light signals, respectively, said first generated 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 generated signal having a first portion arising from light transmitted from said second source and a second portion arising from a second interference source;
an adaptive signal processor having a signal input coupled to said light detector to receive said first generated signal, an adaptive filter having an input to receive a reference signal, and an output, and an error output to generate an error signal, wherein said error output is coupled to said adaptive filter to adjust said adaptive filter so that a function of said error signal has a minimum;
wherein said first and second portions of said first and second generated signals and a first ratio constant have a defined mathematical relationship;
a reference signal generator to generate said reference signal based on a possible value of said first ratio constant; and
a peak detector to receive an output signal from said adaptive signal processor and determine a calculated value for said first ratio constant corresponding to a first peak value of said output signal over a predetermined range of possible ratios, said reference signal generator generating said first portion of said first detected signal and said first portion of said second detected signal based on said mathematical relationship and said calculated value of said first ratio constant.
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Accused Products
Abstract
The present invention involves method and apparatus for analyzing two measured signals that are modeled as containing primary and secondary portions. Coefficients relate the two signals according to a model defined in accordance with the present invention. In one embodiment, the present invention involves utilizing a transformation which evaluates a plurality of possible signal coefficients in order to find appropriate coefficients. Alternatively, the present invention involves using statistical functions or Fourier transform and windowing techniques to determine the coefficients relating to two measured signals. Use of this invention is described in particular detail with respect to blood oximetry measurements.
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Citations
16 Claims
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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:
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first and second light sources to direct light toward the subject, said first and second light sources producing first and second light signals of first and second wavelengths, respectively; a light detector positioned to detect said first and second light signals after interaction with the subject and to generate first and second signals indicative of an intensity of said first and second detected light signals, respectively, said first generated 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 generated signal having a first portion arising from light transmitted from said second source and a second portion arising from a second interference source;an adaptive signal processor having a signal input coupled to said light detector to receive said first generated signal, an adaptive filter having an input to receive a reference signal, and an output, and an error output to generate an error signal, wherein said error output is coupled to said adaptive filter to adjust said adaptive filter so that a function of said error signal has a minimum; wherein said first and second portions of said first and second generated signals and a first ratio constant have a defined mathematical relationship; a reference signal generator to generate said reference signal based on a possible value of said first ratio constant; and a peak detector to receive an output signal from said adaptive signal processor and determine a calculated value for said first ratio constant corresponding to a first peak value of said output signal over a predetermined range of possible ratios, said reference signal generator generating said first portion of said first detected signal and said first portion of said second detected signal based on said mathematical relationship and said calculated value of said first ratio constant. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for the enhancement of physiological signals for the measurement of blood oxygen in a subject, the method comprising the steps of:
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directing light from first and second light sources of different wavelengths toward the subject; detecting signals from said first and second light sources after interaction with the subject and generating first and second signals corresponding to an intensity of said first and second detected signals, respectively, said first generated 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 generated signal having a first portion arising from light transmitted from said second source and a second portion arising from a second interference source; coupling said first generated signal to a signal input of an adaptive signal processor having an adaptive filter having an input to receive a reference signal, and an output, and an error output generating an error signal wherein said error signal is coupled to said adaptive filter to adjust said adaptive filter so that a function of said error signal has a minimum; coupling an output signal from said adaptive signal processor to a peak detector and calculating a first ratio value corresponding to a first detected peak value of said error signal over a predetermined range of possible ratio values; generating a first reference signal based on a mathematical relationship of said first and second portions of said first and second generated signals, and said first ratio value; and coupling said first reference signal to said adaptive filter input wherein said filter output generates an estimate of said first portion of said first generated signal. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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Specification