Signal processing apparatus
First Claim
1. In combination:
- a detector responsive to a first signal which travels along a first propagation path and a second signal which travels along a second propagation path, to provide a representation of said first and said second signals on an output, a portion of said first and second propagation paths being located in the same propagation medium, wherein said representation of said first signal on said output has a primary signal portion and a secondary signal portion, said primary signal portion of said first signal being subject to attenuation along substantially the entire first propagation path and wherein said representation of said second signal on said output has a primary signal portion and a secondary signal portion, said primary signal portion of said second signal being subject to attenuation along substantially the entire second propagation path; and
a first signal processor having inputs coupled to said detector, said first signal processor responsive to said representation of said first and second signals from said detector to combine said first and second signals to generate either a primary or secondary reference signal which is a function significantly of either of, respectively, said primary or said secondary signal portions of said first and second signals.
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Abstract
A signal processor which acquires a first signal, including a first primary signal portion and a first secondary signal portion, and a second signal, including a second primary signal portion and a second secondary signal portion, wherein the first and second primary signal portions are correlated. The signals may be acquired by propagating energy through a medium and measuring an attenuated signal after transmission or reflection. Alternatively, the signals may be acquired by measuring energy generated by the medium. A processor of the present invention generates a primary or secondary reference signal which is a combination, respectively, of only the primary or secondary signal portions. The secondary reference signal is then used to remove the secondary portion of each of the first and second measured signals via a correlation canceler, such as an adaptive noise canceler, preferably of the joint process estimator type. The primary reference signal is used to remove the primary portion of each of the first and second measured signals via a correlation canceler. The processor of the present invention may be employed in conjunction with a correlation canceler in physiological monitors wherein the known properties of energy attenuation through a medium are used to determine physiological characteristics of the medium. Many physiological conditions, such as the pulse, or blood pressure of a patient or the concentration of a constituent in a medium, can be determined from the primary or secondary portions of the signal after other signal portion is removed.
1557 Citations
24 Claims
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1. In combination:
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a detector responsive to a first signal which travels along a first propagation path and a second signal which travels along a second propagation path, to provide a representation of said first and said second signals on an output, a portion of said first and second propagation paths being located in the same propagation medium, wherein said representation of said first signal on said output has a primary signal portion and a secondary signal portion, said primary signal portion of said first signal being subject to attenuation along substantially the entire first propagation path and wherein said representation of said second signal on said output has a primary signal portion and a secondary signal portion, said primary signal portion of said second signal being subject to attenuation along substantially the entire second propagation path; and a first signal processor having inputs coupled to said detector, said first signal processor responsive to said representation of said first and second signals from said detector to combine said first and second signals to generate either a primary or secondary reference signal which is a function significantly of either of, respectively, said primary or said secondary signal portions of said first and second signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An apparatus for computing arterial and venous signals in living tissue, said apparatus comprising:
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a detector configured to receive a first signal which travels along a first propagation path and a second signal which travels along a second propagation path, at least a portion of said first and second propagation paths being located in a propagation medium, wherein said first signal has an arterial signal portion that is indicative of arterial blood and another signal portion that is indicative of venous blood, and said second signal has an arterial signal portion that is indicative of arterial blood and another signal portion that is indicative of venous blood; and signal processor means having an input coupled to said detector and responsive to said first and second signals and to combine said first and second signals to generate a signal having a significant component which is a function of either of said arterial or said other signal portions of said first and second signal. - View Dependent Claims (20)
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21. A signal processor comprising:
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a detector responsive to a first signal which travels along a first propagation path and a second signal which travels along a second propagation path, to provide a representation of said first and said second signals on an output, at least a portion of said first and second propagation paths being located in the same propagation medium, wherein said representation of said first signal on said output has a primary signal portion and a secondary signal portion, and wherein said representation of said second signal on said output has a primary signal portion and a secondary signal portion; a first signal processor having inputs coupled to said detector, said first signal processor responsive to said representations of said first and second signals from said detector to combine said first and second signals to generate either a primary or secondary reference signal which is a function significantly of either of, respectively, said primary or said secondary signal portions of said first and second signals; and a second signal processor responsive to the secondary reference signal and to said representation of said first signal to derive therefrom an output signal which is a function of significantly said primary signal portion of said first signal.
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22. A signal processor comprising:
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a detector responsive to a first signal which travels along a first propagation path and a second signal which travels along a second propagation path, to provide a representation of said first and said second signals on an output, at least a portion of said first and second propagation paths being located in the same propagation medium, wherein said representation of said first signal on said output has a primary signal portion and a secondary signal portion, and wherein said representation of said second signal on said output has a primary signal portion and a secondary signal portion; a first signal processor having inputs coupled to said detector, said first signal processor responsive to said representations of said first and second signals from said detector to combine said first and second signals to generate either a primary or secondary reference signal which is a function significantly of either of, respectively, said primary or said secondary signal portions of said first and second signals; and a second signal processor responsive to said primary reference signal and to said representation of said first signal to derive therefrom an output signal which is a function significantly of said secondary signal portion of said first signal.
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23. A signal processor comprising:
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a detector responsive to a first signal which travels along a first propagation path and a second signal which travels along a second propagation path, to provide a representation of said first and said second signals on an output, at least a portion of said first and second propagation paths being located in the same propagation medium, wherein said representation of said first signal on said output has a primary signal portion and a secondary signal portion, and wherein said representation of said second signal on said output has a primary signal portion and a secondary signal portion; a first signal processor having inputs coupled to said detector, said first signal processor responsive to said representations of said first and second signals from said detector to combine said first and second signals to generate either a primary or secondary reference signal which is a function significantly of either of, respectively, said primary or said secondary signal portions of said first and second signals; and a second signal processor responsive to said secondary reference signal and to said representation of said first signal to derive therefrom an output signal which is a function significantly of said primary signal portion of said second signal.
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24. A signal processor comprising:
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a detector responsive to a first signal which travels along a first propagation path and a second signal which travels along a second propagation path, to provide a representation of said first and said second signals on an output, at least a portion of said first and second propagation paths being located in the same propagation medium, wherein said representation of said first signal on said output has a primary signal portion and a secondary signal portion, and wherein said representation of said second signal on said output has a primary signal portion and a secondary signal portion; a first signal processor having inputs coupled to said detector, said first signal processor responsive to said representations of said first and second signals from said detector to combine said first and second signals to generate either a primary or secondary reference signal which is a function significantly of either of, respectively, said primary or said secondary signal portions of said first and second signals; and a second signal processor responsive to said secondary reference signal and to said representation of said first signal to derive therefrom an output signal having a significant component which is a function of said secondary signal portion of said second signal.
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Specification