Signal processing apparatus and method
First Claim
1. A signal processing apparatus comprising:
- detector means for receiving a first signal which travels along a first propagation path and a second signal which travels along a second path, said detector comprising a light sensitive sensor configured to detect a physiological function, wherein said first signal has a first desired signal portion and a first undesired signal portion, and said second signal has a second desired signal portion and a second undesired signal portion; and
reference processor means having an input for receiving said first and second signals for combining said first and second signals to generate a reference signal having a primary component which is a function of said first and said second undesired signal portions.
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Accused Products
Abstract
A signal processor which acquires a first signal, including a first desired signal portion and a first undesired signal portion, and a second signal, including a second desired signal portion and a second undesired signal portion, wherein the first and second desired 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 generates a noise reference signal which is a combination of only the undesired signal portions and is correlated to both the first and second undesired signal portions. The noise reference signal is then used to remove the undesired portion of each of the first and second measured signals via an adaptive noise canceler, preferably of the joint process estimator type. The processor may be employed in conjunction with an adaptive noise 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 of a patient or the concentration of a constituent in a medium, can be determined from the desired portion of the signal after undesired signal portions, such as those caused by erratic motion, are removed.
1747 Citations
35 Claims
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1. A signal processing apparatus comprising:
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detector means for receiving a first signal which travels along a first propagation path and a second signal which travels along a second path, said detector comprising a light sensitive sensor configured to detect a physiological function, wherein said first signal has a first desired signal portion and a first undesired signal portion, and said second signal has a second desired signal portion and a second undesired signal portion; and reference processor means having an input for receiving said first and second signals for combining said first and second signals to generate a reference signal having a primary component which is a function of said first and said second undesired signal portions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An in vivo monitoring apparatus comprising:
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light sensitive detector means for receiving a first in vivo signal and a second in vivo signal, wherein said first signal has a first desired signal portion and a first undesired signal portion and said second signal has a second desired signal portion and a second undesired signal portion; and reference processors means having an input for receiving said first and second signals for combining said first and second signals to generate a reference signal having a primary component which is a function of said first and said second undesired signal portions. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An apparatus for measuring a blood constituent comprising:
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energy source means for directing a plurality of predetermined wavelengths of electromagnetic energy upon a specimen; detector means for receiving said plurality of predetermined wavelengths of electromagnetic energy from said specimen and producing electrical signals corresponding to said predetermined wavelengths in response thereto, wherein at least two of said electrical signals each has a desired signal portion and an undesired signal portion; and reference processor means having an input for receiving said electrical signals for combining said electrical signals to generate a reference signal having a primary component which is derived from said undesired signal portions. - View Dependent Claims (18, 19, 20, 21)
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22. A blood gas monitor for non-invasively measuring a blood constituent in a body comprising:
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light source means for directing at least two predetermined wavelengths of light upon a body; detector means for receiving said light from said body and, in response thereto, producing at least two electrical signals corresponding to said at least two predetermined wavelengths of light, wherein said at least two electrical signals each has a desired signal portion and an undesired signal portion; and reference processor means having an input for receiving said at least two electrical signals for combining said at least two electrical signals to generate a reference signal with a primary component which is derived from said undesired signal portions. - View Dependent Claims (23, 24, 25, 26)
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27. An apparatus for processing an amplitude modulated signal having a signal amplitude complicating feature comprising:
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energy source means for directing electromagnetic energy upon a specimen; detector means for acquiring a first amplitude modulated signal and a second amplitude modulated signal, wherein each of said first and second amplitude modulated signals has a component containing information about the attenuation of electromagnetic energy by the specimen and a signal amplitude complicating feature; reference processor means for receiving said first and second amplitude modulated signals and deriving therefrom a noise reference signal which is correlated with the signal amplitude complicating feature; and adaptive noise canceler means having a signal input for receiving said first amplitude modulated signal and a noise reference input for receiving said noise reference signal, said adaptive noise canceler means producing an output signal having a primary component which is derived from said component containing information about the attenuation of electromagnetic energy by the specimen. - View Dependent Claims (28, 29)
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30. An apparatus for extracting a plethysmographic waveform from an amplitude modulated signal having a signal amplitude complicating feature comprising:
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light source means for transmitting light into an organism; detector means for monitoring light from said organism to produce a first light attenuation signal and a second light attenuation signal, wherein each of said first and second light attenuation signals has a component which is representative of a plethysmographic waveform and a component which is representative of the signal amplitude complicating feature; reference processor means for receiving said first and second light attenuation signals and deriving therefrom a noise reference signal, wherein said noise reference signal and said signal amplitude complicating feature each has a frequency spectrum, said frequency spectrum of said noise reference signal being correlated with the frequency spectrum of said signal amplitude complicating feature; and adaptive noise canceler means having a signal input for receiving said first attenuation signal and a noise reference input for receiving said noise reference signal, said adaptive noise canceler means producing an output signal having a primary component which is derived from said component which is representative of a plethysmographic waveform. - View Dependent Claims (31, 32)
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33. A signal processing apparatus having a source of first and second signals, said apparatus comprising:
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a detector which receives said first signal after propation through a test medium to form a first received signal and said second signal after propagation through said test medium to form a second received signal, wherein said first received signal has a first desired signal portion and a second undesired signal portion, and said second received signal has a first desired sigal portion and a second undesired signal portion, wherein a first ratio of the first desired signal portion to said first undesired signal portion has a value ranging from less than one to greater than one, and a second ratio of said second desired signal portion to said second undesired signal portion has a value ranging from less than one to greater than one; and a reference processor coupled to said detector and responsive to said first received signal and said second received signal, said processor comprising a filter which combines said first and second received signals and generates a second reference signal that for any value of said first and second ratios, has a primary component which is a function of said first and said second undesired signal portions.
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34. A signal processing apparatus having a source of first and second signals, said apparatus comprising:
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a detector which receives said first signal after said first signal has propagated through a test medium to form a first received signal and which receives said second signal after said second signal has propagated through said test medium to form a second received signal, wherein said first received signal has a first desired signal portion and a first undesired signal portion, and said second received signal has a second desired signal portion and a second undesired signal portion, wherein a first ratio of the first desired signal portion to said first undesired signal portion has a value ranging from less than one to greater than one, and a second ratio of said second desired signal portion and said second undesired signal portion has a value ranging from less than one to greater than one; and a reference processor coupled to said detector and resopnsive to said first received signal and said econd received signal, said reference processor comprising a filter which combines said first and said second received signal and generates a reference signal that, for any value of said first and second ratios, has a primary component which is a function of said first and said second undesired signal portions.
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35. A signal processing apparatus having a source of first and second signals, said apparatus comprising:
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a detector which receives said first signal after propagation through a test medium to provide a first received signal and which receives said second signal after propagation through said test medium to provide a second received signal, said first received signal having a first ratio between a magnitude of a first desired signal portion and a magnitude of a first undesired signal portion, and said second received signal having a second ratio between a magnitude of a second desired signal portion and a magnitude of a second undesired signal portion; and a reference processor coupled to said detector and responsive to said first and second received signals, said reference processor comprising a filter which combines said first and second received signals and which generates from said first and second received signals a reference signal that, irrespective of said first and second ratios, has a primary component which is a function of said first and said second undesired signal portions.
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Specification