 Universal/upgrading pulse oximeter |
| FIG. 1 illustrates a prior art pulse oximeter 100 and associated sensor 110. Conventionally, a ... |
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| Pulse oximetry pulse indicator |
| FIG. 1 illustrates the standard plethysmograph waveform 100, which can be derived from a pulse ... |
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| Method and apparatus for demodulating signals in a pulse oximetry system |
| The present invention avoids the problems associated with conventional demodulation and separation ... |
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| Pulse oximeter probe-off detector |
| To compute peripheral arterial oxygen saturation, denoted SP.sub.a O.sub.2, pulse oximetry relies ... |
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| Sensor wrap including foldable applicator |
| Accordingly, one aspect of the present invention is to provide a reusable/disposable (resposable) ... |
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| Pulse oximetry data confidence indicator |
| FIG. 1 illustrates the standard plethysmograph waveform 100, which can be derived from a pulse ... |
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| Low power pulse oximeter |
| Increasingly, pulse oximeters are being utilized in portable, battery-operated applications. For ... |
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| Stereo pulse oximeter |
| Prior art invasive oxygen assessment techniques are inherently limited. Specifically, in vitro ... |
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| Signal processing apparatus |
| This invention provides improvements upon the methods and apparatus disclosed in U.S. patent ... |
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| Dual-mode pulse oximeter |
| FIG. 1 illustrates a prior art pulse oximeter 100 and associated sensor 110. Conventionally, a ... |
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Signal processing apparatus
| Details |
Inventors: Diab, Mohamed K.; Kiani, Massi E.; Weber, Walter M;
Assignee: Masimo Corporation (Irvine, CA)
Primary Examiner: Winakur; Eric F.
Assistant Examiner:
Attorney, Agent or Firm: Knobbe, Martens, Olson & Bear, LLP
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. |
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DETAILED DESCRIPTION This invention is an improvement of U.
S.
Patent application Ser.
No.
07/666,060 filed Mar.
7, 1991 and entitled Signal Processing Apparatus and Method, which earlier application has been assigned to the assignee of the instant application.
The invention is a signal processor which acquires a first signal and a second signal that is correlated to the first signal.
The first signal comprises a first primary signal portion and a first secondary signal portion.
The second signal comprises a second primary signal portion and a second secondary signal portion.
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.
The first and second measured signals are processed to generate a secondary reference which does not contain the primary signal portions from either of the first or second measured signals.
The remaining secondary signal portions from the first and second measured signals are combined to form the secondary reference.
This secondary reference is correlated to the secondary signal portion of each of the first and second measured signals.
The secondary reference 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.
The correlation canceler is a device which takes a first and second input and removes from the first input all signal components which are correlated to the second input.
Any unit which performs or nearly performs this function is herein considered to be a correlation canceler.
An adaptive correlation canceler can be described by analogy to a dynamic multiple notch filter which dynamically changes its transfer function in response to a reference signal and the measured signals to remove frequencies from the measured signals that are also present in the reference signal.
Thus, a typical adaptive correlation canceler receives the signal from which it is desired to remove a component and a reference signal
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Communications 
