Measurement system having pole zero cancellation
First Claim
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1. A pulse rate measuring system for receiving during sample pulse intervals, a pulsed photocurrent signal including an ambient light and a reflected light carrier signal which is amplitude modulated by a heart blood pressure signal comprising:
- signal processing means responsive to said pulsed photocurrent signal and including a second order loop having a first differentiator means providing a transfer function having a high pass pole at a first frequency,cancellation means for forming a zero at said first frequency to cancel the high pass pole of said transfer function; and
second differentiator means coupled to said cancellation means for forming a high pass pole at a second frequency, andadditional pulse-shaping and output means coupled to said second differentiator means.
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Abstract
A pulse IR reflectance plethysmograph system for heart rate measurement and display in a digital watch or as a medical instrument having a novel direct coupled pole zero cancellation circuit that compensates undesirable shaping effects on the heart blood pressure wave. The system utilizes a pulsed LED light emitting diode for transmitting light pulses and a photodiode for receiving light pulses reflecting from a finger.
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6 Claims
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1. A pulse rate measuring system for receiving during sample pulse intervals, a pulsed photocurrent signal including an ambient light and a reflected light carrier signal which is amplitude modulated by a heart blood pressure signal comprising:
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signal processing means responsive to said pulsed photocurrent signal and including a second order loop having a first differentiator means providing a transfer function having a high pass pole at a first frequency, cancellation means for forming a zero at said first frequency to cancel the high pass pole of said transfer function; and second differentiator means coupled to said cancellation means for forming a high pass pole at a second frequency, and additional pulse-shaping and output means coupled to said second differentiator means. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification