System for measuring the period of a quasi-periodic signal
First Claim
1. A system for measuring the periodic content of an input signal, comprising:
- (A) autocorrelation means, responsive to the input signal, for generating a sequence of autocorrelation functions, each of the autocorrelation functions in the sequence being representative of an autocorrelation function of a portion of the input signal; and
(B) temporal filter means for temporally filtering the autocorrelation functions to generate a lag histogram.
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Accused Products
Abstract
The disclosed system for measuring the periodic content of an input signal includes an autocorrelation function generator for generating a sequence of autocorrelation functions. Each of the autocorrelation functions is representative of an autocorrelation function of a portion of the input signal. The system further includes a temporal filter for filtering the autocorrelation functions and thereby generating a lag histogram.
In other forms the system may comprise a fetal heart rate monitor for measuring the heart rate of a fetus in vivo. The monitor generates a lag histogram and uses the lag histogram for stabilizing the determination of the fetal heart rate.
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Citations
25 Claims
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1. A system for measuring the periodic content of an input signal, comprising:
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(A) autocorrelation means, responsive to the input signal, for generating a sequence of autocorrelation functions, each of the autocorrelation functions in the sequence being representative of an autocorrelation function of a portion of the input signal; and (B) temporal filter means for temporally filtering the autocorrelation functions to generate a lag histogram. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A fetal heart rate monitor for measuring the heart rate of a fetus, comprising:
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(A) means for generating an ultrasound signal that propagates into the fetus; (B) means for receiving an ultrasound reflection signal reflected by the fetus and means for converting the ultrasound reflection signal to an electrical signal; (C) autocorrelation means, responsive to the electric signal, for generating a sequence of autocorrelation functions, each of the autocorrelation functions in the sequence being representative of an autocorrelation function of a portion of the electric signal; and (D) temporal filter means for temporally filtering the autocorrelation functions to generate a lag histogram. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A system for measuring the periodic content of an input signal, comprising:
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(A) autocorrelation means, responsive to the input signal, for generating an autocorrelation function, at any point in time the autocorrelation function being representative of an autocorrelation function of a portion of the input signal; and (B) lag histogram means for generating a lag histogram from the autocorrelation function, the lag histogram means including means for suppressing transitory features in the autocorrelation function so that said transitory features make a relatively small contribution to the lag histogram and means for emphasizing temporally consistent features of the autocorrelation function so that said temporally consistent features make a relatively large contribution to the lag histogram.
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25. A system for measuring the periodic content of an input signal, comprising:
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(A) autocorrelation means, responsive to the input signal, for generating an autocorrelation function, at any point in time the autocorrelation function being representative of an autocorrelation function of a portion of the input signal; and (B) temporal filter means for temporally filtering portions of the autocorrelation function to generate a lag histogram.
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Specification