Signal averaging using gating signal obtained from autocorrelation of input signals
First Claim
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1. A method for performing pulse volume measurement on a patient, the method comprising:
- (a) taking a plethysmographic signal from the patient, the plethysmographic signal comprising a plurality of plethysmographic waveforms;
(b) performing an autocorrelation on the plethysmographic signal to determine locations of the individual plethysmographic waveforms;
(c) isolating one of the plethysmographic waveforms in accordance with the autocorrelation;
(d) convolving the isolated plethysmographic waveform with the plethysmographic signal to align the isolated plethysmographic waveform with the plethysmographic signal;
(e) performing signal averaging between the isolated plethysmographic waveform and the plethysmographic signal as aligned in step (d) to provide an averaged signal; and
(f) performing the pulse volume measurement in accordance with the averaged signal.
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Abstract
A plethysmographic or other signal is autocorrelated to give a first-pass determination of the distances among individual waveforms. A waveform is isolated, tested to determine whether its amplitude remains in suitable bounds for signal averaging, and convolved with the signal to match it with the other waveforms for averaging. Thus, a separate gating signal is not needed for signal averaging.
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Citations
22 Claims
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1. A method for performing pulse volume measurement on a patient, the method comprising:
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(a) taking a plethysmographic signal from the patient, the plethysmographic signal comprising a plurality of plethysmographic waveforms; (b) performing an autocorrelation on the plethysmographic signal to determine locations of the individual plethysmographic waveforms; (c) isolating one of the plethysmographic waveforms in accordance with the autocorrelation; (d) convolving the isolated plethysmographic waveform with the plethysmographic signal to align the isolated plethysmographic waveform with the plethysmographic signal; (e) performing signal averaging between the isolated plethysmographic waveform and the plethysmographic signal as aligned in step (d) to provide an averaged signal; and (f) performing the pulse volume measurement in accordance with the averaged signal. - View Dependent Claims (2, 3, 4, 5)
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6. A method for averaging a signal which comprises a plurality of individual waveforms in sequence, the method comprising:
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(a) performing an autocorrelation on the signal to determine locations of the individual waveforms in the signal; (b) isolating one of the waveforms in accordance with the autocorrelation; (c) time-shifting the isolated waveform to align the isolated waveform with another waveform in the signal; and (d) averaging the isolated waveform and the other waveform. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 22)
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16. A system for averaging a signal which comprises a plurality of individual waveforms in sequence, the system comprising:
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an input for receiving the signal; and circuitry, in communication with the input, for; (a) performing an autocorrelation on the signal to determine locations of the individual waveforms in the signal; (b) isolating one of the waveforms in accordance with the autocorrelation; (c) time-shifting the isolated waveform to align the isolated waveform with another waveform in the signal; and (d) averaging the isolated waveform and the other waveform. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification