SYSTEMS AND METHODS FOR DETERMINING RESPIRATION INFORMATION USING PHASE LOCKED LOOP
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Abstract
A patient monitoring system may receive a physiological signal such as a photoplethysmograph (PPG) signal that exhibits frequency and amplitude modulation based on respiration. A phase locked loop may generate a frequency demodulated signal and an amplitude demodulated signal from the PPG signal. An autocorrelation sequence may be generated for each of the frequency demodulated signal and the amplitude demodulated signal. The autocorrelation sequences may be combined and respiration information may be determined based on the combined autocorrelation sequence.
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Citations
31 Claims
- 1. -20. (canceled)
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21. A method for determining respiration information using a patient monitor, the method comprising:
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receiving a photoplethysmograph (PPG) signal; generating, using the patient monitor, an oscillator signal; generating, using the patient monitor, a phase-shifted oscillator signal based on a phase difference between the PPG signal and the oscillator signal; generating, using the patient monitor, an amplitude demodulated signal by multiplying the phase-shifted oscillator signal and the PPG signal; determining, using the patient monitor, the respiration information based on the amplitude demodulated signal; and displaying, using a display, the respiration information.
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31. A patient monitor for determining respiration information, the patient monitor comprising:
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an interface configured to receive a photoplethysmograph (PPG) signal; an oscillator configured to generate an oscillator signal; a processor configured to; generate a phase-shifted oscillator signal based on a phase difference between the PPG signal and the oscillator signal; generate an amplitude demodulated signal by multiplying the phase-shifted oscillator signal and the PPG signal; and determine respiration information based on the amplitude demodulated signal; and a display configured to display the respiration information.
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Specification