Systems and methods for determining respiration information using phase locked loop
AssigneeNellcor Puritan Bennett Ireland
InventorsJames Dripps, James Ochs, Paul S. Addison
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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.
Claims20
A method for determining respiration information, the method comprising:
- receiving a photoplethysmograph (PPG) signal;
- generating, using processing equipment, an oscillator signal;
- adjusting, using the processing equipment, the oscillator signal based on a phase difference between the PPG signal and the oscillator signal;
- generating, using the processing equipment, a demodulated signal based on the PPG signal and the oscillator signal;
- and
- determining, using the processing equipment, the respiration information based on the demodulated signal.
A patient monitoring system comprising:
- an interface configured to receive a photoplethysmograph (PPG) signal;
- a phase detector coupled to the interface;
- an oscillator coupled to the phase detector, wherein the oscillator is configured to adjust the phase of an oscillator signal based on a phase difference between the PPG signal and the oscillator signal;
- and
- a processor configured to:
- generate a demodulated signal based on the PPG signal and the oscillator signal, and
- determine the respiration information based on the demodulated signal.
Dependencies are inferred from the claim text.