Physiological parameter estimation using phase-locked loop

Abstract

A method and device for physiological parameter estimation, such as heart rate estimation, use a phase-locked loop to dynamically track a dominant frequency of an acoustic signal within a frequency band for the physiological parameter and estimate the physiological parameter using the dominant frequency. Because the phase-locked loop starts searching for the current dominant frequency near the most recently identified dominant frequency, the method and device rapidly incorporate slow changes in the dominant frequency that likely reflect real changes in the monitored physiological parameter while being slow to incorporate rapid changes in the dominant frequency that are likely caused by large noise. The hysteresis in phase-locked loop tracking allows the method and device to avoid physiological parameter estimation error induced by short-term large noise and quickly reacquire the dominant frequency once short-term large noise abates.