Heart Rate Tracking Using a Doppler Radar With the Reassigned Joint Time-Frequency Transform

Heart rate variations are tracked using an RF Doppler signal by applying a reassigned joint time-frequency transform (RJTFT). In time-frequency analysis, RJTFT improves the readability of the heart rate on a spectrogram and the heart rate is continuously tracked with it. To verify the result, a heartbeat signal was acquired from a stationary human subject using a Doppler radar unit. The sensor operating at 2.45 GHz was located a distance of 0.5 m from the subject. Using the RJTFT, the heart rate was clearly extracted, thereby improved the readability. A reference heart rate was measured by a photoplethysmography (PPG) device and compared with the heart rate tracked by the RJTFT. The resulting root mean square (RMS) difference of the heart rate measured by the two methods was 5%.