A spectrum estimation approach for accurate heartbeat detection using Doppler radar based on combination of FTPR and TWV

Non-contact heartbeat detection using Doppler radar is extremely valuable for remotely monitoring and medical diagnosis on special occasions. Nevertheless, fast and accurate heart rate (HR) detection endures several challenges due to influential respiration interference and insufficient frequency spectrum resolution. In this paper, a novel heartbeat detection method with a compact Doppler radar is employed to accurately estimate some indicators of HR and heart rate variability. Firstly, a multiresolution analysis approach based on maximal overlap discrete wavelet transform is introduced to accomplish the preliminary separation of respiration and heartbeat. Subsequently, a template matched filter algorithm is further implemented to maximize the enhancement of the concealed heartbeat component and retrieve the heartbeat signal. Eventually, a novel spectrum estimation method combining frequency-time phase regression with time-window-variation technology is proposed to evaluate the real-time HR. It solves serious dominant frequency estimation deviation and insufficient frequency spectrum resolution in short-period time windows. The accuracy and timeliness of our proposed method are validated by 6 sets of experimental data sampled at the actual office. As a result, the HR detection accuracy is up to 99.70% in different-period time windows of 10 s and 92.09% in 3s. In addition, the mean relative error of extracted beat-to-beat intervals in 3 s ranges from 0.76 to 1.02%.