High Accuracy Heartbeat Detection from CW-Doppler Radar Using Singular Value Decomposition and Matched Filter

• Published in: Sensors (Basel, Switzerland) Vol. 21; no. 11; p. 3588
• Main Authors: Iwata, Yuki, Thanh, Han Trong, Sun, Guanghao, Ishibashi, Koichiro
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 21.05.2021; MDPI
• Subjects: Accuracy; Airports; Biometrics; continuous wave-Doppler radar; Decomposition; Doppler radar; Heart rate; Infectious diseases; matched filtering; Measurement techniques; Noise; non-contact vital signs measurement; Respiration; Signal processing; singular value decomposition; Time series; Vibration
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s21113588

Heart rate measurement using a continuous wave Doppler radar sensor (CW-DRS) has been applied to cases where non-contact detection is required, such as the monitoring of vital signs in home healthcare. However, as a CW-DRS measures the speed of movement of the chest surface, which comprises cardiac and respiratory signals by body motion, extracting cardiac information from the superimposed signal is difficult. Therefore, it is challenging to extract cardiac information from superimposed signals. Herein, we propose a novel method based on a matched filter to solve this problem. The method comprises two processes: adaptive generation of a template via singular value decomposition of a trajectory matrix formed from the measurement signals, and reconstruction by convolution of the generated template and measurement signals. The method is validated using a dataset obtained in two different experiments, i.e., experiments involving supine and seated subject postures. Absolute errors in heart rate and standard deviation of heartbeat interval with references were calculated as 1.93±1.76bpm and 57.0±28.1s for the lying posture, and 9.72±7.86bpm and 81.3±24.3s for the sitting posture.