Instantaneous heartbeat detection using a cross-correlation based template matching for continuous wave radar systems

Instantaneous heartbeat detection is necessary for an optimal patient monitoring in healthcare centers. Whereas electrocardiogram (ECG) and ballistocardiogram (BCG), for instance, are established methods for real time monitoring nowadays, contact-free systems are appreciated. Herewith, a 24 GHz continuous wave (CW) radar system with an intelligent signal processing is presented. Common heartbeat detection algorithms use the fast Fourier transform (FFT), and therefore require an adequate observation time window and rather detect an averaged heart rate. The proposed algorithm in contrast accomplishes the detection of single heart beats directly in the time domain with an insignificant delay. The core of that algorithm is a template matching using the cross-correlation method. In this paper, after describing the radar system with the novel signal processing, the presented system is compared to a commercial ECG product.