Contact-free measurement of heartbeat signal via a doppler radar using adaptive filtering

It has been proven that the cardiopulmonary signs, including respiration and heartbeat signal, can be contact-free measured via a Doppler radar. However, the heartbeat signal cannot be identified when the human subject does not hold his or her breath. To resolve the problem, the adaptive noise canceller (ANC) based on recursive-least square (RLS) algorithm is presented to simultaneously measure the heartbeat and the respiration signal. Experimental results showed that not only can the heartbeat signal be well identified, but the heart rate also strongly correlated with that derived from the electrocardiogram (ECG).