Doppler Cardiogram Detection in the Presence of Respiration with a K-band Radar Sensor

In this work, a K-band 24-GHz ac-coupled Doppler radar sensor was designed to measure the Doppler Cardiogram (DCG) in the presence of human respiration. The AC coupling architecture avoids dc-tuning and has simple hardware implementation. In addition, a novel DCG extraction algorithm was proposed to extract the accurate DCG from the Doppler radar signals scattered by the skin of the chest wall with no need for subject holding his/her breath. A PPG sensor was simultaneously employed as the reference. Experimental results show that the DCG obtained in this work is aligned well with the cardiac activities recorded by PPG. It also has many characteristic points which contain the velocity and strength information of the heart, which is highly desirable for long-term personal daily healthcare.