Center Tracking Quadrature Demodulation for a Doppler Radar Motion Detector

Quadrature direct-conversion microwave Doppler radar enables accurate remote detection of cardiopulmonary activity. One challenge for such detection is DC offset resulting from receiver imperfections and clutter. In the paper we propose a novel DC offset compensation method that takes into account all clutter signals including those from stationary parts of the human subject. This techniques was proven effective for detection of heart rate with a high degree of accuracy for a stationary subject. In addition, same technique was used for successful demodulation of large motion, including a subject walking with two meters of total displacement.