Novel signal processing techniques for Doppler radar cardiopulmonary sensing

In this paper, we develop new signal processing techniques for Doppler radar cardiopulmonary sensing. These techniques enable independent recovery of respiration and heartbeat signals from measurements of chest-wall dynamic motion, which are subsequently used for independent estimation of respiration and heart rate. In particular, three novel elements are introduced: the concept of representing the composite demodulated signal in the complex plane as a vector sum of various components, combining dc coupling with block mean removal, and adaptive cancellation of respiration harmonics. From this, algorithms are derived for arc-length demodulation and cardio/pulmonary separation. A test signal generator is developed to simulate actual signals. Also, an experimental setup is presented and several sets of real data are analyzed using the new signal processing techniques.