Ultra-wide band (UWB) pulse Doppler radars provide range-time-frequency information which enables the target localization and vital sign monitoring of a subject. One challenge for UWB radar systems is accurately detecting the heartbeat of a subject, i.e. recording the small displacements of thorax caused by heartbeat due to its poor S/N ratio.
Given that the phase-based algorithms are more robust against noise in heartbeat detection so it could lead to better demodulation of micro displacements. In this paper, two algorithms based on complex signal demodulation and arctangent method are extended here to UWB radars to detect the phase variation of reflected pulses caused by cardiac motions, results will be presented.