Sensor Nodes for Doppler Radar Measurements of Life Signs

Human life signs can be detected at a distance using mono-static Doppler radars operating in the CW mode. Phase stability of the measurement system plays an important role in successful life signs detection. In this paper it will be shown that small unwanted mechanical motions of the transmit antenna, result in unrecoverable phase errors in the received signal. To overcome this issue, we propose to use a bi-static radar with a sensor node receiver placed in the vicinity of the human subject. Theoretical and experimental results confirm the benefits of using sensor nodes.