Multi-frequency sensor for remote measurement of breath and heartbeat

Remote measurement of breath and heartbeat is desirable in many situations. It avoids the discomfort resulting from electrodes applied on the skin for long-term patients or during sports acvtivities. Also, surveillance of high security areas or finding survivors of disasters are interesting applications. Common methods identify the movement of heart and thorax by using the range resolution provided by UWB pulse radar systems. In this paper a low-cost approach is presented, that is based on detection of movement by means of Doppler radar sensors. Combining three sensors working in the ISM bands at 433 MHz, 2.4 GHz and 24 GHz, the presence of persons was reliably detected and the frequency of breath and heartbeat was measured.