Improved Heartbeat Detection by Exploiting Temporal Phase Coherency in FMCW Radar

We propose a novel range-bin selection method, temporal phase coherency (TPC), to improve the accuracy of heartbeat extraction by using the frequency-modulated continuous wave (FMCW) radar. The FMCW radar has a range-resolution, and the micro-displacement at each range bin can be analyzed by calculating the phase corresponding to the range. To extract accurate heartbeat signal, selecting the range bin is important. However, the heartbeat signal, whose displacement is minute, is hard to be detected. To select the range bin with accurate heartbeat signal, we quantified the unique characteristic of heartbeat, sinus rhythm, as TPC index. In experimental results, we evaluated the accuracy of extracted heart rates for various subjects and experimental situations. The results showed that the TPC can select the range bin with more accurate heartbeat compared to the conventional methods, indicating that the TPC would be useful for the FMCW radar based vital-sign monitoring.