Local Pulse Wave Detection Using Continuous Wave Radar Systems

Although a lot of research has been done into radar-based heartbeat detection over the past few years, it is still unknown which physiological effects truly underlie these measurement signals. This paper investigates the cardiovascular system, as well as the effects due to the antenna characteristics, and establishes a connection to the variety of heartbeat signals that can be found in comparable publications. For the first time, the cause of the diverging signal shapes is researched, revealing the locally specific pulse wave curves named sphygmograms. Three different types are investigated: the carotid, the venous, and the ventricle sphygmogram. Verification of the measured signal shapes is ensured by a laser sensor. Afterward, the influence of the filtering on the sphygmograms is researched, as well as the influence of the antenna characteristics on the radar signal. Finally, all novel insights are combined to substantiate the variety of published heartbeat signal curves.