A Simple Parameter Estimation Method for Periodic Signals Applicable to Vital Sensing Using Doppler Sensors

A Doppler sensor enables us to detect the movement of objects. It transmits an electro-magnetic wave and receives signals yielded by the reflection at the objects so that we can detect the movement of the objects by measuring the frequency deviation between the transmitted- and the received signals. Recently, it is also drawing attention as a tool of non-contact vital sensing such as heartbeats and breathing. This is particularly interesting as a means for monitoring of patients in hospitals or residents in nursing homes in order to make such facilities more efficient. In this paper, aiming at such application, we propose a new very simple signal processing scheme in order to estimate (1) the number of signals, (2) the period of each signal, and (3) the fundamental waveform. It is also emphasized that the estimations (1)-(3) are available for two signals. The performance is verified through computer simulations