On the Estimation of the Radial Distance of a Moving Person in Indoor Environments from the Demodulated Response of LFMCW Radars

This paper deals with the estimation of the time-variant (TV) radial distance of a moving person in an indoor environment. The TV radial distance is obtained from the amplitude of the demodulated TV radar response. For simplicity, the body of a person is modelled by a single point scatterer. We start by determining the TV path delay caused by the motion of the person. Then, the TV radial distance is deduced from the estimated TV path delay. To confirm the validity of the estimation method, we conduct real-world measurements. In this regard, two experiments are carried out for which the radio-frequency (RF) data is collected using the Ancortek SDR-KIT 2400T2R4 radar system operating at 24GHz. In the first experiment, we consider a swinging pendulum acting as a single moving point scatterer. We compare the estimated TV radial distance of the pendulum with the corresponding theoretical expression that provides the ground truth information. For this experiment, the good match between the measured and analytical results demonstrates the proof of concept. In the second experiment, we consider a walking person acting as a single moving for which we can accurately compute the total travelled distance. The findings confirm the validity of the estimation method.