Path Loss Compensation Method for Multiple Target Vital Sign Detection with 24-GHz FMCW Radar

Over the past few decades, Doppler radar has attracted attention in biomedical and healthcare applications because of the benefits of a non-contact vital sign sensor. Though Doppler radar has the high sensitivity for physiological signals, multiple target problem is one of the inevitable issue in a non-contact vital sign sensor. In this paper, we proposed a non-contact vital sign sensor for multiple subject based on 24 GHz frequency-modulated continuous-wave (FMCW) radar. Since FMCW radar can extract the range and velocity of the target, it is possible to detect each vital sign by signal separation according to the position of the target. A signal amplitude difference from a plurality of targets is corrected by the signal processing according to the radar equation. The measured results validate the possibility of multiple vital sign sensor. We expect that our proposed method can be feasible to utilize the application such as a driver monitoring system and a medical monitoring system.