Millimeter-wave radar for vital signs sensing

Abstract

In this paper, we will describe the development of a 228 GHz heterodyne radar system as a vital signs sensing monitor that can remotely measure respiration and heart rates from distances of 1 to 50 meters. We will discuss the design of the radar system along with several studies of its performance. The system includes the 228 GHz transmitter and heterodyne receiver that are optically coupled to the same 6 inch optical mirror that is used to illuminate the subject under study. Intermediate Frequency (IF) signal processing allows the system to track the phase of the reflected signal through <i>I</i> and <i>Q</i> detection and phase unwrapping. The system monitors the displacement in real time, allowing various studies of its performance to be made. We will review its successes by comparing the measured rates with a wireless health monitor and also describe the challenges of the system.