Real-Time Evaluation of Heart Rate and Heart Rate Variability Using Microwave Reflectometry

This paper presents noncontact measurement of vital signals using microwave reflectometry. Elimination of the spurious component due to random movement of human subject has been the biggest problem for microwave measurement. Auto-gain control of the receiver, template matching and cross-correlation technique among multiple reflectometers enable motion artifact elimination, signal peak detection, and data processing for various parameters. We focus here on the real-time measurements of heart rate (HR) and heart rate variability (HRV). Those measurements are performed by both reflectometer and conventional electrocardiograph (ECG) for each other comparison. The evaluation of HR and HRV using microwave reflectometry is completely noninvasive and feasible even through clothing, which is extremely effective to daily life and driver's monitoring.