Detection of Vital Signs Using Noncoherent Receivers

This work introduces a novel concept for detecting displacements, specifically vital signs resulting from physiological activity, using noncoherent receivers. A theoretical analysis of phase noise propagation in the receiver architecture reveals that individual uncorrelated phase noise contributions add at the intermediate frequency, thereby defining the detection sensitivity. System validation using a reflector mounted on a modulator producing controlled oscillations demonstrates the ability to detect sub-millimeter displacements, provided the residual phase noise from the uncorrelated oscillators remains low. Extending this concept, the system accurately detects respiration and cardiac activity, with results is comparable to those of a reference ECG sensor. These findings open new possibilities for multistatic vital sign detection systems, offering reliable, non-contact sensing for healthcare and remote monitoring applications.