Digitally assisted low IF architecture for noncontact vital sign detection

Noncontact Doppler vital sign sensor uses the phase modulated signal backscattered by the subjects to estimate their life sign information. Due to the characteristics of vital sign signal, the homodyne architecture has some obvious disadvantages in this application scenario. In this paper, we present a digitally assisted low IF transceiver system. The presented system provides a 15 dB signal-to-noise ratio (SNR) improvement comparing to the homodyne architecture with the same transmitting power. The system is able to tolerate the IF frequency offset and the phase noise of the IF carrier.