Displacement Motion Sensing with Asynchronous Bandpass Sampling Using a Single-Channel Dual-PLL SSB low-IF Doppler Radar

In this paper, a displacement motion sensing technique combining asynchronous bandpass sampling and a phase evolution extraction algorithm is proposed for a single-channel dual-phase-locked-loop (PLL) single-sideband (SSB) low-intermediate frequency (IF) Doppler radar. In the proposed technique, asynchronous bandpass sampling is used to shift the raw IF signal spectrum and reduce the sampling rate of the analog-to-digital converter (ADC). Furthermore, the employed phase extraction algorithm can demodulate the single-channel baseband signal of the SSB low-IF radar, which avoids the I/Q mismatch in quadrature demodulation and also reduces the number of ADCs to only one. Theoretical analysis shows the advantages of the proposed technique over existing methods in terms of sampling rate and sampling channels. Finally, experimental results show that the proposed technique can successfully recover the mechanical motion of the actuator and the respiratory and heartbeat motions of the subject.