This paper proposes a RF-switch-based radar system for detecting multi-target and multi-direction vital sign simultaneously. Compared to traditional continuous wave (CW) radars which suffer mixed and distorted phases from multiple reflections, frequency modulation continuous wave (FMCW) radars have the nature of suitable range resolution and the inherent capabilities of multi-target monitoring. By using FMCW radars to extract vital signs separately based on our proposed algorithm, the vital sign of the two targets can be detected simultaneously even within the limitation of the resolution bin. Furthermore, adding a RF switch, as a multiplexer, enables a single transceiver to detect the vital signs from multiple directions and multiple targets straightforward. Moreover, this RF switch provides the mixing function. A low-IF architecture is proposed and demonstrated for multi-direction vital sign detection simultaneously, and the signal to noise ratio (SNR) can be improved by choosing IF properly to reduce the flicker noise. The demodulation of heart rate (HR) is challenge due to low SNR and the harmonic of respiratory rate (RR) for FMCW vital sign radars. We apply an ensemble empirical mode decomposition (EEMD) algorithm to extract intrinsic mode functions of RR and HR. Experiments show the proposed algorithm improve SNR and accuracy significantly.
|Journal||IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology|
|Publication status||Accepted/In press - 2020 Jan 1|
All Science Journal Classification (ASJC) codes
- Radiology Nuclear Medicine and imaging