Electronic Science and Technology ›› 2021, Vol. 34 ›› Issue (6): 23-27.doi: 10.16180/j.cnki.issn1007-7820.2021.06.004

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A Vital Sign Detection Radar Based on Complex Signal Demodulation

TAI Fanbin,LIU Yun,ZHOU Wen,HANG Xuelian,QIAN Zhicheng,LIU Jixuan,WANG Xingshuai,MA Jiaju   

  1. College of Electronic and Information Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 211106,China
  • Received:2020-02-22 Online:2021-06-15 Published:2021-06-01
  • Supported by:
    Jiangsu Natural Science Foundation(BK20181290);Open Project of State Key Laboratory of Millimeter Wave(K201919)


The radar sensor system has a good prospect in the detection of vital signs of special objects such as infants and burned patients for its advantages of non-contact, concealment and all-weather measurement. In this paper, a design of Doppler radar system based on complex signal demodulation is proposed for the effect of null point issue and the dc offset. The complex signal consisted of the two baseband signals output from the zero-IF quadrature demodulation structure is performed fast Fourier transform to obtain the vital sign of the object. The test shows that when the system works at the center frequency of 2.45 GHz, the frequency of respiration and heartbeat are respectively about 0.3 Hz and 1.1 Hz, which meet the design expectation.

Key words: vital sign detection, Doppler radar, null point, dc offset, zero-IF, quadrature demodulation, complex demodulation, fast Fourier transform

CLC Number: 

  • TN959