| Life-detection radar transmits electromagnetic wave into the search and rescue area,and then gets human's localization and vital signs signals by analyzing the echo signals.It plays an important role in homeland security,anti-terrorism,disaster rescue and other fields.Compared with traditional life detectors,such as infra-red,acoustic,and optical,life-detection radar has advantages of good wall penetration characteristics and independent of environment temperature,noise and visibility.So it has become a research focus in life-detection field.Boolean-chaos signal has the characteristics of wide and flat power spectrum,random waveforms and ?-like autocorrelation curve.The centimeterlevel spatial resolution can be obtained utilizing the Boolean-chaos signal for ranging.In addition,the Boolean-chaos signal can be used in the post-disaster complex electromagnetic environments benefiting from the strong anti-jamming ability.In this paper,the Boolean-chaos signal is introduced into the life-detection radar field.We propose a hybrid chaos-Doppler life-detection radar and a wideband Boolean-chaos life-detection radar,respectively.The main research contents include:1.The classification of the existing life detectors is summaried.The classification and research progress of life-detection radar were introduced in detail,and advantages and disadvantages of each were analyzed.Besides,the wideband Boolean-chaos signal was introduced into life-detection radar field.2.Two wideband Boolean-chaos signal generators were introduced.By analyzing the characteristics of Boolean-chaos signal such as time series,spectrum,autocorrelation and ambiguity function,we focused on studying the advantages of Boolean-chaos signal in life-detection radar field.3.A wideband linear tapered slot antenna and a split ring sensor were designed and fabricated.A hybrid chaos-Doppler life-detection radar system which transmitted a wideband Boolean-chaos signal modulated by a sinusoidal wave was constructed.Human location and life signal detection can be obtained simultaneously by using the chaotic correlation method and Michelson interference principle.Experimental results showed that this radar can detect the human target behind a 20-cm-thick wall.The down-range resolution and dynamic range for human location were 23 cm and 50 dB,respectively.The dynamic ranges for respiration and heartbeat detection were 50 dB and 10 dB,respectively.Furthermore,the anti-jamming properties of this radar were demonstrated by electromagnetic simulations.The results showed that the proposed radar possesses excellent jamming immunity to the Gaussian white noise,linear frequency modulation signal and Boolean-chaos signal.4.A wideband Boolean-chaos life-detection radar which transmitted a wideband Boolean-chaos signal was set up.Combining with the location-vital signs extraction algorithm,human's location and respiration frequency were acquired.Simulation and experimental results showed that this system can detect multiple human targets behind a 20-cm-thick wall and has an excellent anti-jamming ability,the anti-jamming performance for the Gaussian white noise and linear frequency modulation signal was better than Boolean-chaos signal under the same interference level. |
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