Life Detection And Localization Based On Stepped-frequency Continuous Wave Radar

China is a country with frequent earthquakes.In the last two decades,earthquake disasters in Wenchuan,Yushu,Lushan and other places have caused huge loss of life and property to the local people.With the growth of China's economic level,the requirement for rapid rescue of trapped people in earthquake disasters is also becoming stronger and stronger.The life detection technology that can quickly and accurately find and localize trapped people has become a top priority in research on earthquake rescue.Due to the excellent penetration performance and anti-interference characteristics of electromagnetic waves,living bodies within non-line-of-sight can be effectively detected and localized.Radar life detection technology has gained higher and higher research and application value.Most of the life detection radars currently used in China are single-point detection equipment,which is not suitable for a large area detection,nor can it perform localization tasks.Moreover,in the past research on radar life detection,researchers often focus on extracting life signals with methods such as coherent accumulation,and using the energy as the basis for judging the existence of living bodies.However,this kind of methods face two difficult problems in the multi-target scenario: First,the echo energy of the living body subject to the shadowing effect is so weak that the traditional energy accumulation based detection method may not be able to detect these weak targets,which will cause missed detection;Secondly,the energy accumulation based detection method cannot distinguish the characteristics of different targets and cannot match the same target in different radar channels,resulting in pairing problem and false detection in multi-target scenarios.It is necessary to propose a multi-station radar based collaborative life detection and localization algorithm for large-area,multi-target scenes.The work of this article is mainly carried out from two aspects of detection and localization:For the aspect of detection of multiple living bodies,we firstly discuss and analyze the life detection characteristics,advantages and disadvantages of different kind of radar waveforms,and decide to use step-frequency continuous wave(SFCW)radar as the basis of the life detection.Then,by modeling the life signal in the SFCW radar echo and studying the life detection algorithm based on energy accumulation,we propose a dual-station radar based cross-correlation life detection algorithm based on the similarity of life signals of the same living body from different radars.And we also optimize the algorithm proposed in this paper according to the actual situation.The experimental results show that the algorithm proposed in this paper has excellent detection capabilities,which can be adapted to life detection in various situations,and can solve the problem of the missed detection and the pairing problem.For the aspect of localization with multi-station radars,we design a constant false alarm rate detection method and a target distance extraction method to obtain the distance of the target relative to each radar on the basis of dual-station radar crosscorrelation life detection algorithm.In addition,we study the application of linear least squares and Levenberg-Marquardt method in multi-station radar target localization.And we design simulation experiments to analyze and compare the performances between the two methods.The experimental results show that the Levenberg-Marquardt method has excellent application value and positioning performance in multi-station radar collaborative localization.The research based on the cross correlation of target signals in different channels in this paper provides a new idea of radar life detection and localization,which lays the foundation for the construction of a distributed multi-station radar collaborative life detection system.In-depth advancement of the research in this paper will help to improve the accuracy of rescue when an earthquake disaster occurs,speed up the postearthquake search and rescue of trapped people,protect the safety of people's lives and property,and have important social value.