Study Of Slow And Weak Target Detection And Tracking Algorithm On LFMCW Radar

Due to slow and weak target has been widely used in military and civilian aspects,for example,with the development of science and technology and people living standard rise,civil unmanned aerial vehicle(uav)rotorcraft due to get convenient,easy to use and show explosive growth,the class in aerial drones,entertainment and other fields has been widely used,while brings the industrial upgrading,there have been at the airport and so on a no-fly zone "black fly" all kinds of security threats,thus to uav this kind of radar target in the air security monitoring is of great significance.Linear Frequency Modulated Continuous Wave(LFMCW)radar has the advantages of simple structure,high range resolution and no range blind area,which plays an important role in the field of ground reconnaissance.In this paper,LFMCW radar is used to carry out research on the detection and tracking algorithm of slow small targets,and the research content is realized through hardware platform.The main work contents are as follows:(1)The signal processing technology of LFMCW radar is studied.According to the system structure of LFMCW radar,the basic working principle and signal processing mode of symmetrical triangle LFMCW radar are analyzed.The mathematical expressions of transmit signal,echo signal and beat signal of symmetrical triangular LFMCW radar are derived.This paper introduces the calculation method of radar's target state parameters,including ranging,velocity measurement,amplitude sum difference monopulse angle measurement.The radar ambiguity function of symmetrical triangular FMCW signal is analyzed.The simulation results show that the radar parameters set in this subject can have high two-dimensional resolution to the target.(2)The detection technology of LFMCW radar with slow and weak target is studied.Because the radar cross-section of slow and weak target is small and the detection environment of radar is complex,there are a lot of noise and low frequency clutter in the radar echo of slow target,which causes some trouble to radar target detection.In this paper,the hamming window function and the coherent accumulation method are selected to realize the radar moving target detection process.Then,the detection results are processed by two-dimensional constant false alarm rate detection algorithm.The simulation experiment shows that the processing process can effectively improve the detection performance of the radar to the slow and weak targets.The static target is suppressed in radar target detection results by using the dynamic target display technology.This paper presents a method of radar signal noise suppression based on wavelet analysis.The simulation results show that the method can improve the performance of radar target detection in low SNR.(3)The tracking technology of LFMCW radar with slow and weak target is studied.Because of the maneuverability of the slow and weak target,this paper introduces the motion model of the radar slow and weak target,and establishes the state equation and measurement equation of the moving target.The influence of coordinate conversion error on radar tracking performance is analyzed,and the formula of unbiased coordinate conversion is given.Aiming at the problem of the poor performance of kalman filter algorithm in tracking maneuvering targets,an interactive multi model algorithm based on unbiased estimation is proposed.The Monte Carlo simulation results show that the algorithm has a small estimation error for the maneuvering target and can effectively track the slow and weak target.In view of the problem that the tracking error will increase due to the lag of the switching process between the models of the standard interactive multi model algorithm in the maneuvering of the target,an interactive multi model algorithm based on the adaptive state transfer probability matrix is proposed.The simulation results show that the modified algorithm can effectively reduce the standard deviation of tracking error and improve the tracking accuracy of the target.At the same time,the applicability of the improved algorithm is pointed out.(4)The software of LFMCW radar system is designed and implemented based on hardware platform.According to the functional requirements of the radar system,the upper computer application program of the radar system based on Qt is designed.The detection and tracking algorithm studied in this paper is designed in DSP(TMS320C6678).The detection and tracking performance of the radar system for slow and weak target is tested through the field environment experiment,and the feasibility of the detection and tracking algorithm is analyzed by using the measured data.The results show that the radar system can detect and track the slow and weak target by using the research method in this paper.