Research On Methods Of Weak Target Detection For Full Polarization Radar Based On Echo Feature Recognition

For a long time,the detection and recognition of small and weak targets by radar under the condition of strong clutter has been one of the key and difficult points in the field of radar signal processing.Traditional radar detection methods are difficult to effectively detect targets with low signal-to-clutter ratio(SCR),slow moving speed,and small physical appearance.With the progress of polarization signal processing in theory and engineering technology and the development of new radar application technology,it has greatly expanded and enhanced the radar’s ability and methods to acquire target information.Based on the detailed analysis of the differences in characteristics between the target echo and clutter received by the radar,this article seeks to make full use of these differences to realize the detection of weak and small targets by the radar.The theoretical and practical comparisons of the method could be used for the radar in complex electromagnetic environment.This would benefit in providing new ideas for the difficult problem surrounding the detection of small and weak targets often with faint radar signatures.The main research content of this paper includes the following aspects:1.This paper first briefly summarizes the current research status of domestic and foreign scholars on clutter characteristics,radar dim target detection,and feature-based detection methods.Secondly,it analyzes and introduces the detection theory of radar targets.It analyzes the related theories and hypotheses surrounding radar signal detection and several commonly used constant false alarm detection methods in detail.Simultaneously,it combines simulation data to locate several CFAR detectors.The performance of the CFAR detectors was analyzed and discussed.2.The differences between the pure clutter range resolution unit using radar echo and the target range resolution unit in the time domain,frequency domain,polarization domain,and wavelet domain are discussed in detail based on the measured data.The amplitude distribution characteristic of the clutter has been studied combined with the measured sea clutter data.Comparisons on order moments of the pure clutter range resolution unit and the target range resolution unit under different polarization channels are carried out to analyze the fitting results of the amplitude distribution of the clutter under different polarization channels.This paper studies the optimal fitting distribution model corresponding to different distance resolution units,the time correlation and time correlation of the clutter,and spatial correlation,the echo spectrum and Doppler velocity under different polarization channels.Combined with the measured UAV data,the amplitude distribution characteristics and polarization ratio amplitude and phase characteristics of the ground clutter are analyzed and discussed in detail.This article analyzes and summarizes the difference between the target clutter distance unit and the pure clutter distance unit in different characteristics.3.Using the sensitivity of kurtosis to transient signals,the characteristic of spectral kurtosis is used in radar target detection.Through the analysis of measured sea clutter data and UAV data,it is discovered that pure clutter and target distance unit have differences in spectral kurtosis characteristics.The spectral kurtosis features of the target and clutter distance resolution unit are extracted sequentially in the time-frequency domain and the wavelet domain.Based on the measured data,the analysis shows that the target and clutter distance resolution unit are separated in the spectral kurtosis feature and the radar target detection method based on Morlet wavelet spectral kurtosis is proposed.The five sets of polarization channel correlation coefficients are used to extract the five sets of polarization features combined with the sea clutter measured data,and select one of the features with the best separation between the clutter and the target,thus the radar target detection method is proposed based on the polarization parameter features.The detection performance of the two detectors is analyzed through simulation data and the results show that the two detection methods can both accurate target detection under different clutter backgrounds,which is better than traditional polarization radar target detection methods.The two detection methods proposed in this paper have better detection performance for weak targets,and have certain reference value in the field of radar detection.