Sea Clutter Characteristic Analysis And Target Detection Design Of Medium And Short Range Coast Defence Radar

Radar technology has been widely applied in the maritime field,it is an essential means of sea surface early warning and border defense.Due to the complex environment of the sea surface,sea clutter has significant non-stationary and non-Gaussian properties,which greatly limit the detection of sea surface targets by radar.Therefore,the statistical characteristics of sea clutter and sea surface target detection have always been the focus in the research of coastal defense radar technology.According to the above requirements,this paper studies the statistical characteristics and the modeling and simulating of sea clutter,realizes the detection of weak and small targets on the sea surface by using the time-frequency method,and designs the implementation scheme of radar signal processing flow based on ZYNQ.Firstly,this paper introduces the different amplitude distribution models,power spectrum models and clutter simulation methods of sea clutter.On this basis,we carry out simulation work to get the sea clutter sequences with different amplitude distribution models.Then,the statistical characteristics of sea clutter are analyzed with the measured data.The fitting between the measured sea clutter and different amplitude distribution models is completed by parameter estimation method and goodness of fit test method,and the advantages and disadvantages of different models are compared.The power spectrum estimation of measured sea clutter is achieved through the spectrum estimation method,and the spectrum results are analyzed.Then,the method of time-frequency analysis for weak and small target detection in sea surface is introduced,including short-time Fourier transform,Wigner-Ville distribution and its three deformations.The selection of window length in short-time Fourier transform and the suppression of cross terms in Wigner-Ville distribution are discussed through simulation and analysis.We process the measured data by the time-frequency method,and verify the effectiveness of the time-frequency method in detecting weak and small targets under the background of sea clutter.Finally,the implementation of the coastal defense radar signal processing on hardware platform is introduced.Firstly,the structure,device selection,program framework and clock network of the signal processing system are described;then the implementation process of each algorithm is introduced in modules.In this process,the digital down conversion of twostage extraction structure realized by simple logic is designed to save hardware resources.Secondly,the occupied resources and processing speed of FFT under different structures,multiple multiplication modes and scaling modes are compared,and the appropriate FFT structure is selected to realize pulse compression in frequency domain.Then the DDR3 buffer module is designed to store and read the pulse compression results,and the secondary rearrangement of DDR3 readout data is designed and the moving target detection is realized.Finally,the design and optimization of program for CFAR detection in PS terminal are explained.