Dynamic Sea-surface Echo Simulation And Characteristic Analysis For Missile-borne Radar

In the application of sea target detection,the background clutter resulted from sea surface scattering echoes severely restricts the detectability of interested targets from or near the sea surface.In order to improve target detection performance in the sea background,it is necessary to study the electromagnetic scattering characteristics of sea clutter.Therefore,the influence of various clutter characteristics on target detection can be reduced.However,due to factors such as the poor test conditions and the variety of scenes,the acquisition of real data is difficult and expensive.For this reason,it is economical and practical to obtain sea clutter data based on modeling and simulation.To sum up,based on the accurate modeling and simulation of sea echo of missile-borne radar,characteristics of sea clutter have been studied in time domain,frequency domain and polarization domain.Finally,a software system is designed for modeling,simulation,and characteristic analysis of sea clutter.Detailed work is summarized as follows:Firstly,with the fine description of dynamic sea surface model,the sea echo is simulated for different sea conditions.Specifically,the introduction is provided for the meaning of sea spectrum and several classical sea spectral models.To realize the fine depiction of the dynamic sea surface under different sea conditions,one mainstream method is used to model sea surface space geometry.Based on the scattering contribution of the surface-element theory,the generated physical sea surface is divided into several facet elements.And the two-scale model is used to calculate the scattering contribution dominated by large-scale and small-scale roughness,respectively.To be specific,the former is calculated with the Kirchhoff Approximation method,and the latter with the small perturbation method.Then the backscattering coefficients can be obtained for each surface element.Based on the principle of echo generation,the simulation of sea surface echo is completed.Secondly,characteristics of sea clutter have been studied,including the amplitude distribution and power spectrum,for target detection based on energy difference between target and clutter.The detailed introduction is provided for common amplitude distribution models and relative parameter estimation methods.Besides,methods for estimating spectral width and central frequency of power spectrum are introduced.Based on the high-resolution simulated data,the effect of four factors on the amplitude and spectral characteristics are analyzed,including the wind speed,incident grazing,incident carrier frequency,and wind angle,Thirdly,for the detection of low speed weak target,the features used to differentiate target and clutter are studied.Specifically,the time-frequency features and polarimetric features are introduced.Besides,the commonly used methods for time-frequency analysis and polarization decomposition are provided.According to the difference between the sea clutter and the target,the highly discriminative features for effective target detection can be obtained.Finally,the construction of the designed software system is introduced for sea clutter simulation and characteristic analysis.To be specific,five main contents are provided,including the principles followed by the interface design,the requirement of software development,the key technology of software realization,the composition and function of each module,and operation instructions of the software.