Superresolution Method Of Airborne Radar For Sea-surface Target

Super-resolution imaging technology of airborne radar in the forward-looking area is urgently needed in applications such as naval battlefield situation awareness,fighter aircraft blind landing navigation,and surveillance radar.Although the traditional methods can realize azimuth high-resolution radar imaging,there is a main drawback that the forward looking has imaging blind area.The traditional real aperture scanning radar can realize the imaging of the forward-looking area,and has the strengths of clear model,higher compatibility,lower cost and wider applicability.However,the azimuth resolution of real aperture scanning radar for forward-looking sea targets is low.In order to improve the super-resolution capability to sea targets of airborne radars,and use real aperture radar system,this thesis proposes a deconvolutional angle super-resolution approach based on the maximum posterior probability.The proposed method breaks through the inherent limitation of the antenna aperture of the real aperture scanning radar,and thus can achieve the imaging target.The main contents are as follows:1.Under the imaging system of the real aperture scanning radar,according to the geometric configuration of the radar system scanning imaging,a real aperture scanning radar signal model is presented.Through echo signal preprocessing techniques such as motion compensation,the azimuth echo is characterized as a convolution model.2.Under the background of Rayleigh sea clutter,we have presented an imaging method.The objective function is constructed based on the maximum a posteriori criterion,and the prior information of the target in the deconvolution is described by the lognormal distribution function.The Picard algorithm is used to obtain the solution of the target scattering coefficient.The proposed method can improve the azimuth resolution and sea clutter suppression capability of real aperture scanning radar.3.Based on the background of Weibull clutter,an angular super-resolution method of sea-surface target in forward-looking imaging is proposed.Laplace distribution is used to represent the target,and the objective function is derived based on the maximum a posteriori criterion.The Newton-Raphson method is introduced to solve the function.The proposed method can get better performance,and improve the universality of the methods based on the maximum a posterior probability.The above-mentioned radar imaging model and super-resolution methods have been verified through computer simulation and practical data processing.The results indicate that the proposed approaches can deal with clutter amplification and low azimuth resolution of real aperture scanning radar during the super-resolution process of sea targets.