Research On Characteristic And Image Reconstruction Of Radar Clutter By Using Real SAR Image

In the process of target detection and identification in complex environment, the echo signals received by the radar include not only the information about the target, but also the scattering echo from ground environment, which is known as ground clutter. The complex and variable radar target and environment, determines the ground clutter has great influence in the radar’s target detection ability. Specific clutter character must be analyzed and studied for promoting the accuracy in the object identified speed, and then the clutter could be suppressed. Statistics properties and spatial correlation of ground clutters base on the actual measurement farmland image and concrete image are analyzed with the incorporation of application background in practice. The main work of the paper is organized as following:1. The first section summarized the present status and development trend of domestic and overseas research of ground and sea clutter from three sides respectively. First one is the experimental measurement; second one is the backscatter model which base on the clutter reflectivity mechanism; another one is clutter simulation based on statistical.2. The second section introduces the radar cross section and the condition which could affects the radar cross section. Several numeric methods and analytical methods in electromagnetic scattering coefficient calculation are discussed. Also, we introduce four kinds of statistical distribution models which are Rayleigh, Lognormal, Weibull, and K distribution and discuss the variation of four kinds of models with distribution parameters. Finally, the estimation methods of model parameters are introduced.3. The data obtained from the measured image are analyzed. And the parameter estimation algorithm is introduced to get the distributed parameter of the statistical models. Besides, the obtained probability density of various empirical models matches well with the distribution probability of original image. Introduce two frequently used methods of test of goodness of f it, K-S test and chi-square test method. Use K-S test method to test fitting, and show the lognormal distribution model is the optimal model. Get the clutter data’s correlation from the image data.4. Two kinds of typical clutter simulation methods: Zero Memory Nonlinearity(ZMNL) and Spherically Invariant Random Process(SIRP), both the advantages and disadvantages of each method are analyzed. Also, the way to get white Gaussian noise and the generation method of filter in the simulation process is presented. Mainly provides the information about how ZMNL method dealing with Log-normal distribution and compare the simulated probability density distribution with original image of farmland clutter and cement clutter. Echo data of clutter by ZMNL is given.5. The theory of synthetic Aperture Radar(SAR) is recommended with two kinds of typical imaging algorithm: LFM algorithm and R-D algorithm. Clutter imaging simulation was done with the echo data using R-D algorithm, which gives verification to the reliability of R-D imaging algorithm and the feasibility of the sort of clutter reconstruction algorithm.