【作者】 焦丽；

【导师】 常建平； 朱根才；

【作者基本信息】 南京航空航天大学 ， 信号与信息处理， 2008， 硕士

【摘要】 杂波研究经过几十年的发展,仍然是雷达技术的热点。机载PD雷达地杂波强度大、杂波谱分布广,特别在下视状态下在所有的距离上都成为目标检测的背景,因此,机载PD雷达地杂波的研究和计算已经成为机载雷达最基本和最关键的研究课题之一。本文从机载下视雷达地杂波散射机理出发,结合机载下视雷达地杂波的特殊性,首先概括了机载下视雷达常用的杂波信号的特性即空间相关性和时间相关性,讨论了几种常用的相关杂波的模拟方法,做出了有效的模拟结果。网格划分法是机载雷达地杂波分析和计算时常用的分析方法,本文通过对机载雷达地杂波的几种网格划分方法的分析发现,杂波网格单元大小不一、形状各异,有可能超过了雷达的分辨率,因此,本文提出了地面杂波具有扩展目标的性质的观点。而角闪烁是扩展目标最重要的性质,于是本文对由扩展目标的角闪烁性质引起的杂波幅度起伏和相位分布进行了数字仿真;为了提高仿真精度,本文提出了模拟具有特定频谱特性的扩展目标算法,并对叠加频谱特性前后的序列进行了分析比较。基于前面对地面杂波特性的讨论和对机载下视雷达地面后向散射系数模型的研究,在充分考虑地面杂波起伏特性的情况下,本文提出了一种基于RCS起伏模型的机载下视雷达地杂波功率谱算法,并在Matlab平台上仿真实现,仿真结果与理论分析正好吻合,提高了杂波模拟的逼真度。更多还原

【Abstract】 Radar clutter is still a hot topic after decades of study. Pulse-Doppler radar clutter is quite strong with widely distributed power spectrum. Especially when the radar is in the“look down mode”, it is the background of target detection in all range gates. So calculation and study of airborne radar clutter has become a basic and critical problem in the field of clutter research.After analyzing the surface clutter scattering mechanism of airborne radar, combining with the clutter characteristic of airborne radar in a look down mode, the characteristics of clutter signal including special correlation and time correlation, is summarized in the beginning. Then discussions are presented on several common algorthms for clutter simulation and simulation results are shown after that. Grid partition method is a common used method in analyzing and calculating ground clutter. In this paper, several ways of grid partition are summarized. Considering that some cells might exceed radar resolution because of their non-uniform sizes and various shapes, an idea that ground clutter of airborne radar can be treated as extended target is proposed. Because angular glint is the main characteristic of the extended target, so in this paper, amplitude fluctuation of ground clutter caused by this characteristic is simulated. In order to improve accuracy of the simulation, corresponding algorithm with special frequency-domain characteristic is proposed, and further simulation is made for comparison. Based on former discussions over characteristics of ground clutter and study on backscattering coefficient of airborne radar ground clutter, an algorithm, which is used to calculate power spectrum of ground clutter of airborne radar based on fluctuated RCS, is proposed. In this paper, all simulations are carried on Matlab platform and results accord well with theoretical analysis. So effectiveness of the algorithms is identified and simulation fidelity improved.更多还原