毕业设计(论文)-基于Matlab的机载雷达的地杂波仿真实现及抑制技术

机载雷达的地杂波仿真实现及抑制技术

摘要

机载雷达由于架设在运动的高空平台上，具有探测距离远、覆盖范围大、机动灵活等特点，应用范围相当广泛，可以执行战场侦察、预警等任务。在海湾战争、伊拉克战争中起到关键作用，在现代战争中越来越不可缺少，因此近年来受到广泛重视。但由于机载雷达的应用面临非常复杂的杂波环境，杂波功率很强，载机的平台运动效应使杂波谱展宽。此外，飞机运动时，杂波背景的特性会随时间变化。因此，有效地抑制这种时间非平稳和空间非平均的杂波干扰时雷达系统有效完成地面目标和低空飞行目标检测必须解决的首要问题。

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。

本文从机载下视雷达地杂波散射机理出发，结合机载下视雷达杂波的特殊性，首先概括了机载雷达常用的杂波信号的特性即空间相关性和时间相干性，讨论了几种常用的相关杂波的模拟方法，做出了有效地模拟结果，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。并对机载雷达波抑制技术进行研究，分析总结了地物杂波频谱的组成特性，系统的阐述了机载雷达杂波抑制的基本理论及其发展动态。重点讨论了AMTI杂波抑制技术并给出仿真结果。

关键词：机载雷达；地杂波；杂波抑制；AMTI

Ground Clutter Simulation and Suppression

For Airborne Radar

ABSTRACT

Radar equipped in an airborne has many merits such as seeing things beyond the visibility of Ground-based radar, flexibility in application. It plays an important part and is widely used in national defense. Its value of application has been testified in the war of Gulf and Iraq. So it attracts great attention of many nations in the world. But airborne radar will face highly complicated clutter environment. The complexities of clutter back ground mainly embody in large amplitude interference of ground clutter and clutter spectrum spread caused by platform movement effect. And the characteristics of the ground clutter change as well as time change. The key to the settlement of the question of effective detection of ground and low air targets lies in adaptive of effective clutter suppression in airborne Radar.

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.

Firstly, the surface clutter scattering mechanism of airborne radar is analyzed, and the characteristics of clutter including special correlation and time correlation are summarized for airborne radar in a look down mode. Then all simulations are carried on Matlab platform and the results accord well with theoretical analysis. This dissertation focuses on studying adaptive clutter suppression of airborne Radar. The characteristics of the ground clutter are analyzed and presented. The development and the theories of clutter suppression of airborne Radar are described systematically.

Key Words: airborne radar; ground clutter; clutter suppression; AMTI

目录

第一章绪论 (1)

课题背景与研究意义 (1)

杂波仿真技术的发展和研究现状 (1)

主要研究内容 (2)

第二章机载雷达地杂波的特性分析及仿真原理 (4)

机载雷达地杂波回波谱分析 (5)

2.1.1 主瓣杂波频谱 (5)

主瓣杂波频谱分析 (7)

机载雷达地杂波仿真原理 (8)

基本雷达方程 (8)

杂波信号的特性 (9)

第三章机载雷达地杂波仿真实现 (12)

高斯分布统计模型 (12)

非高斯分布统计模型 (14)

对数正态（Lognormal）分布 (14)

韦布尔（Weibull）分布 (16)

3.2.3 K分布和gamma分布 (18)

3.3 机载雷达杂波特性 (21)

机载雷达不确定场地地面杂波仿真 (22)

模型假设及输入参数 (22)

散射单元的划分 (23)

3.4.3 杂波散射单元回波信号 (25)

3.4.5 回波叠加 (27)

3.4.6 机载雷达杂波仿真结果 (28)

第四章机载雷达地杂波抑制技术 (30)

4.1 动目标显示（MTI） (30)

4.2 单延迟线对消器 (31)

4.3 双延迟线对消器 (33)

4.4 反馈延迟线对消器（递归滤波器） (35)

第五章结论与展望 (37)

参考文献 (39)

附录A (41)