机载雷达杂波抑制技术的研究

【作者】 王洁；

【导师】 陈祝明；

【作者基本信息】 电子科技大学 ， 信号与信息处理， 2006， 硕士

【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是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。传统的机载雷达地杂波抑制方法采用多普勒频域一维自适应滤波,即利用杂波和目标信号回波在多普勒频域上的差别对杂波进行抑制。频域一维滤波主要考虑主杂波的抑制。而且对于低速目标,目标和杂波多普勒频率非常接近,其杂波抑制能力严重下降。空时自适应处理利用机载雷达地杂波多普勒频率与地杂波空间位置的耦合性,根据目标和杂波在空间-多普勒频域二维空间分布上的差别对杂波进行抑制。但庞大的计算量限制了STAP在工程中的应用。本文对机载雷达杂波抑制技术进行研究,该研究对自适应滤波和谱估计的快速实时应用及工程研制具有重要意义。内容主要包括以下几个方面。首先分析总结了地物杂波频谱的组成特性,系统地阐述了机载雷达杂波抑制的基本理论及其发展动态。重点讨论了基于谱宽估计的杂波抑制方法。分别采用计算机仿真回波数据和一组真实的飞行数据,对该方法和AMTI两种运动杂波抑制技术进行了比较和分析,为工程实现做理论准备。完成了基于谱宽估计的杂波抑制方法的实现,通过对多片数字信号处理器ADSP21160编程实现信号杂波抑制和动目标检测的功能,该模块具有结构简单、系统稳定、能适应灵活信号处理的优点,并且已经成功应用于某机载相控阵雷达,在工程实践中取得很好的效果。在不改变现有雷达体制的条件下,通过改变雷达发射信号的形式及信号的处理算法,提高雷达的性能,本文对Chirp子脉冲频率步进雷达信号进行研究,讨论了信号参数的设置,证明了该信号与单个Chirp子脉冲相比有更高的输入信杂比。更多还原

【Abstract】 Radar equipped in an airplane 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 defence. 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 complicatied clutter environment. The complexities of clutter back ground mainly embody in large amplitude interference of ground clutter, 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. Conventional airborne radar clutter suppression techniques utilize the diffrernce in Doppler frequency domain between clutter and target returns to suppress clutter. Doppler frequency domain one-dimension adaptive filtering, which usually used in main lobe clutter suppression. For slow targets whose Doppler frequencies fall into clutter Doppler band, the performance of frequency domain one-dimension filtering is seriously degraded. In an airborne radar, there is interdependence between the clutter Doppler frequency and spatial position. Space-time adaptive processing(STAP) utilizes this interdependence to suppress clutter and get perfect main-lobe and side-lobe clutter suppression. But STAP is too complex to be realized.This dissertation focuses on studying adaptive clutter suppression of airborne Radar. It not only gives impetus to the application of adaptive filtering and spectral estimation but also have important significance to project development. Main content can be concluded as following.The characteristics of the ground clutter are analyzed and presented. The development and the theories of clutter suppression of airborne Radar are desicribed systematically.The performance of adaptive spectral estimation is analyzed. The AMTI algorithm and adaptive spectral estimation algorithm are compared through the results of computer simulations and a pragmatic radar data.更多还原