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Advanced High Resolution Methods for Radar Imaging and Micro-Doppler Signature Extraction

用于雷达成像和微多普勒特征提取的先进高分辨率方法

基本信息

批准号：
EP/H012877/1
负责人：
John Soraghan
金额：
$ 10.92万
依托单位：
University of Strathclyde
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FH012877%2F1
关键词：
Advanced Resolution Methods Radar Imaging

项目摘要

Imaging radars are airborne or spaceborne radars which generate a reflectivity map of an illuminated area through transmission and reception of electromagnetic energy. Among many types of microwave sensors, special attention has been paid in the past to Synthetic Aperture Radar (SAR) because of its high spatial resolution, day or night all weather operational capabilities. With its fine two-dimensional resolution capability SAR has evolved to satisfy a variety of applications for both civilian and military users. These applications centre on target imaging and terrain mapping. A target is a specific object of interest that the radar illuminates. The typical target is man-made and consists of multiple scattering centres. An imaging radar system must distinguish between single and multiple scatters located in close proximity. Resolution is, nominally, the minimum distance needed between adjacent scatters to separate them in the image. Fine resolution provides the capability to image a complex object or scene as a number of separate scattering centres. This type of image provides detailed information to detect, characterize, and identify specific objects of interest. Because of the importance of object identification in military applications, much development effort has been directed at improving radar resolution. Military SAR applications include intelligence gathering, battlefield reconnaissance, and weapons guidance. Civilian applications include topographic mapping, oil spill monitoring, sea ice characterization and tracking, agricultural classification and assessment, lands use monitoring, and planetary or celestial investigations. Normally imaging radars provide a two-dimensional representation of a scatterer in the illuminated volume with no resolution or positioning of scatterer in the third dimension. Generally, we speak of monstatic (the transmitter and receiver are co-located) radar resolution in the range and cross-range or azimuth directions. Bistatic radars, where the transmitter and receiver are positioned in different physical positions have several operational advantages. In particular such bistatic systems help to increased receiver survivability while minimising receiver cost. Furthermore when one or both of the platforms are manoeuvring in an non linear planar path allows the resolution to be computed in the 3rd dimension thus facilitating the acquisition of target height information as well range and cross range resolution.When a radar interrogates a moving target it is traditional to exploit the target's Doppler for identification and characterisation. If the target possesses additional rotational, vibration or other internal motions then these induce additional spectral components separate from the main Doppler. These are termed microdoppler components and reside as additional sidebands around the main Doppler. A human walking or running will exhibit microdopplers due to swinging arms and leg movements. A military tank will exhibit microdopplers due to the wheel tracks while a helicopter and engine target will exhibit key microdoppler components. The use of time frequency signal representation such as the short time Fourier transform and wavelet analysis has been used to examine these microdopplers in the past. Good quality microdoppler signatures are important in new automatic target identification and recognition systems. Quality is directly related to the extracted microdoppler resolution extracted.The aim of this work is to explore new signal processing techniques which can be used to improve the resolution of the imaging radars algorithms and microdoppler signature extraction. The work will derive new mathematical relationships for bistatic spotlight SAR image formation and microdoppler signature extraction based on the Fractional Fourier transform and empirical mode decomposition. An FrFT compute engine will be realised and the algorithms will be tested on simulated and real data.

成像雷达是机载或星载雷达，通过发射和接收电磁能量来生成照明区域的反射率图。在众多类型的微波传感器中，合成孔径雷达(SAR)因其高空间分辨率、全天候全天候作战能力而备受关注。凭借其良好的二维分辨能力，合成孔径雷达已经发展到能够满足民用和军用用户的各种应用。这些应用集中在目标成像和地形测绘上。目标是雷达照明的特定感兴趣的对象。典型的目标是人造的，由多个散射中心组成。成像雷达系统必须区分距离很近的单个和多个散射体。名义上，分辨率是相邻散射体之间在图像中分隔它们所需的最小距离。高分辨率提供了将复杂对象或场景成像为多个独立散射中心的能力。这种类型的图像提供了检测、表征和识别特定感兴趣对象的详细信息。由于目标识别在军事应用中的重要性，人们一直致力于提高雷达的分辨率。军事SAR的应用包括情报收集、战场侦察和武器制导。民用应用包括地形测绘、溢油监测、海冰特征和跟踪、农业分类和评估、土地利用监测以及行星或天文调查。通常，成像雷达在照明体中提供散射体的二维表示，而在第三维中没有散射体的分辨率或定位。通常，我们说的是单基地(发射机和接收机位于同一位置)雷达在距离和跨距离或方位方向上的分辨率。发射机和接收机位于不同物理位置的双基地雷达有几个操作优势。具体地说，这种双基地系统有助于提高接收机的生存能力，同时最小化接收机成本。此外，当一个或两个平台在非线性平面路径上机动时，可以在三维空间计算分辨率，从而便于获取目标高度信息以及距离和横向距离分辨率。当雷达询问运动目标时，传统上利用目标的多普勒来识别和表征目标。如果目标具有额外的旋转、振动或其他内部运动，则这些运动会引起与主多普勒波分离的额外频谱分量。这些被称为微多普勒组件，驻留在主多普勒周围的附加边带。人类行走或奔跑时，由于手臂和腿的摆动，会出现微多普勒现象。军用坦克将因轮轨而展示微多普勒，而直升机和引擎目标将展示关键的微多普勒组件。过去，人们利用短时傅里叶变换和小波分析等时频信号表示法来检测这些微多普勒器。在新的自动目标识别和识别系统中，高质量的微多普勒特征是重要的。提取出的微多普勒信号的分辨率直接关系到提取的质量。本工作的目的是探索新的信号处理技术，用于提高成像雷达算法的分辨率和微多普勒信号的提取。该工作将为基于分数阶傅里叶变换和经验模式分解的双基地聚束SAR成像和微多普勒特征提取推导出新的数学关系。将实现FrFT计算引擎，并在模拟和真实数据上对算法进行测试。