空间立体阵星载SAR杂波抑制技术研究
发布时间：2018-09-07 13:06
【摘要】：合成孔径雷达(Synthetic Aperture Radar,SAR)是二战之后新兴的一种全天时全天候的天基雷达,主要应用于机载和星载平台,星载SAR系统主要由若干个卫星雷达按照一定的空间构型组成。与常规SAR系统相比,星载SAR系统具有空间自由度高、系统复杂度低、工作模式多样等优势,应用领域十分广泛。实际的星载SAR场景中杂波表现出距离非平稳特性,同时在一个相干积累间隔(Coherent Processing Intervals,CPI)内目标与SAR系统的距离走动超过了一个距离单元(称之为长CPI模式)。据此本课题在建立立体阵SAR目标和杂波回波信号模型后,研究运动目标和杂波的频谱特性,在此基础上研究距离非平稳杂波抑制算法和长CPI模式下的杂波抑制技术。本文主要的研究内容和成果如下:(1)研究空间立体阵星载SAR系统下目标和杂波的回波信号模型、动目标模型,讨论目标运动对于距离徙动、多普勒频率以及多普勒调频率的影响。分析杂波的产生机理以及回波信号中的杂波来源,讨论不同分布的杂波的概率密度。得出了K分布杂波能够有效地模拟其它多种杂波的结论,利用球不变随机过程法生成K分布杂波用以抑制算法。(2)在距离非平稳杂波背景下研究空间立体阵星载SAR系统的空时自适应处理(Space Time Adaptive Processing,STAP)算法以及降维方法。首先分析杂波的空时特性,研究常规STAP算法对于非平稳杂波进行抑制的有效性。研究距离向非平稳杂波的频谱特性以及对回波信号的影响,发现非平稳杂波的频谱特性与俯仰向信息有关。根据立体阵系统雷达构型的特点,将常规STAP算法扩展到空(方位向)—时—空(俯仰向)三维STAP算法。利用回波信号中增加的目标和杂波的俯仰维度信息,实现对非平稳杂波的抑制,仿真结果表明三维STAP算法对距离非平稳杂波有较好的抑制效果。研究局域联合处理(Joint Domain Localized-JDL)方法和先时后空自适应(3DT-STAP)方法在降低算法运算量和保证输出信噪比(Signal Interference Noise Ratio,SINR)的性能。(3)研究长CPI和短CPI模式SAR系统信号频谱之间存在的差异,研究杂波的频谱特性后发现常规STAP技术已经不能继续适用,将全时空信号投影在频率—多普勒域子空间内,根据子空间内杂波的独立性对全空时信号进行降维处理,在子空间内部进行局部STAP处理,将全部子空间的处理结果利用静止目标斜视成像算法进行相干积累,最后利用仿真实验验证局部STAP处理和相干积累结果的有效性,分析CPI的大小以及卫星基线的长短对于STAP处理结果的影响。
[Abstract]:Synthetic Aperture Radar (Synthetic Aperture Radar,SAR) is a new type of space-based radar which is developed after World War II. It is mainly used in airborne and spaceborne platforms. Spaceborne SAR system is mainly composed of several satellite radars in a certain space configuration. Compared with conventional SAR system, spaceborne SAR system has many advantages, such as high degree of freedom in space, low system complexity, various working modes, and so on. In the actual spaceborne SAR scene, the clutter shows a non-stationary range, and the range walk between the target and the SAR system in a coherent accumulation interval (Coherent Processing Intervals,CPI) exceeds a range unit (known as the long CPI mode). Based on this, the spectral characteristics of moving targets and clutter are studied after the establishment of stereo array SAR target and clutter echo signal model, and the range nonstationary clutter suppression algorithm and the clutter suppression technique under long CPI mode are studied. The main contents and achievements of this paper are as follows: (1) the echo signal model and moving target model of target and clutter in space-borne spaceborne SAR system are studied, and the effects of target motion on range migration, Doppler frequency and Doppler modulation frequency are discussed. The generation mechanism of clutter and the source of clutter in echo signal are analyzed, and the probability density of clutter with different distribution is discussed. It is concluded that K-distributed clutter can effectively simulate other kinds of clutter. The spherical invariant random process method is used to generate K-distributed clutter to suppress the algorithm. (2) Space-time adaptive processing (Space Time Adaptive Processing,STAP) algorithm and dimensionality reduction method for space-time adaptive processing of spaceborne SAR systems with space stereoscopic array are studied in the background of non-stationary clutter. Firstly, the space-time characteristic of clutter is analyzed, and the effectiveness of conventional STAP algorithm to suppress non-stationary clutter is studied. The spectral characteristics of the range nonstationary clutter and its influence on the echo signal are studied. It is found that the spectrum characteristics of the non-stationary clutter are related to the pitching information. According to the characteristics of radar configuration of stereo array system, the conventional STAP algorithm is extended to three dimensional (azimuth)-time-air (pitch) STAP algorithm. The suppression of non-stationary clutter is realized by using the additional target information and pitch dimension information of clutter in echo signal. The simulation results show that 3D STAP algorithm can suppress the non-stationary clutter in distance. The performance of the local joint processing (Joint Domain Localized-JDL) method and the first time posterior space adaptive (3DT-STAP) method in reducing the computational complexity and ensuring the output signal-to-noise ratio (Signal Interference Noise Ratio,SINR) is studied. (3) the differences between the signal spectrum of the SAR system with long CPI and short CPI mode are studied. After studying the spectral characteristics of clutter, it is found that the conventional STAP technique is no longer applicable. The whole space-time signal is projected in the frequency-Doppler subspace, and the dimension reduction of the space-time signal is carried out according to the independence of the clutter in the subspace. The local STAP processing is carried out inside the subspace, and the processing results of all the subspaces are integrated by the static target squint imaging algorithm. Finally, the effectiveness of the local STAP processing and the coherent integration result is verified by the simulation experiment. The influence of the size of CPI and the length of satellite baseline on the processing results of STAP is analyzed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN957.51
本文编号：2228347
[Abstract]:Synthetic Aperture Radar (Synthetic Aperture Radar,SAR) is a new type of space-based radar which is developed after World War II. It is mainly used in airborne and spaceborne platforms. Spaceborne SAR system is mainly composed of several satellite radars in a certain space configuration. Compared with conventional SAR system, spaceborne SAR system has many advantages, such as high degree of freedom in space, low system complexity, various working modes, and so on. In the actual spaceborne SAR scene, the clutter shows a non-stationary range, and the range walk between the target and the SAR system in a coherent accumulation interval (Coherent Processing Intervals,CPI) exceeds a range unit (known as the long CPI mode). Based on this, the spectral characteristics of moving targets and clutter are studied after the establishment of stereo array SAR target and clutter echo signal model, and the range nonstationary clutter suppression algorithm and the clutter suppression technique under long CPI mode are studied. The main contents and achievements of this paper are as follows: (1) the echo signal model and moving target model of target and clutter in space-borne spaceborne SAR system are studied, and the effects of target motion on range migration, Doppler frequency and Doppler modulation frequency are discussed. The generation mechanism of clutter and the source of clutter in echo signal are analyzed, and the probability density of clutter with different distribution is discussed. It is concluded that K-distributed clutter can effectively simulate other kinds of clutter. The spherical invariant random process method is used to generate K-distributed clutter to suppress the algorithm. (2) Space-time adaptive processing (Space Time Adaptive Processing,STAP) algorithm and dimensionality reduction method for space-time adaptive processing of spaceborne SAR systems with space stereoscopic array are studied in the background of non-stationary clutter. Firstly, the space-time characteristic of clutter is analyzed, and the effectiveness of conventional STAP algorithm to suppress non-stationary clutter is studied. The spectral characteristics of the range nonstationary clutter and its influence on the echo signal are studied. It is found that the spectrum characteristics of the non-stationary clutter are related to the pitching information. According to the characteristics of radar configuration of stereo array system, the conventional STAP algorithm is extended to three dimensional (azimuth)-time-air (pitch) STAP algorithm. The suppression of non-stationary clutter is realized by using the additional target information and pitch dimension information of clutter in echo signal. The simulation results show that 3D STAP algorithm can suppress the non-stationary clutter in distance. The performance of the local joint processing (Joint Domain Localized-JDL) method and the first time posterior space adaptive (3DT-STAP) method in reducing the computational complexity and ensuring the output signal-to-noise ratio (Signal Interference Noise Ratio,SINR) is studied. (3) the differences between the signal spectrum of the SAR system with long CPI and short CPI mode are studied. After studying the spectral characteristics of clutter, it is found that the conventional STAP technique is no longer applicable. The whole space-time signal is projected in the frequency-Doppler subspace, and the dimension reduction of the space-time signal is carried out according to the independence of the clutter in the subspace. The local STAP processing is carried out inside the subspace, and the processing results of all the subspaces are integrated by the static target squint imaging algorithm. Finally, the effectiveness of the local STAP processing and the coherent integration result is verified by the simulation experiment. The influence of the size of CPI and the length of satellite baseline on the processing results of STAP is analyzed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN957.51
【参考文献】
相关期刊论文 前10条
1 Guo Jiao;Xu Youshuan;Fu Longsheng;;An extended chirp scaling algorithm for spaceborne sliding spotlight synthetic aperture radar imaging[J];Chinese Journal of Aeronautics;2014年04期
2 ;Efficient DPCA SAR imaging with fast iterative spectrum reconstruction method[J];Science China(Information Sciences);2012年08期
3 邓云凯;赵凤军;王宇;;星载SAR技术的发展趋势及应用浅析[J];雷达学报;2012年01期
4 常玉林;周红;黄晓涛;周智敏;;多通道SAR频率多普勒域宽带长CPI STAP方法[J];电子学报;2011年06期
5 徐青;廖桂生;张娟;杨志伟;;SAR-GMTI构型下分布式小卫星误差估计方法[J];电子学报;2011年04期
6 和洁;冯大政;吕晖;向聪;;机载雷达三维空时自适应相关域降维算法[J];系统工程与电子技术;2011年02期
7 段克清;谢文冲;高飞;王永良;;基于杂波自由度的STAR模型参数估计方法[J];信号处理;2009年11期
8 余慧;闫鸿慧;王岩飞;;分布式卫星ATI-SAR性能分析与基线估计[J];电子与信息学报;2009年06期
9 高飞;谢文冲;王永良;;非均匀杂波环境3D-STAP方法研究[J];电子学报;2009年04期
10 杨凤凤;梁甸农;张永胜;;分布式星载SAR-GMTI时频同步误差去相关分析[J];信号处理;2008年04期
相关博士学位论文 前1条
1 李晨雷;分布式SAR动目标成像关键技术研究[D];哈尔滨工业大学;2015年
，本文编号：2228347
本文链接：https://www.wllwen.com/kejilunwen/xinxigongchenglunwen/2228347.html
