非合作星地双基地SAR成像算法及相关技术研究

【作者】 何煦；

【导师】 田忠；

【作者基本信息】 电子科技大学 ， 电路与系统， 2008， 硕士

【摘要】 双基地合成孔径雷达(SAR)是一种将接收系统和发射系统分置于不同平台上的新型SAR体制。与常规的单基地SAR相比,双基地SAR具有获取目标信息丰富、隐蔽性高和抗干扰性强等优点,在军事和国民经济的诸多领域均有良好的应用前景。近年来,双基地SAR已成为国际SAR技术研究的一个新热点。本文首先分析了任意飞行模式下的双基地SAR系统,建立了几何模型和回波信号模型,分析了其多普勒特性、分辨率特性和双基地雷达方程等,得出双基地SAR回波信号特性与收发布局模式密切相关。然后重点研究了非合作星地双基地SAR模式,并建立了该模式下的几何模型和回波信号模型,分析了其多普勒特性、分辨率特性和测绘带特点等。较深入的研究了双基地SAR成像算法。分析并给出了适合非合作星地双基地SAR模式的双基地RD算法和双基地BP算法。通过对点目标及面目标仿真数据成像处理,验证了两种算法的有效性和适用性。最后对两种算法的成像效果和运算量进行了分析和比较。多普勒参数估计方法是RD算法的关键技术,也是进行运动补偿的必要步骤。本文首先对几种典型的相位误差进行了分析,通过仿真给出了它们对成像带来的影响。接着分析研究了四种多普勒参数估计法,通过仿真验证了它们在非合作星地双基地SAR模式下的有效性和适用性。并对各种算法的估计精度进行了比较。仿真结果表明:在多普勒中心频率的估计中,图像域能量均衡法的估计精度要高于回波域能量均衡法;在多普勒调频斜率的估计中,相位梯度法的估计精度要高于子视图法。分析研究了双基地同步误差对成像的影响。对存在收、发系统照射同步误差、时间同步误差和频率同步误差的三种情况分别进行了仿真研究,给出了它们对成像处理带来的影响。本文最后介绍了一款适用于星地双基地SAR回波数据采集的接收机系统。给出了该接收机系统的组成和工作原理。介绍了接收机室内测试过程,并对采集到的数据进行了初步成像处理,验证了接收机系统的有效性。更多还原

【Abstract】 Bistatic Synthetic Aperture Radar(BiSAR) is a newly SAR system that operates with separated transmitter and receiver on different platforms. This system has several advantages like obtain rich information, security and anti-jamy compared to normal SAR. It will play a significant role in military as well as civil applications in the future.The general BiSAR is introduced firstly, the geometry and signal models of BiSAR are built. The properties of Doppler,resolutions and Radar Equation are analyzed. The conclusion,the digital processing of Bistatic SAR is related to the geometry models. The thesis place special emphases on researching Non-Cooperate Space-Ground BiSAR, include the geometry and signal models, the properties of Doppler, resolutions and the character of the irradiation-band.The imaging algorithm of Bistatic SAR is studied deeply. The RD algorithm and BP algorithm that fit for the model of Non-Cooperate Bistatic SAR are given. In order to validate the validity and applicability of algorithms in the model, the echo data of point target and scene target are processed by two algorithms respectively. Imaging quality and computation load of two algorithms are compared at last.Phase errors are given first, and then theoretical analysis,simulation result show influence caused by several kinds of typical phase errors. In order to validate the validity and applicability of algorithms in the Non-Cooperate model, the echo data with errors is estimated by algorithms respectively.The influence for image caused by Synchronic Error has been discussed and studied. The influence is simulated by the error of irradiation synchronization, time synchronization and frequency synchronization.A Receiver system fit for receiving Space-Ground BiSAR echo signal is introduced. Principle and components are given. Result of lab experiment is presented. The echo received by receiver is processed elementarily, the result proved the correctness of the echoed data and the receiver system can work well.更多还原