【作者】 谢寅；

【导师】 李佳；

【作者基本信息】 北京邮电大学 ， 通信与信息系统， 2010， 硕士

【摘要】 临近空间是新兴的一个研究热点,在临近空间建立雷达系统平台是其中的重点。本文对临近空间SAR系统的构建、布站方式进行了详细的分析和论述,同时成像,运动补偿方面进行了一些理论研究以及仿真实现。主要工作和成果如下：1.提出了基于临近空间的SAR系统平台。指出雷达系统需要有高频率稳定度的本振基准频率,天线子系统须受到平台控制系统的实时监控；确立了数据处理＼传输系统进行预处理再下传的机制；平台控制系统需要与地面系统建立良好的通信机制,同时对雷达系统进行实时的控制。2.对临近空间SAR系统的单基站、双基站和分布式多基站布站方式进行了初步的分析。指出单基站SAR相比机载SAR抗干扰强；相比星载SAR发射功率小,分辨率高的优点；并提出可建立组网模式；临近空间双基站回波随距离的衰减小,作用距离远,抗截获功能好,但同步性要求高、运动补偿复杂,并分析了其多种配对方式的优缺点；分布式多基站SAR能获得更高质量的图像、对地面动目标检测也有很好的效果、适合干涉SAR成像。3.重点针对临近空间SAR的斜视模式进行了详细的研究,指出在斜视角下合成孔径长度须考虑其精确表达式。从SAR.回波信号本身出发进行详细的分析推导,确立了先去距离走动、距离压缩,采取NCS方式进行三次相位滤除、剩余距离徙动校正以及二次距离压缩,完成方位向压缩和方位平动相位校正的成像算法。4.详细研究了临近空间SAR斜视模式的运动误差。指出侧向误差在临近空间的主要形式是摆动误差,给出了斜视模式下航迹误差的恒定扰动速度和余弦扰动速度以及侧向摆动误差的误差容限；进行了误差补偿分析,指出航迹误差可采用雷达斜视角近似分析,侧向误差不能忽视瞬时斜视角的变化；最后给出了基于运动补偿的成像算法。更多还原

【Abstract】 Near-space is emerging as a research hotspot at present, to create the radar platform in Near-space is one of the focal points.Some analysis and discussion in details has been made about architecture and layout of Synthetic Aperture Radar(SAR), whiles some theoretical studies of imaging and motion compesation has been done and simulation has been achieved in this article.The main results and achievements are as below:1. The platform of SAR system based on Near-Space has been given. Pointed out that the radar systems need to have high frequency stability of the local oscillator reference frequency; the antenna subsystem is subject to the platform control system’s real-time monitoring; a mechanism that data has been processed before transmission data-processing and transmission system has been established; a good communication mechanism should be established between platform control system and ground system.2. A preliminary analysis about Single-Static Bistatic and Muti-Static SAR in Near-Space has been made. Point out that Single-Static SAR in Near-Space has stronger anti-jamming compared to Airborne SAR, smaller transmit power and higher resolution compared to Satellite SAR; and put forward a proposal to establish a network model. Bistatic SAR in Near-Space has small echo attenuation compared to Single-Static, and a far operating distance, excellent ability of interception resistance, but need high synchronization and has complex motion compensation.In addition, point out the merit and demerit of the model of Bistatic SAR. Distributed Multi-Static can get high quality SAR images, has excellent ability of GMIT, and suitable for IFSAR.3. Detailed studies has been made focus on squint SAR imaging in Near-Space, pointing out that exact expression of synthetic aperture length should be considered under forward-squint mode. Starting from the echo signal itself, a detailed analysis has been derived. Established the algorithm that Range walk removal and Range compression at first, subsequent cubic phase filtering, SRC and RCMC by using NCS, completing azimuth compression and residual phase compensation at last.4. Detailed studies has been made focus on forward-squint SAR motion error in Near-Space. Pointing out that swing error is the main form of lateral error. Expression of error margin has been given of cross track error including constant disturbance velocity and cosine disturbance velocity, as well as lateral error. Analysis of motion compensation has been made. Pointed out that can use constant squint angle instead of instantaneous squint angle of track error, but cannot of lateral error. Finally, a algorithm with motion compensation has been given.更多还原