【作者】 马喜乐；

【导师】 董臻；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2010， 硕士

【摘要】 现代对地观测任务对星载合成孔径雷达(SAR)的高分辨率宽测绘带(HRWS)成像能力提出了越来越高的要求,而传统SAR模式如条带式(Stripmap)、扫描式(ScanSAR)和聚束式(Spotlight)等均不能同时满足高分辨和宽测绘带的要求。偏置相位中心方位多波束(DPCMAB)模式为一发多收模式,能够解决高分辨率和宽测绘带要求之间的矛盾从而实现连续高分大测绘带成像。SAR距离分辨率依赖于信号带宽,而目前星载SAR系统在超大带宽(如X波段2GHz带宽)信号的产生、接收等方面存在很大的困难。步进调频信号带宽合成技术通过多子带信号的数据融合实现距离向超高分辨,显著降低了系统实现超高距离分辨率的难度。将偏置相位中心方位多波束和子带步进调频信号同时发射的信号收发体制相结合,形成多发多收(MIMO)SAR,可以实现二维超高分辨率的宽测绘带星载SAR系统,本文就这种新体制SAR的相关问题展开研究。第二章阐述了DPCMAB原理与方法,对关键误差进行了建模、仿真与分析,对基于特显点的阵列误差估计方法和联合迭代自校正方法进行了分析、比较。第三章分析了DPCMAB系统参数对信号重构性能的影响,提出了基于有源相控阵雷达灵活波束形成能力的自适应阵列配置方法以优化系统性能。第四章研究了子带并发体制的原理以及信号处理方法,分析了子带信号的非完全正交对成像带来的影响,针对虚像问题提出利用正负调频步进频信号对虚像的峰值电平进行抑制,提出了基于特显点的误差补偿方法。第五章阐述了基于DPCMAB与子带并发技术的MIMO HRWS SAR体制,基于这一体制开展了回波模拟、数据融合以及成像处理研究,验证了这种新体制SAR的二维高分辨成像能力。更多还原

【Abstract】 Modern earth observation missions put forward higher and higher request on the capability of high resolution and wide swath (HRWS) imaging for spaceborne synthetic aperture radar (SAR). Conventional SAR systems such as Stripmap SAR, ScanSAR and Spotlight SAR systems are not capable of fulfilling the increasing demands for improved spatial resolution and wider swath coverage. As a single-output multiple-input SAR system, displaced phase centers multiple-azimuth-beam (DPCMAB) system solving the inherent conflict between azimuth resolution and swath width, thus realizes continuous earth observation with excellent HRWS imaging capability. Range resolution depends on signal bandwidth, but spaceborne SAR systems still encounter great difficulties in generation, transmitting and other aspects of signal with so wide bandwidth. Synthetic bandwidth technology of stepped chirp signal achieves high range resolution by fusing the sub-band signal with smaller bandwidth, can reduce system burden remarkably.Forming a multiple-input multiple-output (MIMO) SAR system by combining DPCMAB and concurrent-sub-band of stepped chirp signal, wide swath as well as high resolution on the two dimension can be achieved simultaneously. This thesis focuses on such problems of this system as systematical principal, performance analysis, signal processing ,error analysis and so on. The principal and signal processing theory of DPCMAB system is interpreted in Chapter 2, after simulation and analysis to critical errors, dominant scatter based algorithm and joint iterative self-tuning algorithm used to estimation of array errors are simulated and analyzed. Influence of systematic parameters on signal reconstruction performance is analyzed in Chapter 3, based on the flexible beam forming capability of active phased array antenna, adaptive array configuration approach used to optimizing signal reconstruction performance is expatiated. The principal and signal processing theory of concurrent-sub-band system is studied in chapter 4, the influence of incomplete orthodoxy of sub-band signal is analyzed, up and down chirp modulated stepped chirp signal is used to suppress the peak level of the unwanted virtual image and it’s validity and limitation is presented,dominant scatter based error compensation approach is interpreted too. In the last Chapter, a kind of MIMO HRWS SAR combining DPCMAB and concurrent-sub-band modes is introduced, research work such as echo data generation, data fusing and SAR imaging are implemented, simulation work demonstrates the excellent capability of 2D high resolution imaging of the new SAR system.更多还原