双基星载合成孔径雷达(SAR)利用双平台接收以及联合处理回波信号,在测绘、干涉测量、目标识别、自然灾害监测等领域有重要的应用价值.为了进一步提升该体制的成像性能,该文提出一种采用空时编码和短偏移正交波形的双基星载多发多收合成孔径雷达系统(MIMO SAR).基于接收端的数字波束形成技术,该系统能够有效分离提取不同波形回波数据,获取更多空间自由度,从而同时具备双基体制和MIMO体制的优势.此外,通过对获取的不同波形图像数据做波束形成处理,该系统能够减轻2次散射干扰回波对SAR图像的影响.仿真实验验证了该系统方案的有效性.%Benefiting from the combined processing of echo signals received on spatially separated platforms, bistatic spaceborne SAR has many valuable applications such as survey, interferometry, target recognition and classification, disaster monitoring, etc. In order to improve the imaging performance further, this paper presents a bistatic spaceborne Multiple-Input Multiple-Output SAR (MIMO SAR) system combined with Space-Time Coding (STC) and Short-Term Shift-Orthogonal (STSO) chirp waveforms. With the help of digital beamforming techniques on receive, different transmitting waveforms can be separated and extracted from mixed echoes, so that such enhanced architecture can achieve the advantages of both bistatic and MIMO configuration from more spatial degrees of freedom. Furthermore, it offers an opportunity for mitigating the influences of double-bounce scattering by using beamforming on multiple SAR images. The theoretical analysis is derived in detail, then validated by simulation experiments.
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