Digital Beamforming on Receive: Techniques and Optimization Strategies for High-Resolution Wide-Swath SAR Imaging
Digital Beamforming on Receive: Techniques and Optimization Strategies for High-Resolution Wide-Swath SAR Imaging
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DOI：
10.1109/taes.2009.5089542
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发表时间：
2009-04-01
影响因子：
4.4
通讯作者：
Moreira, Alberto
中科院分区：
文献类型：
--
作者：
Gebert, Nicolas;Krieger, Gerhard;Moreira, Alberto
合成孔径雷达(SAR)是一种成熟的地球遥感成像技术。然而，传统的合成孔径雷达系统不能满足日益增长的空间分辨率和更宽的测绘带覆盖范围的需求。为了克服这些固有的局限性，已经提出了几种创新的技术，它们使用多个接收孔径来沿着合成孔径收集额外的信息。综述了这些数字波束形成(DBF)的接收技术，重点讨论了方位向多孔径信号的处理，并提出了一种多孔径重建算法，该算法能够准确地恢复多普勒谱。研究了多普勒混叠的影响，推导了剩余方位模糊度的解析表达式。进一步，分析了处理对信噪比(SNR)的影响，得到了描述多孔径波束形成网络的SNR定标的脉冲重复频率(PRF)相关因子。然后将重点转向一个完整的高分辨率宽测绘带合成孔径雷达系统设计实例，展示了多孔径方位处理与系统结构之间的复杂联系。在这一点上，比较了不同的处理方法和多孔径重建算法。在下一步中，讨论了方向图渐变、接收时预波束整形和改进的处理算法等优化策略。在此背景下，将剩余模糊度和信噪比比例因子的解析表达式推广到级联波束形成网络中。此外，建议的技术还可以在许多方面进行扩展。讨论的示例是与ScanSAR突发模式操作的组合以及向多基地稀疏阵列配置的转换。
Synthetic Aperture Radar (SAR) is a well-proven imaging technique for remote sensing of the Earth. However, conventional SAR systems are not capable of fulfilling the increasing demands for improved spatial resolution and wider swath coverage. To overcome these inherent limitations, several innovative techniques have been suggested which employ multiple receive-apertures to gather additional information along the synthetic aperture. These digital beamforming (DBF) on receive techniques are reviewed with particular emphasis on the multi-aperture signal processing in azimuth and a multi-aperture reconstruction algorithm is presented that allows for the unambiguous recovery of the Doppler spectrum. The impact of Doppler aliasing is investigated and an analytic expression for the residual azimuth ambiguities is derived. Further, the influence of the processing on the signal-to-noise ratio (SNR) is analyzed, resulting in a pulse repetition frequency (PRF) dependent factor describing the SNR scaling of the multi-aperture beamforming network. The focus is then turned to a complete high-resolution Wide-swath SAR system design example which demonstrates the intricate connection between multi-aperture azimuth processing and the system architecture. In this regard, alternative processing approaches are compared with the multi-aperture reconstruction algorithm. In a next step, optimization strategies are discussed as pattern tapering, prebeamshaping-on-receive, and modified processing algorithms. In this context, the analytic expressions for both the residual ambiguities and the SNR scaling factor are generalized to cascaded beamforming networks. The suggested techniques can moreover be extended in many ways. Examples discussed are a combination with ScanSAR burst mode operation and the transfer to multistatic sparse array configurations.