School of Electronic & Information Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China.
Science and Technology on Microwave Imaging Laboratory, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China.
Sensors (Basel). 2018 Oct 22;18(10):3580. doi: 10.3390/s18103580.
In recent years, multi-input multi-output (MIMO) synthetic aperture radar (SAR) systems, which can promote the performance of 3D imaging, high-resolution wide-swath remote sensing, and multi-baseline interferometry, have received considerable attention. Several papers on MIMO-SAR have been published, but the research of such systems is seriously limited. This is mainly because the superposed echoes of the multiple transmitted orthogonal waveforms cannot be separated perfectly. The imperfect separation will introduce ambiguous energy and degrade SAR images dramatically. In this paper, a novel orthogonal waveform separation scheme based on echo-compression is proposed for airborne MIMO-SAR systems. Specifically, apart from the simultaneous transmissions, the transmitters are required to radiate several times alone in a synthetic aperture to sense their private inner-aperture channels. Since the channel responses at the neighboring azimuth positions are relevant, the energy of the solely radiated orthogonal waveforms in the superposed echoes will be concentrated. To this end, the echoes of the multiple transmitted orthogonal waveforms can be separated by cancelling the peaks. In addition, the cleaned echoes, along with original superposed one, can be used to reconstruct the unambiguous echoes. The proposed scheme is validated by simulations.
近年来，多输入多输出（MIMO）合成孔径雷达（SAR）系统受到了相当的关注，因为它可以提高三维成像、高分辨率宽测绘带遥感和多基线干涉测量的性能。已经有几篇关于 MIMO-SAR 的论文发表，但这种系统的研究受到了严重的限制。这主要是因为多个发射正交波形的叠加回波不能完美分离。不完美的分离会引入模糊能量，从而大大降低 SAR 图像的质量。在本文中，我们针对机载 MIMO-SAR 系统提出了一种基于回波压缩的新的正交波形分离方案。具体来说，除了同时发射之外，发射机还需要在合成孔径中单独辐射几次，以感知它们的私有内部孔径信道。由于相邻方位位置的信道响应是相关的，因此在叠加回波中单独辐射的正交波形的能量将集中。为此，可以通过消除峰值来分离多个发射的正交波形的回波。此外，经过清洗的回波以及原始的叠加回波，可以用于重建无模糊的回波。所提出的方案通过仿真得到了验证。
