Zhang Qianghui, Wu Junjie, Li Wenchao, Huang Yulin, Yang Jianyu, Yang Haiguang
School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
Sensors (Basel). 2016 Jul 27;16(8):1177. doi: 10.3390/s16081177.
Free of the constraints of orbit mechanisms, weather conditions and minimum antenna area, synthetic aperture radar (SAR) equipped on near-space platform is more suitable for sustained large-scene imaging compared with the spaceborne and airborne counterparts. Terrain observation by progressive scans (TOPS), which is a novel wide-swath imaging mode and allows the beam of SAR to scan along the azimuth, can reduce the time of echo acquisition for large scene. Thus, near-space TOPS-mode SAR (NS-TOPSAR) provides a new opportunity for sustained large-scene imaging. An efficient full-aperture imaging scheme for NS-TOPSAR is proposed in this paper. In this scheme, firstly, two-step processing (TSP) is adopted to eliminate the Doppler aliasing of the echo. Then, the data is focused in two-dimensional frequency domain (FD) based on Stolt interpolation. Finally, a modified TSP (MTSP) is performed to remove the azimuth aliasing. Simulations are presented to demonstrate the validity of the proposed imaging scheme for near-space large-scene imaging application.
近空间平台上配备的合成孔径雷达（SAR）不受轨道机制、天气条件和最小天线面积的限制，与星载和机载合成孔径雷达相比，更适合进行持续的大场景成像。逐行扫描地形观测（TOPS）是一种新型的宽测绘带成像模式，它允许合成孔径雷达的波束沿方位向扫描，可以减少大场景回波采集时间。因此，近空间TOPS模式合成孔径雷达（NS-TOPSAR）为持续的大场景成像提供了新的机遇。本文提出了一种针对NS-TOPSAR的高效全孔径成像方案。在该方案中，首先采用两步处理（TSP）来消除回波的多普勒混叠。然后，基于Stolt插值在二维频域（FD）对数据进行聚焦。最后，执行改进的两步处理（MTSP）以消除方位向混叠。通过仿真验证了所提成像方案在近空间大场景成像应用中的有效性。
