Precise Imaging Processing for Spaceborne Spotlight SAR
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摘要: 分析了星载聚束式合成孔径雷达(SAR)的信号特性,主要研究了多普勒中心频率、多普勒带宽以及脉冲重复频率(PRF)与斜视角的关系.基于改进的Chirp Scaling算法,处理时采用了子孔径方法.通过子孔径方法,可以有效降低数据率及雷达发射峰值功率,并可解决多普勒中心频率的时变问题.此外,分析了偏航控制对于实现精确成像的必要性,给出偏航控制规律,证明偏航控制可以有效减小距离徙动量,降低成像处理难度.最后,通过计算机仿真,验证了处理方法的有效性.Abstract: Signal properties of spaceborne spotlight SAR were discussed. The relationships of centroid Doppler, Doppler bandwidth and PRF(Pluse Repetition Frequency) with squint angle were analyzed. Based on a modified Chirp Scaling algorithm, a subaperture method was used in this algorithm. With the subaperture method, data rate and radar transmit peak power can be effectively reduced, the time-variant of Doppler center frequency can be resolved. In addition, the necessities of yaw steering were analyzed, a yaw steering rule was given. It was proved that yaw steering can be used to decrease range migration and to reduce imaging difficulties. The validity of the processing method was tested by computer simulation.
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Key words:
- synthetic aperture radar /
- image formation /
- yaw steering /
- subaperture method
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[1] Carrara W G, Goodman R S, Majewski R M. Spotlight synthetic aperture radar[M]. London:Artech House, 1995. 81~471. [2]黄 岩, 李春升, 陈 杰, 等. 高分辨星载SAR改进Chirp Scaling成像算法 . 电子学报, 2000, 28(3):35~38. [3]Davidson G W, Cumming I. Signal properties of spaceborne squint-mode SAR[J]. IEEE Transactions on Geoscience Remote Sensing, 1997, 35(5):611~617. [4]Mittermayer J, Moreira A, Loffeld O. Spotlight SAR data processing using the frequency scaling algorithm[J]. IEEE Transactions on Geoscience Remote Sensing, 1999, 37(5):2198~2214. -
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