Investigation on PRI Variation for High Squint Spaceborn Spotlight SAR
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摘要: 星载SAR大斜视聚束可以实现高分辨率宽覆盖成像和目标多方位信息获取,但斜视情况下大距离徙动会造成回波数据获取效率下降、波位选择困难等问题。变PRI技术可以跟踪聚束成像过程中目标斜距变化,提高数据获取效率、降低波位选择难度。该文对星载大斜视聚束SAR的变PRI工作机理进行了研究,提出了一种PRI变化序列迭代设计方法和波位选择策略,研究了样条插值和NUFFT两种非周期非均匀采样重建方法,并首次通过机载飞行试验对所提出的变PRI的SAR系统工作体制进行了验证。Abstract: High squint spotlight mode of spaceborne SAR can be used to achieve high resolution and wide swath, and also can be used to acquire information of target from multi-azimuth. However, the considerable range migration can result in efficiency decreasing in data acquisition, and dilemma in system design. This problem can be solved by the technology named PRI (Pulse Repetition Interval) variation which can track the slant range variation of the target during data acquisition. In this paper, the principle of PRI variation is studied, and methods of PRI sequence iterative design and system parameter selection are proposed. Two approaches to reconstruct the nonequal spaced and nonperiod data in azimuth sampling are compared. Finally, the first results of PRI variation mode of airborne SAR experiment with high slant spotlight mode are presented.
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Key words:
- SAR /
- Pulse Repetition Interval (PRI) variation /
- High squint spotlight /
- Spaceborne /
- Airborne
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表 1 星载SAR仿真参数
参数名称 符号 取值 中心频率 ${f_c}$ 9600 MHz 卫星高度 $H$ 800 km 卫星速度 ${V_s}$ 7486 m/s 雷达下视角 ${\alpha _0}$ 30° 发射脉宽 ${T_p}$ 20 μs 天线长度 ${L_a}$ 10 m 天线高度 ${L_r}$ 2 m 表 2 两种重建方法性能比较
均匀采样 样条插值重建 NUFFT重建 主瓣展宽比ML 1.00 1.01 1.00 峰值旁瓣比PSLR (dB) –13.27 –13.82 –13.26 积分旁瓣比ISLR (dB) –9.72 –10.67 –9.72 均方误差(%) 0.00 0.26 0.0119 -
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