Sub-aperture Keystone Transform Based Echo Simulation Method for High-squint SAR with a Curve Trajectory
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摘要: 大机动条件下的曲线轨迹大斜视SAR系统传递函数具有复杂的多维空变性，现有的高效频域回波模拟算法均难以实现扩展场景的高精度回波模拟。为此，该文提出一种基于子孔径Keystone变换的机动SAR回波模拟方法。该方法根据距离徙动校正后的距离压缩函数对场景的距离压缩回波进行快速模拟，然后通过高精度的距离向逆处理实现扩展场景的回波模拟。为减少残余距离徙动对回波模拟精度的影响，距离向处理过程中采用子孔径Keystone变换的方法实现空变距离徙动的精确校正。理论分析和仿真结果表明，所提方法能够快速高精度地模拟扩展场景的机动平台大斜视SAR原始回波数据。
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关键词:
- SAR /
- 回波模拟 /
- 曲线轨迹 /
- 子孔径Keystone变换
Abstract: The system transfer function of high-squint SAR system with curved trajectory has complex multi-dimensional spatial variability. The existing efficient frequency-domain echo simulation algorithms are difficult to achieve high-precision echo simulation of extended scenes. Therefore, a fast echo simulation method based on sub-aperture Keystone transform is proposed for maneuvering SAR. Based on the time-domain range compression function after range cell migration correction, the method calculates efficiently the range compression echo of scene, and then realizes the echo simulation of extended scene by high precision range inverse processing. In order to reduce the influence of residual range cell migration on the accuracy of echo simulation, the method of the Keystone transform of sub-aperture is used in range processing to achieve accurate correction of space-variant range cell migration in extended scenes. The theoretical analysis and simulation results show that the proposed method can quickly and accurately simulate the original echo data of extended scenes for high-squint SAR mounted on a maneuvering platform.-
Key words:
- SAR /
- Echo simulation /
- Curve trajectory /
- Sub-aperture Keystone transform
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表 1 仿真参数
SAR系统参数 数值 运动参数 数值 载频 15 GHz 斜视角 60° 距离带宽 300 MHz 平台高度 4 km 距离过采样因子 1.2 中心斜距 13 km 合成孔径时间 3 s 速度 (150, 0, –35) m/s 脉冲宽度 5 µs 加速度 (2.2, 1.2, –0.8) m/s2 脉冲重复频率 2 kHz 加加速度 (0.2, 0.1, –0.1) m/s3 天线波束宽度 14° 
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表 2 点目标的方位向测量指标量化分析结果
点目标 PARE MWRE PSLRE(dB) ISLRE(dB) 1 1.3e-03 1.0e-04 6.1e-03 –2.8e-03 2 5.2e-06 1.0e-06 7.1e-06 8.7e-06 3 1.2e-05 2.1e-06 1.4e-04 3.2e-05 4 1.5e-04 5.2e-06 6.5e-04 6.8e-05
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