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摘要:
在近程大斜视成像中，当采用距离徙动（RM）算法进行处理时，信号谱在有限谱域范围内发生偏移，引起多次翻折造成混叠，使得通常处理方式不再适用。为此，提出一种解混叠方法恢复实际信号谱，通过斜视角或目标中心偏移量可计算出信号谱的翻折次数，依据翻折次数可将信号谱恢复至实际谱域位置，进而依照RM算法流程进行处理即可实现大斜视成像。该算法基于信号谱进行，未对距离方程进行近似处理，因此不仅适用于远场，同时可以解决近程大斜视成像问题。计算机仿真和实际实验测量结果显示，采用本文算法处理后可对成像范围内的目标实现精确聚焦。本文算法适用近程条件下阵列雷达或合成孔径雷达（SAR）的大斜视成像问题，可对较大斜视角情况实现精确聚焦。同时，本文算法的流程清晰，易于实际编程实现。
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关键词:
- 距离徙动(RM)算法 /
- 近程成像 /
- 大斜视 /
- 谱域 /
- 合成孔径雷达(SAR)
Abstract:In the case of short-range high squint imaging, the conventional range migration (RM) algorithm cannot be adopted directly, for the reason that the spatial spectrum will shift in the limited spatial spectrum domain and will cause warping and aliasing several times. In order to solve this problem, an algorithm to restore the actual spatial spectrum was presented. Times of warping spectrum were calculated exactly according to the squint angle or the shift of the target in azimuth to help shifting back to the actual position in the spatial spectrum domain. Then this algorithm could be completed as the step of RM algorithm. The modified algorithm can not only satisfy far field condition, but also can be successfully used for short-range high squint mode, because of the spectrum processing procedure and non-approximation of the distance equation. Both the simulation and experimental results show that the modified algorithm can accurately focus the target in the imaging scene. This algorithm can solve high squint imaging problem for short-range synthetic aperture radar (SAR).Meanwhile, the algorithm procedure is clear and easy to be realized by programming.
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图 2 斜视场景下仿真参数设计示意图
Figure 2. Schematic of simulation parameter design in squint condition
图 3 阵列中心与成像区域中心无偏和30°斜视角的频谱对比
Figure 3. Comparison of spectrum between no squint angle and with squint angle of 30°
图 7 谱域不同部分翻折次数
Figure 7. Warping and lapping times of differentparts of spectral domain
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