基于频谱旋转ωk算法的大斜视SAR地面动目标成像

doi:10.12305/j.issn.1001-506X.2022.10.14

摘要/Abstract

摘要：

针对大斜视条件下合成孔径雷达(synthetic aperture radar, SAR)地面运动目标成像存在的聚焦困难、几何形变严重、十字旁瓣大等问题, 提出一种基于频谱旋转ωk算法的大斜视SAR动目标成像算法。首先, 在推导具有精确斜距表达式的斜视动目标回波信号模型的基础上, 获得了初步成像结果并提取动目标的感兴趣区域(region of interest, ROI)数据。然后, 构造相位补偿函数并利用最小熵算法完成动目标参数估计, 再根据估计的参数对ROI数据进行相位补偿, 获得聚焦的动目标图像。进一步利用频谱旋转消除了几何形变, 利用稀疏增强方法减小了动目标旁瓣, 最终得到聚焦、无几何形变、低旁瓣的动目标图像。仿真实验验证了所提算法的有效性。

关键词: 合成孔径雷达, 地面动目标成像, 大斜视, ωk算法, 频谱旋转

Abstract:

To solve the problem of difficult focus, serious geometry distortion and large cross sidelobe in high-squint mode synthetic aperture radar (SAR) ground moving target imaging (GMTIm), a high-squint SAR GMTIm algorithm based on the ωk algorithm with spectrum rotation is proposed. Firstly, a moving target echo signal model with accurate slant-range is deduced in detail to obtain preliminary imaging result and extract the region of interest (ROI) moving target data. Then, the phase compensation function is constructed and the minimum entropy algorithm is utilized to finish moving target parameter estimation. According to the estimated parameter, the phase of ROI data is compensated to get the focused moving target image. Furthermore, spectrum rotation eliminates geometry distortion, and the sparsity enhancement method decreases the moving target sidelobe. By doing so, focused, no geometry distortion and low sidelobe moving target image is obtained. Simulation results validate the effectiveness of the proposed algorithm.

Key words: synthetic aperture radar (SAR), ground moving target imaging (GMTIm), high-squint mode, ωk algorithm, spectrum rotation

中图分类号:

TN957.5

熊世超, 倪嘉成, 张群, 罗迎. 基于频谱旋转ωk算法的大斜视SAR地面动目标成像[J]. 系统工程与电子技术, 2022, 44(10): 3104-3114.

Shichao XIONG, Jiacheng NI, Qun ZHANG, Ying LUO. High-squint mode SAR GMTIm based on ωk algorithm with spectrum rotation[J]. Systems Engineering and Electronics, 2022, 44(10): 3104-3114.

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[v_x, v_r]	β	[v_x, v_r]	β
[0, 0]	4.444×10^－5	[40, －40]	7.299×10^－5
[0, 40]	4.149×10^－5	[－40, 0]	2.770×10^－5
[0, －40]	4.149×10^－5	[－40, 40]	2.653×10^－5
[40, 0]	8.265×10^－5	[－40, －40]	2.653×10^－5
[40, 40]	7.299×10^－5	-	-

性能指标	成像方法	P₁, V₁	P₂, V₁	P₁, V₂	P₂, V₂
峰值旁瓣比	无频谱旋转	-12.95	-12.81	-12.99	-12.86
峰值旁瓣比	频谱旋转	-13.36	-13.25	-13.29	-13.16
积分旁瓣比	无频谱旋转	-9.36	-9.24	-9.37	-9.25
积分旁瓣比	频谱旋转	-9.81	-9.86	-9.81	-9.74

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