Broadband Fusion of Multiband Radar Signals Based on Optimal Dictionary Selection
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摘要: 多频段雷达带宽融合外推是一种提升雷达带宽、解决小目标高分辨成像的有效手段。然而,现有多频段融合算法仍面临运算慢、精度低等问题。为此,该文提出基于最优字典选择正交匹配追踪的多频段融合外推雷达超分辨距离成像方法。首先,对多频段信号进行参数化建模,提出基于蛇优化的信号相参配准方法,实现多频段信号高精度相位对齐;然后,利用几何绕射模型,提出基于最优字典选择正交匹配追踪的多频段信号模型估计方法,实现多频段信号融合外推,估计未知频段频谱,获取大带宽信号;最后,通过仿真和实测数据,验证了该方法的可行性。该方法在保障高精度的前提下,通过简化模型粗估计与完整模型精估计结合,有效降低了运算量,实现了快速精确多频段融合外推处理。Abstract: Multiband Fusion is an effective way to broaden bandwidth of radar, which plays a key role in the detection and recognition of small-scale target. However, the existing multiband fusion algorithms still face the problems of slow operation and low precision. Therefore, a super-resolution technique of multiband fusion based on optimal dictionary selection and orthogonal matching pursuit is proposed in this paper. Firstly, the parametric model of multiband radar signal is conducted. Next, Snake Optimizer (SO) is applied to the coherent processing. Then, an Orthogonal Matching Pursuit (OMP) algorithm based on the optimal Geometrical Theory of Diffraction (GTD) dictionary selection is used to extrapolate the vacant spectrum. Experiment results of simulated and measured data are given. Experimental results show that the proposed method can effectively achieve super-resolution. This method combines simplified model rough estimation with complete model fine estimation, effectively reducing the amount of computation and realizing fast and accurate multiband fusion extrapolation processing.
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表 1 频率依赖因子取值表
散射机理类型 频率依赖因子取值 平板、二面角、三面角的反射 1 单弯曲曲面的反射 0.5 双弯曲曲面的反射、直边的绕射 0 曲边的绕射 –0.5 尖顶、角的绕射 –1 1 蛇优化算法
初始化:设置基本参数:参数维度dim,设定自变量取值范围 ,种群中个体数量为N,最大迭代次数T,当前迭代次数t,初始t=1。在定
义域内随机建立初始种群。种群划分:将完整种群中个体划分为两个种群。 迭代流程: (1) 参量计算:按式(6)计算温度temp,按式(7)计算食物位置P。 (2) 更新判断:首先判断P情况:当P< 0.25时,执行步骤3;当P > 0.6时,执行步骤4;其余情况,执行步骤5。 (3) 情景1(P< 0.25):按式(8)–式(11)执行更新。跳转到步骤6,执行判断。 (4) 情景2(P > 0.6):按式(12)–式(13)执行更新。跳转到步骤6,执行判断。 (5) 情景3(P的其余取值情况):当随机数rand 大于0.6,按式(14)–式(15)执行更新;反之,按式(16)–式(17)执行更新。执行步骤6。 (6) 判断:淘汰劣势个体,当迭代次数达到结束要求(或种群适应度变化小于设定阈值)时,迭代结束。 输出:最优相参估计值$ {X_{{\mathrm{food}}}} $。 表 2 仿真多频段参数设置
频段1 频段2 外推宽带 频段 (GHz) 9~10 11~12 9~12 频点间隔 (MHz) 20 20 20 频点个数 51 51 151 线性相位误差 (rad) / 0.3 / 固定相位误差 (rad) / 1.0 / 表 3 外场多频段处理参数设置
X1频段 X2频段 外推宽带 频段(GHz) 9~10 11~12 9~12 频点间隔(MHz) 5 5 5 频点个数 201 201 601 表 4 实测角反间距(cm)
X1频段(9~10 GHz) X2频段(11~12 GHz) 本文方法(9~12 GHz) 传统方法(9~12 GHz) 17.07 cm间距 角反射器测量间距 21.36 19.81 16.53 16.00 12.33 cm间距 角反射器测量间距 \ \ 13.86 14.40 -
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