虚拟波束四阶累积量DOA估计方法

为满足复杂干扰场景和阵列误差因素影响下雷达微弱目标信号精确测向需求，提出一种基于均匀线阵构建虚拟波束，替代阵列接收信号进行四阶累积量(fourth-order cumulant, FOC)波达方向(direction of arrival, DOA)估计的算法。该算法包括两个关键步骤：一是利用阵列接收信号特征分解的方法，对信号主信息分量进行提取，并以构建的虚拟波束为输入，计算FOC矩阵；二是针对主分量虚拟波束波瓣外的起伏，利用高斯窗修正波束方向图的方法，进一步提升空间谱函数的估计精度。仿真结果表明，该方法在存在阵列误差的非理想因素下，对复杂电磁干扰场景下的目标信号DOA估计精度较现有FOC方法提高150%以上，尤其对于场内同时存在多个非等功率源信号时，所提方法对低信噪比目标DOA估计精度提升效果优势明显，对复杂干扰环境下DOA估计精度更高、适应性更强。

DOA estimation algorithm based on fourth-order cumulant using virtual beam forming

In order to meet the requirements of precise direction finding of radar weak target signal under the influence of complex interference and array error factors, an algorithm of constructing virtual beam based on uniform linear array to replace the array received signal for fourth-order cumulant (FOC) direction of arrival (DOA) estimation is proposed.The algorithm includes two key steps: one is to extract the main information component of the signal by using the method of feature decomposition of the array received signal, and calculate the FOC matrix with the constructed virtual beam as the input. The other aiming at the fluctuation outside the lobe of the principal component virtual beam, is to use Gaussian window to modify the beam pattern to further improve the estimation accuracy of the spatial spectral function. The simulation results show that under the non ideal factors of array error, the DOA estimation accuracy of the target signal in the complex electromagnetic interference scene is more than 150% higher than that of the existing FOC method. Especially when there are multiple non equal power source signals in the field at the same time, the proposed method has obvious advantages in improving the DOA estimation accuracy of the target with low signal-to-noise ratio, and has higher DOA estimation accuracy and stronger adaptability in the complex interference environment.