说明：  DOA估计，一种基于矩阵特征空间分解的方法。从几何角度讲，信号处理的观测空间可以分解为信号子空间和噪声子空间，显然这两个空间是正交的。信号子空间由阵列接收到的数据协方差矩阵中与信号对应的特征向量组成，噪声子空间则由协方差矩阵中所有最小特征值（噪声方差）对应的特征向量组成。
(DOA estimation, a method based on matrix eigenspace decomposition. From the geometric point of view, the observation space of signal processing can be divided into signal subspace and noise subspace, which are obviously orthogonal. The signal subspace consists of the eigenvectors corresponding to the signal in the data covariance matrix received by the array, and the noise subspace consists of the eigenvectors corresponding to all the minimum eigenvalues (noise variance) in the covariance matrix.)