说明：  DOA谱估计实值MUSIC算法把复数协方差矩阵映射成实数矩阵来处理，特征值分解计算量降低了75 ，实值music算法可以分辨相干信号源
(DOA in real MUSIC spectral estimation algorithm to map the complex covariance matrices to deal with real, eigenvalue decomposition calculation reduced by 75 , real music algorithm can distinguish between coherent signal source)