Abstract: A novel Direction Of Arrival（DOA） estimation method is proposed with Uniform Linear Array（ULA） when mixed sources are presented.The DOAs of uncorrelated signals are first estimated by using conventional multiple signal classification（MUSIC）.Afterwards，the coherent signals can be resolved by performing the improved spatial smoothing technique to the constructed spatial differenced matrix，which eliminates the contributions of uncorrelated signals and noises.Discussions are provided for both one and multiple groups of coherent sources.The number of sources resolved by this method can exceed the number of array elements.Simulation results demonstrate that the proposed method is effective，robust and outperforms the existing spatial differencing smoothing method.

Key words: Uniform Linear Array（ULA）, coherent sources, Direction-Of-Arrival（DOA）, spatial smoothing technique, negative-cross-symmetric matrix

摘要： 提出了一种基于均匀线阵的混合源波达方向DOA估计的新方法。该方法首先利用传统MUSIC方法估计出非相干信号源的DOA，然后对整个阵列数据协方差矩阵进行差分消除不相关源信号和噪声的影响，再对此差分矩阵进行特殊的空间平滑去相干，利用重建的数据协方差矩阵估计相干源的DOA。此方法的特点是分别估计不相关信号和相干信号的DOA，优点是在可估计出多于阵元数信号的前提下具有较高的DOA估计精度和稳健性。理论分析和仿真结果表明此方法的估计性能优于空间差分平滑算法。

关键词: 均匀线阵, 相干源, 波达方向, 空间平滑技术, 负反对称矩阵