说明：  “完全可增强”稀疏线阵入射多个不相关平面波的波达角方向(DOA)估计问题。在估计阶段之前确定了现有信号源(M)的数目，研究了在最大似然意义下DOA估计精度有效的条件。
(The problem of DOA estimation for incoherent plane waves incident by sparse linear arrays with "fully enhanced" effect is discussed. The number of existing signal sources (M) is determined before the estimation stage, and the conditions for the accuracy of DOA estimation in the maximum likelihood sense are studied.)