非均匀对角减载最小方差无失真响应多目标分辨

针对最小方差无失真响应(Minimum Variance Distortionless Response,MVDR)方法在起伏非相关噪声环境下多目标分辨性能严重下降的问题,提出一种非均匀对角减载MVDR (Inhomogeneous Diagonal Unloading MVDR,IDU-MVDR)方法。该方法首先对协方差矩阵进行非均匀对角减载,然后实施MVDR方法。各阵元上的对角减载量通过求解半正定优化问题获得,优化问题中最大化减载量之和,但约束减载后协方差矩阵的最小特征值是一个较小的正值。数值仿真表明,IDUMVDR方法可通过非均匀对角减载消除大部分非相关噪声,但保留小部分噪声分量.因此IDU-MVDR方法较MVDR方法分辨力更高,空间谱中背景级更低、弱目标谱峰更加明显,并且具备一定的稳健性.海上实验结果与数值仿真相一致,验证了IDU-MVDR方法的有效性. 

Minimum variance distortionless response multi-source resolving using inhomogeneous diagonal unloading

Under some underwater situations,the multi-source resolving performance of the Minimum Variance Distortionless Response(MVDR) method could seriously degrade due to the strong and inhomogeneous uncorrelated noise on the hydrophone array.To mitigate this problem,we propose an Inhomogeneous Diagonal Unloading MVDR(IDUMVDR) method,where inhomogeneous diagonal unloading is applied on the covariance matrix before applying the MVDR method.The diagonal unloading level for each array element is obtained by solving a positive semi-definite optimization problem,where we maximize the sum of the diagonal unloading levels while constraining the minimum eigenvalue of the unloaded covariance matrix to be a small positive value.The numerical simulations suggested that the proposed IDU-MVDR method can remove most of the uncorrelated noise while remaining a small amount of which on the array elements.In consequence,the IDU-MVDR method provides higher resolution,lower background level,more distinct peaks and guaranteed robustness compared to the MVDR method.The sea trial results agreed well with the numerical simulations and proved the vitality of the IDU-MVDR method.