In order to enhance the robustness and contrast in the minimum variance(MV) beamformer, adaptive diagonal loading method was proposed. The conventional diagonal loading technique has already been used in the MV beamfo...In order to enhance the robustness and contrast in the minimum variance(MV) beamformer, adaptive diagonal loading method was proposed. The conventional diagonal loading technique has already been used in the MV beamformer, but has the drawback that its level is specified by predefined parameter and without consideration of input-data. To alleviate this problem, the level of diagonal loading was computed appropriately and automatically from the given data by shrinkage method in the proposed adaptive diagonal loaded beamformer. The performance of the proposed beamformer was tested on the simulated point target and cyst phantom was obtained using Field II. In the point target simulation, it is shown that the proposed method has higher lateral resolution than the conventional delay-and-sum beamformer and could be more robust in estimating the amplitude peak than the MV beamformer when acoustic velocity error exists. In the cyst phantom simulation, the proposed beamformer has shown that it achieves an improvement in contrast ratio and without distorting the edges of cyst.展开更多
The derivation of a diagonally loaded sample-matrix inversion （LSMI） algorithm on the busis of inverse matrix recursion （i.e.LSMI-IMR algorithm） is conducted by reconstructing the recursive formulation of covarian...The derivation of a diagonally loaded sample-matrix inversion （LSMI） algorithm on the busis of inverse matrix recursion （i.e.LSMI-IMR algorithm） is conducted by reconstructing the recursive formulation of covariance matrix. For the new algorithm, diagonal loading is by setting initial inverse matrix without any addition of computation. In addition, a corresponding improved recursive algorithm is presented, which is low computational complexity. This eliminates the complex multiplications of the scalar coefficient and updating matrix, resulting in significant computational savings. Simulations show that the LSMI-IMR algorithm is valid.展开更多
当阵列误差存在时,Capon波束形成算法性能会急剧下降,特别是阵列输出信干噪比(signal to interfer-ence plus noise ratio,SINR)。对角加载可以减弱小特征值对应的噪声波束的影响,能有效改善阵列性能及方向图畸变,但加载值的确定是一个...当阵列误差存在时,Capon波束形成算法性能会急剧下降,特别是阵列输出信干噪比(signal to interfer-ence plus noise ratio,SINR)。对角加载可以减弱小特征值对应的噪声波束的影响,能有效改善阵列性能及方向图畸变,但加载值的确定是一个较为困难的问题。该算法根据加载值和采样协方差矩阵间的关系确定加载值,能自适应地根据采样数据确定加载值,在小快拍数和阵列误差存在情况下仍具有良好的鲁棒性,明显改善了阵列性能并减小了方向图畸变,且使零陷准确对准干扰方向。计算机仿真结果证实了此算法的鲁棒性。展开更多
基金Project(2013GZX0147-3)supported by the Science and Technology Pillar Program of Sichuan Province,China
文摘In order to enhance the robustness and contrast in the minimum variance(MV) beamformer, adaptive diagonal loading method was proposed. The conventional diagonal loading technique has already been used in the MV beamformer, but has the drawback that its level is specified by predefined parameter and without consideration of input-data. To alleviate this problem, the level of diagonal loading was computed appropriately and automatically from the given data by shrinkage method in the proposed adaptive diagonal loaded beamformer. The performance of the proposed beamformer was tested on the simulated point target and cyst phantom was obtained using Field II. In the point target simulation, it is shown that the proposed method has higher lateral resolution than the conventional delay-and-sum beamformer and could be more robust in estimating the amplitude peak than the MV beamformer when acoustic velocity error exists. In the cyst phantom simulation, the proposed beamformer has shown that it achieves an improvement in contrast ratio and without distorting the edges of cyst.
文摘The derivation of a diagonally loaded sample-matrix inversion （LSMI） algorithm on the busis of inverse matrix recursion （i.e.LSMI-IMR algorithm） is conducted by reconstructing the recursive formulation of covariance matrix. For the new algorithm, diagonal loading is by setting initial inverse matrix without any addition of computation. In addition, a corresponding improved recursive algorithm is presented, which is low computational complexity. This eliminates the complex multiplications of the scalar coefficient and updating matrix, resulting in significant computational savings. Simulations show that the LSMI-IMR algorithm is valid.
文摘当阵列误差存在时,Capon波束形成算法性能会急剧下降,特别是阵列输出信干噪比(signal to interfer-ence plus noise ratio,SINR)。对角加载可以减弱小特征值对应的噪声波束的影响,能有效改善阵列性能及方向图畸变,但加载值的确定是一个较为困难的问题。该算法根据加载值和采样协方差矩阵间的关系确定加载值,能自适应地根据采样数据确定加载值,在小快拍数和阵列误差存在情况下仍具有良好的鲁棒性,明显改善了阵列性能并减小了方向图畸变,且使零陷准确对准干扰方向。计算机仿真结果证实了此算法的鲁棒性。
