自适应波束形成中对角加载方法研究
摘 要
总所周知，当快拍数较少时，自适应波束形成算法的性能会下降，甚至会造成信号对消现象。对角加载（diagonal loading）方法是阵列信号处理中常用到的一种提高算法稳健性的方法，该算法不仅实现简单，而且效果也比较好，它能补偿阵列误差、估计误差和小快拍造成的采样协方差矩阵的误差。
波束形成技术和信号空间波数谱估计是自由空间信号阵列处理的两个主要研究方面。MVDR是一种基于最大信干噪比（SINR）准则的自适应波束形成算法。MVDR算法可以自适应的使阵列输出在期望方向上功率最小同时信干噪比最大。将其应用于空间波数谱估计上可以在很大程度上提高分辨率和噪声抑制性能。本文将在深入分析MVDR算法原理的基础上，通过计算机仿真和海上试验数据处理的结果，分析了MVDR算法在高分辨率空间波数谱估计应用中的性能。同时通过比较对角加载前后的数据处理结果，分析对角加载对MVDR的改进效果。
本课题的目的就是系统研究目前在自适应信号处理领域用到的各种对角加载方法，研究各种对角加载的加载量（loading level）的计算方法和各种对角加载方法的特点，并对性能进行比较，给出结论。
关键词：波束形成；空间波数谱估计；MVDR；对角加载
Abstract
Is well known that when the snapshot of a small number of adaptive beamforming algorithm performance will decline and may even cause the signal cancellation phenomenon. (Diagonal loading) of diagonal loading method is used to array signal processing method to improve the algorithm robustness, the algorithm is not only simple, but the effect is relatively good, it can compensate for array errors, estimated error and a small snapshot caused by sampling error covariance matrix.
Beamforming and signal space wavenumber spectrum estimation is the free space signal array processing research. MVDR is based on the maximum letter noise ratio (SINR) criteria for the adaptive beam forming algorithm. MVDR algorithm can be adaptive so that the array output in the desired direction, the minimum power at the same time SINR than the maximum. Will be applied to the spatial wavenumber spectrum estimation can greatly improve the resolution and noise suppression performance. On the basis of in-depth analysis of MVDR algorithm principle, the results of computer simulation and the sea trials data processing, analysis of MVDR algorithm in high-resolution spatial wave number spectral estimation performance for applications. By comparison before and after the diagonal loading of the data processing results, and improve the effectiveness of MVDR analysis of diagonal loading.
The purpose of this subject is the system currently used in the field of adaptive signal processing, a variety of diagonal loading methods, to study various loading amount of diagonal loading (loading level), calculation methods and a variety of diagonal loading method of characteristics and performance, the conclusion is given.
Keywords: Beam-forming ；Spatial Wave-number spectral estimation；MVDR； Diagonal loading
目 录
1． 引言 2
2． MVDR自适应波束形成算法原理 2
2．1 MVDR权矢量 2
2．2 协方差矩阵估计 4
2．3 MVDR性能分析 5
2．4 MVDR算法在空间波数谱估计中的应用 6
仿真实验1 6
仿真实验2 7
应用实例1 7
3． MVDR性能改善 9
3．1 快拍数不足对MVDR算法的影响 9
仿真实验3 11
3．2 对角加载 12
仿真实验4 13
3．3 替代的误差分析 14
仿真实验5 15
3．4 对角加载应用实例 16
应用实例2 16
总结 19
参考文献 20
