基于双阵元的宽带相干信源数估计

Estimation of wideband coherent source number based on two-element array

摘要:

不同噪声条件下，宽带相干信源数估计是阵列信号处理中的难点问题。本文针对宽带信号的特点，利用虚拟阵列扩展技术，将宽带信号的不同频率成分虚拟为不同间距的虚拟阵元，通过空间平滑削弱信号之间的相干性。但由于噪声的功率谱非严格平坦，虚拟阵列协方差矩阵的噪声特征值发散程度严重，经典的信息论方法完全失效。本文基于对角加载技术，提出了一种新的加载量，有效地平滑了噪声特征值，减弱了其发散程度，并在此基础上利用比率准则改进了信息论方法，实现了两阵元对多个信源的数目估计。仿真实验表明，改进后的方法在白噪声和色噪声条件下均具有较好的性能，优于盖氏圆方法。

Abstract:

The estimation of wideband coherent sources number with different noises is a challenging problem in array signal processing. Aiming at the characteristics of wideband signals, a novel method is proposed based on two-element array, which employs virtual array extension technique to virtualize the different frequencies of incident signals into varying interval virtual elements. Additionally, the correlation among incident sources can be weakened by spatial smoothing technique. However, the noise eigenvalues of the virtual array covariance matrix is seriously divergent due to the non-strictly flat noise power spectrum, which neutralizes classical information methods. In this paper, a new loading value based on diagonal loading is proposed, which can effectively smooth the noise eigenvalues. Furthermore, the ratio criterion is applied to improve the information methods in this paper. Simulations demonstrate this improved method can achieve better performance than conventional Gerschgorin disk estimator with white and colored noises.