两参考输入复滤波NLMS主动噪声控制系统性能分析

The Performance Analysis of Active Noise Control System with Twin-Reference Complex Normalized Filtered-XLMS Algorithm

研究了将主动噪声控制系统应用于舰船的自噪声控制,用来抵消舰船的低频线谱噪声群时,参考输入为两个单频复正弦信号条件下,次级通道对Filtered-XNLMS算法的收敛性能影响。对该问题做了严格的数学分析和仿真试验,最终结果表明:对于本地线谱噪声有源抵消而言,由于次级通道的影响,参考输入的两正弦信号的归一化频率间隔Δf/fs以及反映次级通道幅频特性对不同频率信号的幅度加权程度比例因子α都对系统性能有影响,也就是说,当比值因子α较大时(α>1),系统的收敛性能只是与步长μ有关,与差频Δf的大小无关;当α较小时(α≤1),系统的收敛系统决定于步长μ和主输入的两个正弦波的差频Δf;特别对于α=1情况,系统很快就可以收敛,具有非常好的跟踪性能。

This paper studies the effects of secondary-path to system convergence performance of active noise control （ANC） system that is applied to cancel the self-noise of ships at low frequency linecomponent spectrum. The proposed ANC system is a feedforward system with fihered-x normalized least-mean-squares （FXNLMS） algorithm using two reference inputs composed of single-frequency complex sinusoidal signal respectively. In this paper, the rigorous mathematics analysis and computer simulations are done, the result shows that when an ANC system is applied to suppress the local linecomponent spectrum noise, its performance will be influenced by several factors, such as ratio △f/f, and α that respectively denote the two reference signals＇ normalized frequency separation and the different incremental multiple of the amplitude to the different frequency signals transmitted in the secondary-path. At a word, the system convergence performance is only relative to step size μ for the iterative process but not the frequency separation △f when a is large （ α 〉 1 ） ; the system convergence performance is relative to both step size and frequency separation of the two sinusoidal signals as primary inputs when the α is small （ a ≤ 1 ）. Especially the ANC system can show fast convergence Speed when the ratio α is equal to 1, which makes it possible to obtain good system tracking performance.