【作者】 鲍雪山；

【导师】 徐新盛；

【作者基本信息】 哈尔滨工程大学 ， 通信与信息系统， 2007， 博士

【摘要】 随着社会的发展,无论民用领域还是军事领域,噪声控制问题正越来越受到重视。噪声控制技术也取得了长足进步,但是仍有许多问题有待解决。信号存在情况下的有源噪声控制(ANC)技术就是一个新近被提出的重要问题。本文着重进行了以下几个方面的研究:信号存在情况下的“具有信噪比提升能力的ANC技术”理论研究;为了解决降噪和信号失真问题,进行的新型算法和结构研究;实际声场中常见的信道在线建模问题研究;以及工程应用将要面临的互耦合多通道系统研究。传统ANC系统的待抵消噪声中不包含有用信号,噪声希望被完全抵消;但在某些特殊的应用场合里,特别是对引入新的声场极度敏感的舰艇环境,待抵消噪声(主要是舰艇自噪声)中包含有信号(目标信号),噪声被降低的同时,信号希望被保留,这就是“具有信噪比提升能力的ANC系统”。本文构建了这种系统的物理模型,分析了针对该系统的“噪声处理增益(这里特指降噪能力)”、“系统处理增益(这里特指信噪比提升能力)”、“信号失真度”和“信号失真测度”概念,完善了理论体系,完成了仿真实验。研究表明:该类系统能够降低噪声,但是信号会失真,影响该系统性能的最主要因素是参考输入端信噪比的大小。也就是说,只要合理设计参考噪声的拾取方式,该系统能够用于抵消干扰噪声,在获得较高的系统增益同时,保持较低的信号失真程度。根据上述理论,本文提出了几种新型系统用于解决降噪和信号失真问题。这些系统包括:利用独立成份分析方法对参考输入进行预处理的ANC系统,以及利用抗串扰自适应抵消器对参考输入进行预处理的ANC系统。完成了理论分析、仿真实验和海试数据的处理,其结果表明:这些预处理技术降低了信号和噪声之间的干扰,根据“具有信噪比提升能力的ANC系统”性能评价指标体系,这些新型系统具有现有系统所没有的优良性能。针对现有的时域、频域和小波分解ANC系统不具备任意的时间、频率(高频细节和低频轮廓)分辨能力的弊端,本文提出了基于小波包分解的ANC系统,推导了滤波-X(FX)结构下的LMS算法和RLS算法。完成了理论分析、仿真实验和海试数据的处理,结果表明该系统具有先天的技术优势和现有系统所不具备的良好性能。真实声信道的存在是ANC技术和自适应降噪技术的本质区别之一。本文对信道在线建模ANC技术进行了深入的研究,指出了现有技术存在的问题:建模和控制之间相互干扰,以及次级信道对用于建模的激励源的响应增大了系统收敛后的声场能量。本文提出了三种新的信道在线建模ANC系统:改进型FX结构次级通道在线建模ANC系统、基于峰值预滤波的次级通道在线建模ANC系统、以及考虑参考输入信道的同步方程ANC系统。理论分析、仿真实验和海试数据处理结果表明:这些系统各具优势,在一定程度上能够较好地解决上述两个问题。多通道ANC系统是区域降噪的必然之选,本文对多通道“耦合”问题进行了研究。并且以单通道改进型FX结构ANC系统为例,对其进行了多通道推广,给出了多通道FXRLS算法表达式,完成了理论分析和计算机仿真实验。结果表明该多通道系统具有良好的降噪性能。更多还原

【Abstract】 With the development of society, the subjects of noise control have attracted more and more attention in both civil and military fields. Great progresses have been made up till now, however there are still many problems remaining to be solved. The technique of active noise control (ANC) in the presence of useful signals is just an important subject which arises recently.In this dissertation, some aspects of the subject have been studied: theories of new ANC technique with SNR (Signal-to-Noise Ratio) processing gain in the environments of noise and signals; algorithms and systems for noise cancellation while retaining signals undisturbed; methods of online path modeling encountered in real sound field; and cross-coupled multi-channel ANC systems for practical applications and acoustic simulation experiments.The noise is always hoped to be cancelled completely in the conventional ANC system because it does not have any useful information in most cases. But in some special application environments, such as the naval ships where it is extremely sensitive to newly introduced sound field, and the noise to be cancelled (mostly, the ship’s self-noise) contains useful signals (target signals). The ANC system is expected to have the highest level of noise reduction while to retain the signal energy in the greatest extent. This kind of system is defined as ANC system with SNR processing gain. In the dissertation, the system physical model was built; concepts of "noise processing gain", "SNR processing gain", "signal distortion" and "signal distortion measurement" for the system were introduced and mathematically defined; a relatively complete theoretical system was established; and the computer simulation tests had been conducted as well. The results show that the newly developed system based on classical ANC principles works but the signal will be distorted in some degree, and the most important factor that influences the system performance is the SNR of reference input. In other words, if the reference input is designed to be picked up the properly, the system can used to cancel the interference noise, obtaining great SNR processing gain while retaining a low level signal distortion.Based on the above theories, several novel systems are proposed to solve the problems concerning noise cancellation and signal distortion. These systems include two kinds of ANC systems with pretreated reference input using independent component analysis (ICA) in time and frequency domains, respectively and an ANC system with pretreated reference input using crosstalk resistant adaptive noise canceller (CRANC). Theoretical analysis, computer simulation tests and processing of raw data collected from sea run tests are accomplished. The results show that these preprocessing techniques can reduce the cross interferences between signal and noise. Examined by the performance indexes of the ANC system with SNR processing gain, these new systems have better capabilities than existing systems.Aiming at the lacking capability of optional time and frequency (high frequency details and low frequency contour) resolution for existing time domain, frequency domain and wavelet decomposing domain ANC systems, a new system structure is proposed to solve this problem. This dissertation proposed a new filtered-X (FX) ANC system based on wavelet packet decomposing (WPD). LMS and RLS algorithms are derived under the filtered-X (FX) structure. Theoretical analysis, computer simulation tests and processing of real data collected from sea run tests are accomplished. Results show that the proposed scheme has inherent technical advantages and favorable performances which the conventional ANC system does not have.The existing of real sound path is one of the essential differences between ANC and adaptive noise cancellation. The online path modeling technique of ANC system has been studied intensively in this dissertation. Disadvantages of current techniques are that there exists disturbance between modeling filter and control filter, and that the exciting source for online secondary path modeling will increase the energy of sound field after system convergence Three new online path modeling ANC systems are proposed in this dissertation: modified FX structure online secondary path modeling ANC system, online secondary path modeling ANC system based on peak prefiltering technique, and ANC system of simultaneous equations which considers the existing of reference input path. The theoretic analysis, computer simulation tests and processing of real data collected from sea run tests are carried out. The results show that these systems have advantages on their own, and can be used to solve the two problems mentioned above in a certain extent.Multi-channel ANC system is the inevitable choice for regional noise cancellation. The problem of cross-couple of multi-channel has been studied in this dissertation. As an example, the modified FX structure is generalized into multi-channel ANC system. Algorithm of multi-channel FXRLS is developed. Theoretical analysis and computer simulation tests show that the multi-channel ANC system has good capabilities.更多还原