【作者】 王杰；

【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， 2004， 博士

【摘要】 潜艇自噪声是被动声纳系统的主要干扰。它使声纳接收端的输入信噪比降低,导致被动声纳的有效作用距离相应减小。因此,降低潜艇的自噪声具有很重要的意义。潜艇降噪是一项系统工程,不但需要巨额投入,还有一系列技术问题尚待取得突破,一时还无法从根本上解决。所以,研究潜艇自噪声的自适应有源抵消技术是十分必要的,具有实际应用价值。本文研究使用声学方法在降低潜艇自噪声的同时保留目标信号的自适应噪声抵消技术。与传统的有源降噪技术相比,技术上有创新性,难度更大。 自适应有源噪声抵消(AANC)技术基于由初级声源产生的声场与次级声源产生的声场相消干涉原理。次级声源的输出可以由控制器控制,这个控制器一般是自适应滤波器。自适应有源噪声抵消系统的核心是自适应滤波器结构和算法。 参考输入中信号分量对自适应有源噪声抵消系统性能影响很大。本文对参考信号中信号分量对AANC系统性能的影响进行了详细的分析,得到自适应滤波器解无约束的条件下,AANC系统输出端信噪比、信号失真度及噪声分量功率谱的计算式,并通过引入模平方相干函数提出衡量AANC系统处理增益的评估方法。 线谱噪声主要集中在自噪声的低频段。本文提出了一种采用切比雪夫多项式的直接并联型结构线谱噪声多通道有源陷波器,并且与直接型结构和并联型结构有源抵消器进行了比较。采用切比雪夫多项式在一定程度上保证了可靠的参考输入,采用直接并联型结构增大了参考输入中各谐波分量之间的频率间隔,提高了收敛速度。同时,本文提出了一种采用单位脉冲串的多通道自适应有源噪声抵消器,将这种有源噪声抵消器和Delayed-X LMS算法相结合,可以大大的减小运算量,并且也可以保证良好的收敛特性。 连续谱噪声属于宽带噪声。本文首先介绍了时域多通道滤波—X最小二乘(MFXRLS)算法,然后重点提出了一种基于线性卷积的频域多通道滤波—X最小二乘(MLFFXRLS)算法。通过理论分析和计算机仿真可以看出,MLFFXRLS更多还原

【Abstract】 Submarine noise is the main interference of passive sonar system, which decreases the SNR at the input of the passive sonar, resulting in the deduction of sonar ranging. Therefore, reduction of submarine noise is of great importance. The reduction of submarine noise is a systematic project, requiring enormous financial support as well as series of techniques which have not yet been resolved fundamentally up till now so that researches on the techniques of adaptive active submarine noise canceling is meaningful and valuable for practical application. Applying the acoustical principles, our research subject is to find out a new adaptive active noise canceling technique, which will retain the signal energy during the noise canceling process. This technique is creative and much more difficult compared with conventional active adaptive noise canceling.AANC(Adaptive Active Noise Cancellation) works on the principle of destructive interference between the sound fields generated by the original "primary" sound source and that due to other "secondary" sources, whose acoustic outputs can be controlled by controllers, which are usually adaptive filters. The key is the configuration of adaptive filters and the corresponding algorithm in AANC systems.It’s great for the effect of the signal components in the reference input on the performance of the AANC systems. In this paper, the effect of the signal components combined with the reference noises on the performance of the AANC systems has been studied comprehensively. Mathematical expressions of the signal-to-noise density ratio, signal distortion and noise power spectrum at the adaptive active noise canceller output have been derived under the condition of no constraints for the adaptive solution. By introducing Modular Squared Coherence(MSC) function to the AANC systems, the method for evaluating the processing gain of the AANC systems is proposed in the paper.The line noise is a primary low frequency component of self-noise in submarines. In this paper, a hybrid active periodic noise canceller based on Chebyshev Polynomials has been introduced, and it has been compared with the direct form and the parallel form. Using chebyshev polynomials assures reliable reference inputs to a certain extent. The frequency difference between any two successive sinusoidal components is effectively increased in the hybrid form, as compared to the direct implementation technique. The rate of convergence of each adaptive filter can be significantly improved. In this paper, an AANC using a pulse train has been introduced to reduce the line interference. It has been shown that the total computational cost decreases if the AANC is combined with the Delayed-X LMS algorithm, and the excellent convergence performance has been obtained.The continuous power spectrum noise is wideband noise. First, the multi-channel filtered-x recursive-least-squares(MFXRLS) algorithms are introduced in time domain in this paper. Secondly, the frequency domain multi-channel filtered-X recursive least squares based on linear convolution(MLFFXRLS) algorithm has been proposed. It can be seen from the theoretical analysis and computer simulations that the MLFFXRLS algorithm will be have a much lower computational load than the MFXRLS algorithm, and the MLFFXRLS algorithm will be have a lower computational load than the MFXLMS algorithm for large channels numbers. In this paper, a delayless subband multi-channel system for active broadband self-noise canceling is also introduced, which has computational and convergence speed advantages comparable to a conventional subband design but without introducing any delay in the cancellation path.Finally, we analyze the real data using the proposed algorithms in the paper. In the case of uncorrelated signal and noise, whose bandwidths are both 2kHz, it can be shown from the processing that the adaptive processing gain of 21 dB was obtained, applying the MLFFXRLS algorithm, under the conditions of 2 control actuators, 2 error sensors and the perfect transfer functions of the primary paths and secondary paths to a certain extent if SNRis lower than -45dB in the reference input. The results validate the effectiveness of the proposed algorithms in the practice.更多还原