应用经验模态分解的拖船噪声信号重构及抵消方法
Empirical mode decomposition applied for tow-ship noise signal reconstruction and cancelling
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摘要: 针对拖船干扰的时空特点,提出了将EMD(Empirical Mode Decomposition)应用于拖船噪声信号重构及抵消的方法。为了解决以往需要人工干预挑选EMD输出的多路IMF分量的缺点,提出了将多路IMF(Intrinsic Mode Function)分量与基元域信号按照线谱与连续谱分别做功率谱相关并以谱相关系数最大为准则的挑选算法。基于逆波束形成的理论,利用挑选后的IMF分量重构基元域信号,并与原始基元域信号谱减后再进行方位估计。拖曳声呐模拟器数据与实际海试数据验证结果表明,本文算法能够提高弱目标空间增益,尤其是对于靠近干扰盲区的弱目标空间增益提高明显,并且对拖船多途角扩展干扰也具有较好的抵消能力。Abstract: According to the characteristic of the tow-ship in temporal and spatial domain,it proposed an interference cancelling method which combined EMD with inverse Beamforming algorithm.For solve the shortcoming that it needs manual intervention to choose the Multi-IMF components which generated by EMD,it proposed a choosing algorithm,in which the chosen IMF component decided by the maximum power spectrum coefficient rule.In the choosing algorithm, the line power spectrum coefficient matrix obtained by the spectrum correlation function between the two line spectrums of Multi-IMF components and array domain signal,and the continue power spectrum matrix could be obtained in the same way.Based on the theory of inverse beamforming,it derived the process of spectrum subtraction between the original and the reconstructed array domain data which obtained by the chosen IMF component.The process of bearing estimation is based on the spectrum subtracted array domain data.The results of the towed sonar simulator and real sea trial data showed that the proposed method could enhance the weak target's spatial gain,especially the spatial gain could be improved significantly when the weak target located in the interference area.It also showed that the proposed method has the capability of cancelling the multipath angle scatter interference.