利用船舶噪声的自相关与倒谱联合估计多径时延

对2007南海试验中多个航路船舶噪声的自相关和倒谱特征进行了分析研究,结果发现:近距离处倒谱图中的时延峰曲线消失、自相关相对倒谱有更高的时延峰检测信干比。类似现象此前未见报道,说明在一定条件下采用单一自相关法或倒谱法均难于连续检测时延峰。为解决这一问题,首先应用射线声学理论结合数值仿真,解释了该试验现象的产生与“随距离减小,倒谱和自相关的时延峰绝对幅度分别减小和增大”的性质有关,进而提出了一种利用船舶噪声的自相关和倒谱联合估计多径时延的方法。海试数据处理结果表明:本文方法能够稳健地跟踪多径时延峰,有效地弥补传统单一自相关法和倒谱法的不足,对解决多径时延的连续估计问题有明显效果。 

Multipath time-delay estimation using auto-correlation and cepstrum of ship-radiated noise

The characteristics of auto-correlation and cepstrum of ship-radiated noise observed during 2007 South Sea Experiment are analyzed in this paper.It is found that the multipath time-delay peaks of the cepstrum couldn't be observed in the near range,and as well the auto-correlation method has relative higher signal-to-interference ratio to detect time-delay peak than the cepstrum method.The similar experimental results have never been reported,and show that it is difficult to track the time-delay peak continuously using each one of those traditional method above.Base on the ray acoustics theory and the numerical simulation,these results presented in this paper can be explained by the fact that the absolute amplitudes of time-delay peak of the auto-correlation and that of the cepstrum increase and decrease with a decreasing range,respectively.Moreover,a hybrid multipath time-delay estimation technique combining the auto-correlation method with the cepstrum method is proposed to solve the problem of the continuous tracking of time-delay peak.Finally,the processing results of sea trial data demonstrate the effectiveness and robustness of our proposed method.