浅水区水下爆炸直达声辨识与时频分析

为有效截取直达声分量以分析真实的水下爆炸声源特性，提出一种利用局部相关峰进行直达信号辨识的标记算法，并建立起算法结果的评价函数，然后结合浅水区水下爆炸实验，对比射线理论计算所得直达声分量的数目，初步验证了算法合理性，最后对所捕获的最优直达声片段(宽度约1.8 ms)进行希尔伯特-黄变换(HHT)，分析频谱特性。结果表明：直达声压级时间序列具有良好的自相关性，且在近程条件下，其相对排列特征能近似保持稳定；该算法可以获得较高的局部相关峰，使得直达声片段能够被清晰地标记出来，尤其是在超近程条件下，相关峰可达0.9以上；爆炸声源的主频带稳定在0~10 kHz，且峰值频率约1 kHz，但是当传播距离较远时，其形状会明显受到声速剖面影响。

Identification and time-frequency analysis of direct components from the underwater explosion in the shallow water

For obtaining direct sound component effectively to analyze real characteristics of the underwater explosion source, a marking algorithm is proposed, which utilizes the local correlation peak to identify the direct sound. The evaluation function for the algorithm result is established. Based on underwater explosion experiments in the shallow water, the reasonability of this algorithm is initially verified by comparing with results through the ray theory, and further the frequency spectrum analysis is performed on the optimal direct sound interval(width about 1.8 ms) acquired by this algorithm through Hilbert-Huang Transform(HHT). The results indicate that: the sequence of the direct sound pressure level has a high autocorrelation and the corresponding relative array feature can keep stable approximately in the short range; this algorithm can bring good local correlation peaks and identify the direct sound components clearly, especially in the very short propagation range, with the correlation peaks even over 0.9; the main frequency band of the used explosion source is stable around 0-10 kHz, with the peak frequency of 1 kHz approximately, but when the propagation range is relatively longer, the corresponding spectrum profile will be influenced by the sound speed distribution significantly.