识别与提取简正波的一种简化方法

本文提出了一种识别与提取浅海简正波的简化方法。海上实验时我们利用同一个水听器,在不同深度接收固定距离上的爆炸信号,实验室回放时爆炸声信号经高频(8kHz)与低频(<0.8kHz)带通滤波,并用高频信号作为低频信号时间采样的起点。理论与实验表明,这样得到的不同接收深度的低频信号相当于一个垂直水听器阵接收的结果。对不同接收深度的低频信号分别按简正波本征函数或按本征函数的符号加权相加,较好地分离出前二号简正波。

A SIMPLIFIED METHOD FOR IDENTIFICATION AND EXTRACTION OF NORMAL MODES

A simplified method for filtering normal modes in shallow water has been developed.During the experiment a single hydrophone,placed at different depths,received the explosive signals at a certain distance.In the laboratory the received signals were filtered in octave band centred at a higher frequency (8 kHz) and in 1/3 octave bands centred at several lower frequencies (<800 Hz),and the high-frequency signal was used as the trigger to start sampling the signals at lower frequencies.The theoretical calculation and the experimental results showed that for these lower frequencies the depth dependence of the signals received at different depths by the single hydrophone was similar to that for the case when a vertical hydrophone array was used.And the filtering of the first two modes has been realized by adding up the signals received at different depths with the weighting coefficients determined according to the mode eigenfunctions or their signs at the corresponding depths.