宽带水声信号传播损失分析

根据能量关系推导了宽带声呐方程，研究了宽带水声信号的传播损失。宽带传播损失中的吸收损失是信号带宽内各个频率吸收损失的加权平均值。由于权值是指数衰减的，因此低频成分起的作用更大。在相同的距离和中心频率上，带宽越宽，则低频成分所起的作用越大，总的传播损失反而越小。同时，与窄带分析方法对比可以看到，采用窄带方法计算宽带信号的传播损失会引入较大的误差，距离、带宽越大，误差越大。宽带传播损失的分析对于不同作用距离上信号带宽的选择，以及宽带声呐性能的预测具有指导意义。

Analysis of the propagation loss of wideband underwater sound signal

Based on energy relations, this paper arrives at the equation of wide-band sonar and researches on the propagation loss of wide-band underwater sound signal. The absorbing loss in wide-band transmission is the weighted average value of absorbing losses of every frequency in the bandwidth of the signal. Since the weighted value is attenuated exponentially, those components from low frequency are therefore more important. At the time when keeping the distance and the center frequency constant, the wider the band is, the more weights the component from low frequency takes, and, as a result, the less propagation loss it has. At the same time while comparing to narrow-band analysis, we find out that calculating the propagation loss of wide-band by using the method of narrow-band analysis would bring in big error, and it gets bigger when distance and bandwidth go up. To sum up, the analysis of propagation loss of wide-band acts as a guide in selecting bandwidth based on different distances and forecasting the performance of wide-band sonar.