Influence Of Seafloor Reverberation On Sonar Range

In the research of underwater acoustics,seafloor reverberation has always been a hot topic,which is one of the important interferences of active sonar target detection.In the low signal to mixing ratio(SRR)region,the target echo signal is easily masked by reverberation,which leads to the increase of false alarm rate of sonar.Therefore,it is of great significance to obtain the spatial distribution of reverberation,especially the distribution of signal to mixing ratio,for improving the detection range of active sonar.Although reverberation models have been studied for a long time,due to the complexity of underwater acoustic propagation,the difficulty of obtaining boundary information and the limited computational speed,these models either ignore the influence of complex sound velocity profile on acoustic propagation,or adopt empirical and semi empirical scattering models.Due to the lack of description of scattering physical mechanism,it is difficult to analyze the influence of seabed parameters,such as undulating seabed roughness and medium inhomogeneity,on the reverberation,which is obviously not conducive to the calculation and research of reverberation.In this paper,ray tracing theory(Bellhop core)is used to solve the bending problem of sound propagation with the change of sound speed,and then the scattering model including seabed parameters and interface roughness fluctuation is completed by using the small slope approximation theory.Finally,the reverberation model of monostatic transceiver and bistatic transceiver is completed.After the construction of sound propagation model and reverberation model,through calculating the reverberation of active sonar and sound propagation loss in space,the change of signal margin in sound field is obtained,and the signal to mixing ratio in space is further analyzed.According to the sonar system,the active sonar operating range is evaluated.Generally speaking,the propagation loss we get is the information in frequency domain of a certain point in space,while the reverberation we get is in time domain.In the past,the correspondence between propagation loss and reverberation is directly divided by the distance divided by the sound speed to complete the correspondence between space and time,which is obviously not rigorous enough.In this paper,by observing the arrival structure of the sound line,the arrival time of the sound line contributing the sound energy at a certain point in the field is obtained when calculating the sound propagation loss,which strictly corresponds to the reverberation at the corresponding time,and a more rigorous corresponding relationship is obtained.Finally,the sound propagation model and reverberation model are added into the sonar system to obtain a complete sonar performance prediction system,which is implemented in C language.