Design and experimental research on shallow water volume reverberation signal acquisition system

Volume reverberation is the main interference of active sonar in shallow coastal waters. This greatly limits the sonar's working range and the performance of parameter estimation. A lot of research on the properties of deep scattering layer, sea surface reverberation, sea bottom reverberation has been done. However, the research on volume reverberation at 10 to 40 kHz in shallow coastal waters is only a little. It is difficult to collect shallow water volume reverberation signal by conventional underwater acoustic signal acquisition equipments with an electrical switch, due to circuit obstruction. Therefore, based on the characteristic of volume reverberation, a signal acquisition system was designed. The control core was made up of Field Programmable Gate Array (FPGA). The signal acquisition system was tested in shallow coastal waters. The law of volume backscattering intensity with temperature, salinity, the concentration of suspended sediment particles, and frequency is summarized. The results demonstrate that the volume backscattering intensity may be changed by 30 dB, due to the concentration change of suspended sediment particles.1