Acoustic Echo Degradation of Small Targets Buried in Sediment: A Theoretical Study

摘要

The behavior of a small target in two representative types of sediment was examined. The two types of sediment considered were a soft silty sediment whose sound velocity is slightly less than that of water and a sandy sediment with a much higher sound velocity. The reduction in the target echo due to the presence of the sediment was quantified as a 'sediment factor'. The sediment factor was examined both qualitatively and quantitatively. Qualitatively, it was found that an acoustic field may be divided into distinct zones. For quantitative results, computer simulations, using the SAFARI full wave mathematical model, were used to obtain numerical estimates of the sediment factor. In general, the sediment factor due to the presence of the sediment was found to be more complicated than expected. The results obtained in this report are based entirely on computer models and they remain to be verified by an experiment. Keywords: Acoustic scattering; Bottom penetration; Buried target detection; Shallow grazing angle; Backscattering. (edc)