Research Of Seafloor Scattering Model And Statistical Characteristic Of Multibeam Reverberation Signal

Many researches in the field of seabed mineral resources, marine geology, underwater engineering geology, marine fishery, underwater communication are necessary to adopt effective tools and methods to comprehensively characterize the seafloor information. Multibeam bathymetric system as a wide-coverage and high-precision water depth measurement device, can be widely applied in the field of the water depth measurement, the measurement of the seafloor topography, sediment classification and other fields. Seafloor backscatter strength and signal envelope probability distribution have played an important role in detecting seafloor acoustic characteristics by multibeam bathymetric system. Therefore, this paper researches the two characteristic parameters from the aspects of theoretical and experimental, and mainly to complete the following:(1) Introduce Jackson scattering model to research the high-frequency acoustic scattering problem, and by numerical simulation, analysis the relationship between backscattering strength and different factors such grazing angle, sediment type, frequency, sound velocity, seabed environment acoustic parameters.(2) Analyze two reverberation envelope probability distribution models (Rayleigh distribution model and K distribution model) by theoretical, and analysis K distribution parameter estimation method which used in this paper and its estimated performance. Focus on the completion of multibeam seafloor reverberation simulation so that each channel received signal envelope obey K distribution, and use the physical meaning of specific Jackson scattering model to calculate the contribution of backscattering strength. Finally, examine the performance of simulated signal from the four aspects of the waveform, envelope probability density distribution, temporal correlation and spectrum characteristics.(3) Process the simulation of multibeam reverberation signal by beam forming method and get backscatter signals from multiple angles. After that, estimate the probability distribution of the envelope of these signals and analyze the relationship between the incidence angle, the number of scatterers and distribution parameters. The results from the treatment are that the signal envelope distribution characteristics similar to the K distribution, and the distribution parameters changes with the incidence angle and the number of scatterers.(4) Introduce extraction method of backscattering strength data from the multibeam bathymetric system data, and extract backscattering strength changing with angle from the experimental data, and compare it with the theoretical model; Process the experimental data by multiple beam forming method and estimate that the probability distribution of the beam direction of data and analyze the incidence angle dependence of distribution parameters. The results from the treatment are that the experiment data distribution characteristics similar to the K distribution, and the distribution parameters change with the incidence angle.