Research On Scattering Feature Of Underwater Partly Filled Target

There are some critical problems in detection of active sonar echoes from underwater small targets,including lack of prior information,uneven sound field distribution at different angles of incidence and mixed ingredients,and these problems increase difficulty of extracting the stable scattering features of underwater targets.Considering environmental interference effect,in order to solve the problem of instability of target echo signals in complex ocean environment,extraction of these features of acoustic scattering echo signals of underwater partial filled targets should be studied.Based on the mechanism and signal characteristics of acoustic scattering components and the structure of acoustic scattering,the underwater sound signal characteristic database is constructed,which provides the foundation for the establishment of underwater target scattering model in order to achieves the recognition of underwater quiet small target by using active sonar.According to research on acoustic scattering,geometric acoustic scattering and elastic acoustic scattering is seriously the aliasing in time and frequency domain.The long-pulse and chirp signals are transmitted by using active sonar.In this paper,the target acoustic scattering components are mapped to single-frequency signal components by applying demodulation process.And these components can be separated by using Gauss Filter.These processing results of simulation and experimental data show that this method can effectively separate target acoustic scattering components.The research shows that the number and type of target scattering components cannot be identified without prior information about target model.A large number of documents show that the spectral structure of acoustic scattering components and elastic scattering components are obviously different.Therefore,in this paper,the center frequency,frequency bandwidth,fractional bandwidth,spectral centroid and spectral flux,these five kinds of spectral features are extracted.The Euclidean metric is used to characterize these features.Finally,the scattering components are classified.The time-delay estimation of the separated geometric acoustic scattering components is processed by using the method of high-resolution spectral estimation.These processing results show that the delay information and timing structure of the geometrical scattering components in the target echoes can effectively obtained by using this method.Aiming at the problem of uneven spatial distribution of the target echo,the target full-angle echo signal is studied and processed.Using the processing flow of this article,the scattering components of the target full-angle echo are separated in order to avoid the aliasing components.The target geometric acoustic scattering time-frequency is estimated by using high-resolution spectral estimation.The spectrum structure of the full-angle elastic echo is obtained,as as to qualitatively determine the target echo in the separation results Effectiveness.The processing results of experimental data show the effectiveness of the proposed method.In this paper,the signal characteristics reflecting the signal scattering characteristics are extracted,and the target geometric acoustic scattering full-angle model and the elastic acoustic scattering angle spectrum feature model are constructed,which are suitable for the actual target detection and provide the technical basis for the underwater target detection...