Research On Target Classification Technology Through A Single Vector Hydrophone

Aiming at the problem of classification of surface / underwater targets under lowfrequency conditions of shallow waveguides,this paper studies the target classification method based on the modal scintillation index and the modified scintillation index.Under the premise that the acoustic information of the marine environment is accurate,generally it can obtain relatively good quantitative identification results.In order to reduce the impact of environmental mismatched target recognition,based on the data-based matching field localization theory,this paper proposes a target classification method based on the fused modal flicker index.The complex sound pressure under the conditions of shallow-waveguides can be expressed by the zero-order Hankel transform of the Green's function,especially in the far-field condition,it can be approximated as the Fourier transform.According to the above characteristics,the modal wavenumber spectrum of the target is estimated through the synthetic aperture generated by the target motion.The modal wavenumber spectrum corresponds to the depth-dependent modal excitation function,and the sum of the modal excitation functions is used to construct the Fused modified modal scintillation index(FMSI).The effects of acoustic channel,substrate characteristics,frequency and receiving fluctuation amplitude on FMSI are analyzed through numerical simulation,and its robustness is given.Finally,the target classification is performed through the processing of experimental data(surface ship and deterministic sound source).The results show that the method has good performance and development potential in terms of deep classification,and has certain reference value for future research.Aiming at the problem of sound source depth estimation at low frequency in shallow sea waveguides,this paper proposes a method based on data to estimate the depth of the source using a differential matching mode.It relies on Hankel transform to estimate the modal wave number spectrum to extract source depth information.For actual data,first use FFT to process each piece of data to obtain its sound pressure field.The sound pressure field is controlled and the wave number is formed according to the synthetic aperture generated by the source motion to generate a modal wave number difference spectrum.A fuzzy function that calculates the sound source depth using the selected wave number difference spectral peaks is used to estimate the source depth.The numerical simulation results show that in the two cases of radial or nonradial motion of the sound source relative to the receiving hydrophone,using the data-based differential matching mode to estimate the source depth has achieved relatively good results.The spectral suitability of the method under various low-frequency conditions is analyzed.Finally,the sound source depth estimation is performed through experimental data.The results show that the method has good performance and development potential in terms of depth classification,and has certain reference value for future research.