Research On Key Technologies Of Underwater Acoustic Detection Based On Depth Information Processing

The high-frequency radiated noise level of modern advanced quiet submarine has greatly reduced because of the development of stealth technology,low-frequency detection system based on vector hydrophone becomes an effective means for detecting the quiet submarine,but its potential is not digged adequately.If there is a need to identify whether the underwater target is dangerous or just an ordinary underwater vehicle(AUV,etc.),a high-precision detection equipment is needed.Therefore,it is possible to judge the presence or absence of the target and the depth range by the passive detection method based on the vector field,and then to identify the underwater target of interest using the multibeam and sidescan sonar equipment.In this paper,some research work has been done on signal processing based on depth information of vector field and multi-beam-based sounding algorithm.Firstly,the acoustic field modeling of the shallow normal wave method is analyzed,and the velocity field of the particle is obtained by the finite difference method.The correlation between the sound pressure and the particle velocity in the horizontal direction and the vertical direction is analyzed.The acoustic energy flux density,vortex and other characteristics are discussed.The waveguide normal modes form of the vertical array is extracted by the matched mode processing method,and the amplitude matrix is A,an effective iterative method is used to improve the accuracy of the modal decomposition.The depth estimation of sound source is carried out by modal amplitude correlation method.According to the multi-beam sounding principle,the amplitude and phase method are used to deal with the multi-beam data.At large beam angle,the SNR is low and the beam width is wide,it is suitable to use the phase method based on split aperture to estimate the zero crossing time.At small beam angle the SNR is high and the beam spread is short,which is suitable for DOA estimation by amplitude method.The broadband signal is used in the multi-beam sounding technology and is compared with the narrow-band sounding performance.After using the matched filter,the broadband signal can obtain a larger SNR gain.Then,aeffective waveform is designed to help reduce the error of echo range estimation.