Characteristics Analysis And Application Research Of Surface Target Radiated Noise

The radiated noise from surface targets is an important source of information for passive acoustic detection of targets.The analysis of the acoustic characteristics of radiated noise and its propagation in the ocean has been a hot topic in the field of underwater acoustics.The noise sources that contribute to surface target radiated noise are numerous and vary in their mechanisms of noise generation,resulting in highly complex acoustic characteristics.Moreover,different ships exhibit different acoustic characteristics depending on their navigational status,which have certain time-variation and randomness.In addition,the dispersion of normal waves and the multipath characteristics of ocean waveguides also affect the acoustic propagation of radiated noise.Considering the above factors,extracting stable and significant acoustic features of radiated noise from received signals is the key challenge in passive detection of underwater targets.Therefore,it is necessary to study the acoustic characteristics of surface target radiated noise and its propagation in the ocean.The main research contents of this paper are as follows:(1)Based on the mechanisms of each noise component of surface target radiated noise,the acoustic characteristics of each noise component in the time and frequency domains were realized.On this basis,a model and numerical simulation of surface target radiated noise were established.By comparing the measured data and simulation results,it is verified that the radiated noise signal obtained by simulating the mathematical model of ship radiated noise based on this paper can meet the frequency domain sound characteristics of the real water surface target radiated noise that is of concern.(2)Based on normal mode theory,the propagation of line spectrum noise and continuous spectrum noise in surface target radiated noise in shallow water waveguides were studied.Through numerical simulation,the effects of dispersion and multipath characteristics of the waveguide on target azimuth and elevation angle estimation are analyzed.(3)In view of the influence of dispersion characteristics on target passive detection,a numerical simulation of a dispersion compensation method based on waveguide invariants was conducted for various shallow water waveguide environments and frequency ranges.The results show that the frequency dispersion compensation effect of the transformation method depends on the variation of the waveguide invariants within the processing frequency range.Finally,numerical simulation studies are carried out on the target azimuth and elevation angle estimation based on dispersion cancellation,verifying the feasibility of applying the dispersion cancellation transformation method to improve the estimation performance of the channel multipath structure.