Research On Deep Sea Targets Passive Positioning Technology With Multiple Vertical Arrays

Underwater acoustics localization is an important part of marine science and has been a hot spot in the study of underwater acoustics workers in recent decades.Underwater acoustic positioning could be divided into active and passive mode.A known source is used in the former mode,whose performance is related closely to the target scattering,but with more prior knowledge.Noise radiated by the target is used in the latter mode.Results of both modes are influenced heavily by the underwater acoustic channel.In this thesis,methods of passive positioning are studied utilizing the knowledge of deep sea channel and data collected by spatially distributed multi-vertical arrays.Firstly,according to the characteristics of sound wave propagation in the deep sea,the single vertical array matching field localization technology is studied.The matching field positioning method can be used to estimate the horizontal distance and depth coordinates of the target sound source,but is sensitive to environmental parameters.In this thesis,the method of deep sea matching field localization is given,and the performance of the matching field is simulated.The evaluation criteria of matching field positioning are given.Secondly,based on the deep sea channel effect,the two-dimensional estimation method of moving target depth distance based on array beamforming is studied.Under the condition of deep sea channel,combined with the multi-path effect caused by the reflection of the sea surface acoustic signal in ray acoustics,the positional relationship between the direct acoustic wave received by the vertical array and the multi-path reflected sound wave relative to the fixed sound source target is analyzed.The sound source target signal received by the single vertical line array is used for beamforming,and the orientation information of the sound source target is obtained.Estimating the horizontal distance according to the target azimuth information and combining the sound source depth information contained in the output sequence of the vertical array beamforming to solve the depth of the sound source to obtain the position information of the fixed sound source target.Then,in the deep sea multi-path conditions,the depth of the moving sound source target close to the sea surface is estimated.On the basis of deep-sea multi-path,combined with the theory of ray and the principle of specular reflection,firstly through the beamforming of the vertical array,the change of the vertical angle of the moving target and the output power of the beamforming are obtained for a period of time.By performing Fourier transform on the beamforming output power and integrating along the vertical angle change path,therelationship between the sound source depth and the output power is obtained,and then the depth information of the moving target is obtained.Finally,based on the passive positioning method based on single vertical array,the multiple vertical arrays joint positioning method is studied.Firstly,beamforming is performed on each vertical array to distinguish between direct waves and sea surface reflected waves in multi-path signals,thereby improving the accuracy of delay estimation between sound source and vertical array.The multi-vertical inter-beam beam output correlation processing is used to overcome the mutual interference between multiple targets.Finally,the long-baseline hyperbolic localization is obtained by using the delay difference estimation results between the arrays to obtain the target position,and the corresponding multiple vertical arrays combined with passive positioning performance.