Research On Target Localization And Sonar Deployment Based On Sound Field Characteristics

Underwater target detection is an important part of the marine military,and its main method is sonar detection.With the strategic advancement of development of maritime powers,the detection of underwater targets has become a hot issue in underwater acoustic engineering.This dissertation combines the research of the research group and a large number of marine experimental data to carry out related research on target detection.This dissertation mainly discusses and studies these aspects: acoustic physical field research,localization method research and sonar layout design.The specific research content of this dissertation can be summarized as follows:1.The dissertation proposes and analyzes the depth estimation method based on model calculation.Utilizing sound field reciprocity and deep-sea stable sound field structure,the dissertation proposes a method for depth estimation of sound source at a fixed distance.Firstly,it is necessary to obtain some depths of the stronger signals at the receiving position,and arrange the simulated sound sources at the obtained depths to establish a sound field model.Calculating the distribution of the acoustic signal at the priori distance,the depth of the strongest signal is the estimated depth of original sound source.The dissertation verifies the feasibility of the algorithm by using experimental data,and realizes the depth estimation of the explosion sound sources outside the distances of 48.88 km,52.39 km.2.The dissertation proposes and analyzes the localization method based on multi-path time difference in deep sea.Using the time difference between the direct wave and the surface reflected wave,the dissertation proposes a deep sea localization method based on multi-path time difference.The method matches the actual data and the sound field data to obtain an ambiguity plane,and the peak value represents the target position.The dissertation uses experimental data to achieve the localization of an explosion sound source outside 16.8km to verify the feasibility of the algorithm.The dissertation also analyzes the robustness of the algorithm.The result shows that the algorithm can use only two hydrophones to achieve the target localization with the array aperture as small as 19.2m.3.The dissertation analyzes multiple vertical line array collaborative detection methods,and realized the estimation of the target’s speed and direction.The vertical line array has the ability to locate the target in the distance-depth two-dimensional plane,but cannot estimate the direction in the horizontal plane.Using multiple vertical line arrays for collaborative detection,the target’s direction of motion can be estimated.First,a vertical line array can achieve speed estimation in the continuous detection of moving targets;when two adjacent vertical line arrays detect the target,the classification of the movement can be determined;When the target is detected by the third vertical line array,the direction of motion can be determined.This method can be used for large-area multiple vertical line arrays deployment at sea to improve the detection range and tracking ability of moving targets.4.The concept of incomplete coverage array is proposed.Then the advantages and disadvantages of three typical active and passive sonar coordination methods are analyzed.A sonar deployment based on the cooperative detection of multiple planar extended arrays is proposed,and the optimized method of sonar deployment is analyzed from the perspective of effective area and scalability.Incomplete coverage arrays is proposed which can be divided into interception arrays and surrounding arrays.The former refers to a number of sonar defense lines that are intermittently arranged in a fixed area,and only serves as an early warning;the latter forms an enclosed detection range in the fortified sea area to achieve the purpose of detecting that the blind area is closed in the sea area.The incomplete coverage array is more economical than the traditional full coverage array.The dissertation also analyzes the localization performance and scalability of three types of active and passive sonar combination.The results show that single-source with single-receiver is the best form of expansion,with various extension forms,arbitrary extension range,and relatively free control of blind zone ratio.5.This dissertation analyzes the effects of deep-sea slope and seamounts on transmission loss based on the distance and number of convergence zones,and then some suggestions for sonobuoy deployment are proposed.Using a large number of acoustic survey data collected by the research group in the South China Sea,the dissertation studies the acoustic propagation characteristics of deep-sea slope and seamounts.The dissertation first summarizes some phenomena from the experimental results,mainly based on the influence of terrain on the convergence zone.Then the dissertation uses the Bellhop model to verify the phenomenon and give relevant explanations.The results show that the slope topography makes the period of convergence zone shorter and the energy weaker.When the depth of the sound source is deep,the convergence zone will be widened.In the case of a flat bottom,the first convergence zone will be submerged in the strong bottom reflection signal in the near field.In the case of the slope bottom,the convergence zone will be weak and almost disappear.The influence of seamounts on sound transmission is mainly the interception effect.The analysis results show that changing the depth of the sound source has a good effect on weakening the interception of the seamounts.When the sound source and the receiver are both shallow,the interception of the seamount is more obvious.Based on the analysis of experimental data and the summary of propagation phenomena,the dissertation puts forward relevant suggestions for the deployment of sonobuoys.It is recommended that the sound source(active sonar)be arranged on the outer edge of the slope,with the receiver arranged on the inner edge on the deep-sea slope;when there is a seamount in the sea area,it is recommended to use prior terrain information to determine the location placement in real time,and the deployment depth is usually deeper.