Research On Targeting Detection Method In Shallow Sea Based On TRM Technology

Underwater acoustic technology about underwater acoustic positioning technology is very important and the basic question.At present the various forms of energy and transmission medium are known by people,sound wave propagation in seawater with the best performance,the sound field is a physical field which spread the farthest underwater.Whether light signals or electromagnetic waves in turbid and complex marine environment,their propagation attenuation are very large,and the propagation distance in seawater medium is also very limited.Because of the role of targeting technology,underwater acoustic positioning technology is a key role in the acoustic signal technology research.Through collected acoustic signal autocorrelation,target location technology in a traditional autocorrelation algorithm are research.According to the features of the autocorrelation the signal time difference value is extracted to achieve the target.However,the false information after autocorrelation waveform is produce by the specific environment and shallow sea of multiplicity effect in the shallow sea water,it is unable to positioning.So the TRM technology for the signal focusing is put forward to get turn the related waveform,then achieve the positioning.Single and array type are included by TRM technology.Signal energy focus can be realized in spherical wave sound field array by type TRM technology,and single hydrophone is unable to realize.But signal energy focus can be realized by single hydrophone TRM applications in shallow sea waters which is combined with water acoustic feature.Single hydrophone TRM technology has advantages of better concealment and save resources,so signal energy focusing is adopt to realize target orientation by single hydrophone TRM technology for in shallow sea waters in this paper.First of all,a mathematical model on single hydrophone TRM technology are established by ray theory.Underwater acoustic signal acquisition system is Designed and the lake experiments was used to simulate shallow water acoustic environment.Suitable acoustic signal transducer,acquisition card and signal conditioning and upper compute are selected as main devices,and upper compute equipped with LabVIEW application software.Because of the complex experimental environment,all kinds of interference will be contained in signal acquisition,the pretreatment of the underwateracoustic signal is designed.Secondly,compared to the collected signals before and after by the application of the TRM technology to verify the TRM technology feasibility and advantage.The time difference value of the direct wave and only occur once the reflection wave is determined by combined the traditional correlation function algorithm.The target location of the horizontal distance and depth measurement are achieved by using the virtual source method which combined with the mathematical model of single hydrophone.Also the azimuth of target location is measured by linear disposal localization algorithm.Finally target location is achieved.The traditional algorithms of shallow water target localization accuracy is improved through the experimental data verified,this method prove feasible.