Research On A Deep Sea Ultra Short Baseline Location Algorithm Based On UWB Underwater Acoustic Signal

This paper introduces the similarities and differences between UWB underwater acoustic signal and traditional RF signal in terms of bandwidth,signal-to-noise ratio,communication distance,time-domain resolution,positioning accuracy,etc.Three different underwater acoustic positioning systems,USBL positioning,SBL positioning and LBL positioning,and their advantages and disadvantages are introduced respectively.The main structure of the transceiver of the ultra short baseline underwater acoustic posi tioning system and the principle of its positioning mode are emphatically analyzed.The law of sound velocity in sea water is analyzed from the main influencing factors of sea water temperature T,sea water static pressure P and salinity S.Based on Snell's law,the sound velocity profile of negative gradient deep-sea positive gradient in shallow water is analyzed,and the shape of deep-sea sound curve is obtained.The influence of water flow on the acoustic line is analyzed by the acoustic line migration model of uniform medium and the acoustic line migration model of non-uniform medium,and the range of the total offset of the positioning target is obtained.The influence of zero gradient section and constant gradient section on the result of ultra short baseline positioning algorithm is analyzed.The simulation results show that with the decrease of grazing angle,the deep-sea sound line is close to the position of the sea surface from the vertical direction,the horizontal distance of propagation is gradually increased,and the bending degree is gradually increased,and the density degree of the sound line is gradually sparse,and the location blind area that the sound line in the shallow sea cannot be swept is analyzed.Firstly,two iterative approximation algorithms of ultra short baseline positioning,tangent approximation method and tangent arc approximation method,are proposed.The arrival time errors of tangent approximation method and tangent arc approximation method are compared and analyzed.Then,by analyzing and referring to some principles of Kalman filter algorithm,combined with tangent approximation method and tangent approximation method,double tangent joint approximation method is proposed,and the gain formula of double tangent joint is improved by the positive and negative arrival time errors of tangent approximation method and tangent arc approximation method.Finally,the approximation speed of the three iterative approximation algorithms is verified by MATLAB simulation,and it is concluded that the bitangent approximation method has faster convergence speed.