Research On Multi-target Positioning Technology Of Ultra Short Baseline Positioning System

With the rapid development of marine economy,underwater acoustic positioning system plays an increasingly important role in marine engineering.Among them,the USBL(ultra-short base line)positioning system has the advantages of small size,light weight and simple operation,which has been widely used.In order to meet the needs of underwater positioning system in different occasions,the positioning target gradually develops from traditional single target positioning to multi-target positioning.The development and research of underwater multi-target positioning technology has practical engineering application value.In this paper,the multi-target positioning algorithm based on the USBL system is studied according to different positioning signal forms,which has a positive significance for expanding the application of underwater acoustic positioning system.The research of narrowband signal multi-target positioning technology is implemented.Firstly,by studying the performance of LMS algorithm adaptive phase shift estimator,the improved LMS algorithm adaptive phase shift estimator and RLS algorithm adaptive phase shift estimator are proposed to improve the convergence speed and steady-state accuracy.And the effects of parameters on its convergence characteristics and tracking ability are analyzed respectively.Then,the performance of the two improved adaptive estimators is verified by comparing the experimental data.Finally,the multi-target positioning technology is studied based on the multi-channel parallel RLS algorithm adaptive phase shift estimator.And the anti-interference ability and multi access ability of the multi-target positioning technology based on narrowband transmission signal are analyzed by numerical simulation.The research of wideband signal multi-target positioning technology is also implemented.Firstly,the quadratic correlation method and polynomial interpolation algorithm are introduced to improve the accuracy of time delay estimation.The application of frequency hopping signal and FH-OFDM signal in multi-target location is studied respectively.Then,the number of sequence codes and Hamming correlation of m-sequence,balanced gold sequence and Costas sequence are analyzed.It is proved that these three sequences are suitable for underwater multi-target positioning.Finally,the simulation of multi-target location based on frequency hopping signal and FHOFDM signal is carried out.The anti-ISI ability and multi access capacity of the USBL system of broadband signal are analyzed.And the feasibility of multi-target location based on the two transmitted signals is verified.In this paper,the multi-target positioning technology of different transmission signal forms is studied respectively.The results show that the USBL multi-target positioning system based on narrow-band signal has the advantages of small calculation,simple structure and easy engineering realization.while the USBL multitarget positioning system based on broad-band signal has lower requirements on SNR(signal-to-noise ratio),and has lower positioning accuracy and multi access capacity.With the increase of the number of targets,the advantages of broadband positioning system are more obvious.In the actual project,according to different needs,the appropriate multi-target positioning system can be selected to complete the task of underwater positioning.