Method And Software Implementation Of Positioning For Buoy-based USBL

This paper is aimed at the ultra-short baseline positioning algorithm of a long baseline(LBL)and ultra-short baseline(USBL)combination positioning system.It discusses two key technology methods of the algorithm,unwrapping phase ambiguity and an expert system for selecting direct sounds.Then the positioning algorithm and necessary function are implemented in the software platform.It can track and locate the horizontal position of underwater moving targets.Finally,the correctness and reliability of the software are verified by the lake test.Firstly,this paper introduces the characteristics of the basic ternary array positioning principle and the cross array positioning principle of ultra-short baseline.And the method of transforming coordinate of targets from array coordinate to geodetic coordinate is introduced.Furthermore,the error source and accuracies are analyzed and simulation results are given.Finally,the advantages of the combined positioning system compared with single long baseline positioning system are simulated and analyzed.For high frequency signal,this paper presents an algorithm based on the maximum a posteriori(MAP).Through the simulation and analysis,this algorithm won't be influenced by the signal frequency.The paper shows the simulation results and the final formation of this system.Due to the multipath effect of underwater acoustic channel,the hydrophones receive signals of both direct sounds and multipath reflected sounds.The function of expert system is to select direct sounds correctly and eliminate reflected sounds.The paper discusses the basic principle and series of criteria of the expert system.Criteria are used to evaluate the quality of each sound and select the best quality sound as the direct sound.And the validity of the expert system is verified by the test data.The ultra-short baseline positioning software is developed on QT Creator environment.The functional requirements of the software are analyzed,and the overall structure frame is designed.Then,according to the modular design idea,the design and implementation of each functional module are given.It is mainly composed of location resolution module,displaying and tracking module and file management module,which make the software have a series of complete functions.Finally,the results of the lake test are shown.The validity of the algorithm is proved and the function and stability of the software are verified.