Research On Acoustic Focusing Technology Of Semi-circle Array Based On Higher-Order Cumulant

The target location is influenced by ship radiated noise badly. Identification of the targetlocation by ship noise has become the hot spot of underwater acoustic signal processing.When the target distance decreases, and the miniaturization of the base array aperture, thetarget may be in the array near-field range, at the same time, the warning of the near-field andnear-coast port defense are more and more important. so this article’s research and discussionis about the identity of the target in the near field of the base array.This paper summarizes the near-field theory of arrays and array signal processingmethods, as well as the theoretical model of the linear and semi-circular array under near-fieldconditions by near-field sound propagation characteristics. A near-field focusing results oflinear array and semi-circular array is given by the derived model, which summed up that thesemi-circular array can overcome the azimuth ambiguity compared to the linear array.For the unsatisfactory resolution ratio and direction estimation shortcomings of theconventional focused beam algorithm, this paper focuses on the near-field high-resolutionalgorithm. Comparing the conventional algorithm, MVDR algorithm, MNM algorithm andthe MUSIC algorithm use characters of the signal subspace and noise subspace on targetdirection estimation, so they have better resolution, better positioning accuracy.The conventional focusing algorithm’s array gain and noise suppression effect is notideal, the fourth-order cumulant algorithm is used to solve this problem, the use of thistheory’s character in spatial spectrum estimation makes the effective aperture of the basearray to be expanded, and makes Gaussian noise to be suppressed in the base array receivedata.This article focused on the combination of high order cumulant and high-resolutiontechnology with the application to the near-field target position estimation. Comparing withsimple application of high-resolution algorithm, fourth-order cumulant based high-resolutionmethod’s performance has significantly improved, it is mainly due to the nature of the highorder cumulant with the effective suppression of Gaussian noise, as well as the arrayextension. This paper compared the difference of the fourth order cumulant of high-resolutionalgorithm applied to the linear array and semi-circular array, and summed up the advantagesand disadvantages of the semi-circular array. Finally, taking into account the practicalapplication, this paper gave the preliminary design though the software, and used MATLABand VC++mixed programming method to design the software.