Research On Underwater Transient Signal Detection And Directional Technology

It is a prerequisite for the enemy to discover the target in the modern naval battle and to overcome the enemy's victory.It is also the key technology of the intelligentization of the underwater weapon in the national defense modernization.The study of transient signal detection and orientation technology for the small target water inflow has been paid much attention by the world's major ocean powers.The main contents of this paper are as follows: This paper expatiates on the generation mechanism of transient input signal and its mathematical modeling and analysis.This paper introduces the application of time-frequency analysis method such as short-time Fourier transform,Vickers-Wiener transform and wavelet transform in transient signal processing,and analyzes its advantages and disadvantages.The theory of Hilbert-Huang transform is introduced,and its definition of instantaneous frequency,intrinsic modal function and empirical mode decomposition(EMD)are introduced.The completeness and the orthogonality of the EMD are discussed,that is,the modal aliasing phenomenon exists.The empirical mode decomposition theory is introduced,which effectively overcomes the phenomenon of mode mixing.The effect and performance of each compared before and after decomposition.The short-time energy detection,short-time correlation detection and Power-Law detection theory are analyzed,and the simulation signal is simulated and analyzed.Collecting transient signal experimental data in the pool,in order to study the problem of transient signal detection under weak target,the noise is added to the transient signal.The signal was analyzed by EMD decomposition and CEEMD decomposition and reconstruction.The effect and performance of each compared before and after decomposition.The principle of beamforming of 5-element array signal is introduced,and the principle of beamforming is used to study the transient signal.This paper introduces the application of single vector hydrophone in signal direction finding,and introduces the principle of azimuth method and average azimuth method.The azimuth determination of the acquired transient signal is carried out using the histogram azimuth determination.