Research On The Scale Estimates Algorithm Of The Ship Target Characteristic

An important technical index for modern intelligent mine is that, whether or not, it can accurately recognize the attacking targets and successfully conflict the anti-mine weapon. The performance of a modern mine on this technical index depends on the fuze system of mine, which is responsible for detecting, recognizing, and analyzing the attacking ship objective. There are many physical fields can be used to design the fuze system of mine, of which the most important one is the ship-radiated noise. Based on the mine fuze passive receiving system, we are trying to change the conventional object identification as a point target into object identification as a volume target in this paper. The corresponding periodic results have been achieved. Specifically, to obtain the attacking ship object passive scale estimation algorithm, we did the following work:1. The property of the ship-radiated noise is analyzed concisely. The simplified ship three-speck model is the basis of the scale estimation algorithm. For further passive scale estimation, a simplified physical model is established; where the ship is simplified as a region with three lighten areas or three specks according to the difference in frequency and energy between the main parts in a ship such as the auxiliary machine, the main engine, and the propeller.2. The empirical mode decomposition is applied for the ship-radiated noise. Using this method, the ship-radiated noise is adaptively decomposed into several intrinsic mode functions. Then the refinement spectral algorithm is constructed based on the Fourier transform, with which the useful information of the ship-radiated noise is sifted.3. According to the Hilbert transform and the corresponding analytic signal theory, the instantaneous phase and instantaneous amplitude algorithm, the instantaneous amplitude and the instantaneous phase function of the ship-radiated noise are achieved. Thus, the rearranged energy of the ship-radiated noise in time domain is displayed, from which the scale information of the attacking ship is obtained.4. The mathematical model of the single speck without object scale information is established, and the corresponding numerical results are obtained, from which the applicability and the effectiveness of the empirical mode decomposition algorithm are illustrated.By applying the proposed algorithm to the numerical simulation noise and the real ship noise and comparing the computed results with the real ship scale information, it is clear that the proposed algorithm works well. On one hand, the proposed scale estimation algorithm works well for the high signal-noise-ratio real ship data; on the other hand, it recognizes the single speck simulation signal without scale information. Therefore, the desired goal of this thesis is implemented. The proposed algorithm based on the empirical mode decomposition has the following advantages: it can be easily implemented, the computational speed is fast, and it can be clearly understood. It is supposed to be applied into practical engineering after the improvement in the aspect of engineering stability.