The Reconsitution Science Of Ship Radiated Noise Character

The ship-radiated noise is one of the most important physical fields in underwater countermeasures, and widely used in mine and MCM equipment. In order to countermeasure the acoustic mine with increasing target recognition capability, the most effective method is to simulate underwater radiated noise of protected ships and make enemy mine difficult to distinguish whether true or false.Distinguishing the ship type and speed is mainly based on the acoustic spectral characteristic, and reflecting the dynamic process of ship passing the measuring point from far to near is based on the acoustic through characteristic. Based on underwater radiated noise of protected ships, the spectral characteristic and through characteristic are reconstructed and the problem of what and how to simulate is solved in the dissertation.The acoustic spectral characteristic reconstruction and control algorithm is primarily studied in the dissertation. The ship-radiated noise sources and basic characteristics are briefly introduced, and the information process of spectral characteristic reconstruction is analyzed in detail, and the necessity of real-time spectrum analysis and control is proved by using the loop time. By comparing four kinds of classical power-spectrum estimation algorithm, Welch periodogram power-spectrum estimation is selected.The spectral characteristic reconstruction and control algorithm is proposed, and an improved method of phase modulation is proposed. Through the simulation, the results show that the method has high spectral-line qualified rate and good smoothness, which effectively solves the problem of how to add phase from power-spectrum into complex-Fourier-spectrum.The effects of the spectral-line number, the control step and the average frame number on controlling spectrum smoothness are analyzed by simulation. The results show that more spectral-line numbers, smaller control steps and more average frame numbers lead to better spectrum smoothness.The solutions to the problems in the frequency control system, such as how to overcome the effect of the non linearity of control targets, how to obtain the transfer function of cascading devices and how to generate control spectrum through measurement spectrum, are proposed. On the basis of the information process of spectral characteristic reconstruction and the spectral characteristic reconstruction and control algorithm, the construction scheme of the spectrum control system is proposed.