The Correlation And Time-frequency Analysis Of The Line Spectrum Component Detection For Acoustic Fuze

With the rapid development of signal detection and processing theories and considering the use of it in the acoustic fuse technology in the last decade, in this thesis the line-spectrum detection of ship-radiated noise is studied. We apply some modern signal processing and traditional signal processing methods to underwater signal detection and processing, the main research works and progress are as follows:1. Firstly, the traditional autocorrelation method is studied in the detection of weak sinusoidal signals. A new method is proposed that can be used in detecting weak signal. Because of the sinusoidal signal has a particular autocorrelation trait, it is possible to detect the weak sinusoidal signal in powerful noise by multi-layer autocorrelation. At the same time, the line-spectrum detection based on symmetrical correlation function is also studied. The results show that the method is better and more effective than conventional correlation method when it is used to suppress random noise and detect line-spectrum. On the other hand, the theory of polarity correlation is also studied. Through theory analysis and simulation, it is proved that this method can greatly reduce calculation cost.2. Secondly, based on modern spectral analysis the method of Levinson is studied and introduced to cross-correlation. The algorithm of cross-correlation can efficiently overcome the shortcomings of low resolution and high variance which are existing in both classical FFT and cross-periodogram methods. The feature of underwater moving-target can be extracted by the united spectrum estimation based on the traditional and modern spectrum estimation. The results show that this method is well-rounded and simple and detect the character of target timely,3. Because of the limitation Fourier transform on processing signals, which are carried out in time domain or frequency domain only, time-frequency analysis methods are raised. In this thesis, the short time Fourier transform, Winger-Ville distribution, Winger-Hough transform (WHT)are described in details. By comparing the performances, the advantages and disadvantages of these three methods are pointed out. The method of the short time Fourier transform can detect the line-spectrum of ship-radiated noise well with the reasonable window. The application of Winger-Hough transform in detection of underwater transient signals was demonstrated. It could be found out that the output...