Measurement And Analysis Technology For Wideband Radiated Noise Of Underwater Moving Target

As the vibration and noise reduction technology improved, then the methods of radiated noise measurements faces new technology challenges, therefore, it's very important to improve the technology of radiated noise measurement and analysis using vertical array with constant beamwidth beam-forming.Two techniques of constant beamwidth beam-forming are researched; the first one is nested array constant beamwidth beam-forming. According to the shallow sea situation of radiated noise measurements, the vertical nested array radiated noise measuring system is designed, and discussed the influence on the result of radiated noise measurement when there are some errors. When the low frequency signal should be dealing with, the nested array aperture size will be very large; the large aperture size array is not suitable for processing low frequency signals in shallow sea.Aiming at low frequency of radiated noise, the linear array constant beamwidth method based on notch filter is presented. This method change the low-frequency signals into high-frequency signal by using the signal parameter estimation theory based on notch filter and the off-line reconstitution theory, then, process the high-frequency signals using the method of traditional beam-forming to get the constant beam width.At last, based on the two methods in this paper, the experimental data is processed. The results illustrate the two techniques of constant beamwidth beam-forming efficient. The nested array constant beamwidth beam-forming technique and the linear array constant beamwidth method based on notch filter can be used to measurement radiated noise.