The Research On Detection And Measurement Technology Of Underwater Target Transient Radiated Noise

With the continuous development of underwater steady radiated noise measurement technology and vibration and noise reduction technology,the steady radiated noise of various underwater vehicles and underwater weapons has been significantly reduced.Therefore,various countries begin to focus their research direction on Underwater Transient radiated noise measurement technology.In this paper,the measurement index of transient signal is studied and analyzed.The detection and calculation methods of the initial and end time of transient signal and the energy of transient signal are mainly studied.In this paper,the radiated noise signals of air-input water and ship rudder are taken as the research objects.Firstly,the sources,generation process and causes of air-input water and ship rudder noise signals are studied,and the radiated noise models of air-input water and ship rudder are established.Secondly,because the acquisition of the start and end time of the transient signal needs to be calculated on the basis of the output of the detector,the performance of the short-time energy detector,the high-order statistical detector,the Power-Law detector and the CFAR Power-Law detector in detecting the start and end time of the transient signal is studied.The air input water signal and rudder steering signal model are detected separately.The results of three detection methods under different signal-to-noise ratios are compared.The effects of data length and overlap on the detection results are analyzed.The characteristics of signal processing are compared and the appropriate parameters are selected for detection.Then the paper focuses on the analysis of signal-to-noise ratio,energy,signal start and end time,effective time,maximum peak and average peak of transient signal.Based on the output of the detector,the threshold for calculating the start and end time of the signal is designed to provide guidance for the measurement of transient signals.In addition,according to the characteristics of transient signals,the weighted average intensity histogram estimation algorithm is improved to estimate the azimuth of transient signals.The signal is truncated by the start and end time of threshold calculation and the real start and end time of signal respectively,and then the azimuth estimation is carried out.Comparing the azimuth estimation results of the two methods.Finally,the reliability of the algorithm is further verified by processing the experimental data of the pond and Songhua Lake.