The Broadband Signal Of Underwater Target Echo Simulation In Time And Frequency Analysis

Submarine is the most dangerous covert operations platform.For submarine detection and recognition has been the surface ships,especially the main task of the anti-submarine type formation escort ships.Underwater target strength and continuous decrease of radiated noise at the same time,makes the sonar detection target ability also decreases,therefore,for the realization of the efficiency of the sonar systems,it is necessary to work for new system to carry out the exploration work.It is in this background,the underwater target echo characteristics has been attached great importance to,especially in underwater target low frequency acoustic scattering characteristics research,better development for the application of acoustic technology is an important basic research.This paper first introduces the characteristics of the broadband signals needed for detecting target,and according to the analysis of ambiguity function of several common active sonar signal in frequency,range,noise resistance,resistance to reverberation aspects of advantages and disadvantages,as the study of active sonar target echo of emission right waveforms.Second,according to the acoustics theory foundation,the strict solution of acoustic scattering theory and approximation theory,establish a rigid ball,cylindrical geometry model of simple shape objects such as rigidity,the acoustic characteristics of target strength and sound field sound pressure calculation,the selection of typical target echo window model as the carrier of target echo.Based on point model of target echo simulation,and by changing the target shape,active sonar waveform or irradiation direction and other factors,to study the effect on the echo signal.Then,according to the target echo simulation based on the point model,we simulate target echo.And we research the influence of the targets geometry such as cylinder,round shell and underwater scale goals and active sonar waveform such as CW,LFM signals.By changing the detection target geometry,active sonar waveform or irradiation direction and other factors,to study the effect on the echo signal.The last of the broadband signal processing method,instant frequency analysis some generalization and summary are made,mainly using the short-time Fourier transform and wigner distribution of target echo signal two methods of time-frequency analysis,finally summarizes factors affecting the target echo characteristics.