Research On The Technology Of Secondary Wave Modulation In Parametric Array Of Transient Signals

Since the 1960 s,the parametric array technology caused extensive concern of academic circles,many workers on the in-depth study of science and technology.Because in the case of small array size,using parametric array technology to low frequency can be obtained without sidelobe narrow beam sound waves,and can obtain wide signal bandwidth,so the parametric array technology has been in the bottom strata profile analysis,in the field of ultrasonic imaging and acoustic measurements widely used.Parametric array of transient signals are used as the excitation signal amplitude modulation of sine carrier to produce the original wave of parametric array,make the original wave of different frequency components in nonlinear medium,form a transient signal parameters.Because the parametric array secondary wave signal with the original wave signal is not linear relationship between the secondary wave is formed in the process of the wave propagation in a medium,so by the known secondary wave signal with the original wave envelope function;The parametric array secondary wave inverse demodulation technology,has many problems.If you would have a parametric array technology development for underwater acoustic communication and active acoustic offset,etc,need to study the transient signal parametric array secondary wave inverse demodulation method.This paper studies the two kinds of parametric array secondary wave inverse demodulation method,direct amplitude modulation demodulation method and double integral square root against demodulation method;The double integral open square inverse demodulation method is the theory basis of Moffett parametric transient signal array theory.Papers on two parametric array secondary wave demodulation method for computer simulation research,obtained by the demodulation parametric array secondary waves several kinds of periodic signal,linear frequency modulation signal and SINC corresponding parametric array signal when the original wave signal.In the pool of parametric transient signal array secondary wave inverse demodulation related experiments.Quantitative comparison of variance on the preset second wave signal acquisition with the experiment of the difference of the secondary wave signal,the data processing results show that the experimental results and theoretical simulation results very well.To verify the correctness of the theory,prove that the proposed parametric transient signal array secondary wave demodulation method is feasible.