Bounded Sediment Acoustic Parameters Measurement Method Research In The Space

With the deepening of marine environmental research and application,the acquisition of acoustic parameters of seabed sediments has become increasingly important in acoustic propagation modeling research.At present,the main acquisition methods are point-in-place measurement and inversion.For the measurement of the sound velocity of seabed sediments,the key is the propagation time extraction.Therefore,this paper mainly studies the time delay estimation algorithm under different signals,simulates it,and validates it with experimental data.The paper first introduces the problems in the sound velocity measurement of sediments on the seabed,analyzes the development history and research status of time delay estimation,and summarizes the difficulties encountered in the current time delay estimation,mainly due to the presence of noise,multi-path interference,and signals.The time-varying and wide-band signals.Then,the measurement method of sound velocity dispersion and narrowband in sandy sediments is introduced.In the bounded space,the speed of sound is calculated according to the time delay estimation.For the existing problems,four algorithms are studied:cross-correlation method,higher-order spectrum method,subspace Decomposition method and subspace fitting method.The four algorithms are compared and analyzed to analyze the effects of noise size,pulse width,and windowing on the performance of the algorithm.The application of various algorithms in different environments is analyzed.Finally,the experimental data is processed to analyze the existence of the main experimental results.Error,design improvement algorithm.The broadband measurement method of sound velocity dispersion in sandy sediments is introduced.The necessity analysis of wideband sound velocity measurement is given.A broadband measurement algorithm based on pulse compression technique is proposed and simulated.The design laboratory's wide-band measurement of sound velocity dispersion in sandy sediments was conducted,and the experimental data was finally processed.In order to avoid multi-path interference,the signal pulse width used in the pool experiment is narrow.Due to the high frequency of the signal,the bandwidth of the transmitted signal is large.In order to make the spectrum of the transmitted acoustic signal as close as possible to the spectrum of the desired signal,the paper applies the measured transducer's transmit voltage response to compensate the drive signal to reduce the distortion of the acoustic signal waveform caused by insufficient bandwidth of the transducer.Firstly,the numerical simulation of this method was carried out,and the validity of the method was initially verified.On this basis,the experiment of the laboratory pool was carried out.The experimental results show that after the driving signal is compensated,the frequency peak offset of the narrowband acoustic signal is significantly reduced,and the bandwidth of the broadband acoustic signal is closer to the bandwidth of the driving signal.The transducer drive signal compensation method broadens the working bandwidth of the transducer,reduces the fluctuation of the broadband measurement data,and improves the matching with the narrowband data.