Research On Signal Waveform Recovery Using Multi-nodes

The acoustic signal emitted by the sound source is transmitted to the receivers via a shallow sea channel.Due to the influence of environment noise and multi-path effects,signal waveform received by hydrophone is distorted severely.Based on spatial filtering and deconvolution,this thesis studies the waveform recovery of the pulse signal of the sound source.Firstly,the source of waveform distortion in shallow channel is analyzed and a waveform recovery scheme is designed.The main causes of signal waveform distortion are noise,interference and channel multipath.This paper proposes two ways to recover the signal waveform.One is using beam former with spatial filtering characteristics to remove the noise interference effect which is different from the source direction,realize the sound signal waveform recovery.The other one is using deconvolution method to remove the influence of multipath,realize waveform recovery.Besides,the correlation coefficient is used to evaluate the result of waveform recovery.Then,the research focuses on the method and its performance of interference suppression waveform recovery based on uniform circular array.The wave direction of the target signal is obtained by deconvolution beamforming based on Lucy-Richardson iterative formula.According to the wave direction of the target signal,time delay compensation is performed on the received data to suppress the interference signal different from the incoming wave direction of the target,thus the waveform recovery of the sound source emission signal is realized.The waveform recovery performance of this method is affected by the direction of arrival which comes from the interference and the target.When the interference incoming wave direction is located at the zero point of the beam pattern,the waveform estimation performance is optimal.Finally,the waveform recovery method under multi-path condition based on multi-nodes is given.By performing deconvolution processing on the received signal and the channel impulse response function,the influence of the multi-path effect on the received signal is removed,and the waveform recovery of the sound source transmitted signal is realized.The multi-nodes system is used to locate the sound source,and the multi-channel is solved basedon the geometric position relationship between the target and the receiving nodes.The performance of the waveform recovery method based on deconvolution is analyzed.The results show the method has better waveform recovery performance at high signal-to-noise ratios,the delay difference between multiple arrivals and the amplitude difference are large.The validity of the algorithm is verified by processing actual experimental data.