Research And Implementation Of Underwater Acoustic Spread Spectrum Communication Technology Based On Array Reception

No matter what kind of communication mode,the propagation characteristics of the underwater acoustic channel have a great influence on the effectiveness and reliability of underwater acoustic communication systems.The influence of multipath interference and Doppler is often a concern in the past,but the direction of arrival(DOA)of the underwater acoustic signal is also a kind of channel information.For a single receiving sensor,the multipath interference will seriously affect the communication quality.For array receiving,the DOA can be used for beamforming to suppress the multipath interference and improve the signal-tonoise ratio,to improve the communication performance.However,the underwater channel has a serious multi-path,the channel structure changes at any time when the relative motion of transmitting and receiving occurs,and the working signal-to-noise ratio of the spread spectrum signal is low,leading to the failure of some high-resolution array signal processing algorithms.The above series of problems have a serious impact on the practical application of array signal processing algorithms in underwater acoustic spread spectrum communication.Therefore,this paper will carry out research on underwater acoustic spread spectrum communication algorithm and array signal processing algorithm for the realization of underwater acoustic spread spectrum communication system based on array reception.Firstly,this paper studies the water acoustic spread spectrum communication with single transmission and single reception,introduces the basic principle of spread spectrum communication,focuses on analyzing the influence of the Doppler effect on spread spectrum signal,and introduces two methods of time-frequency two-dimensional search and copydependent Doppler estimation.Then,the influence of the carrier phase on communication performance and its solution are introduced.Finally,the underwater acoustic spread spectrum algorithm is verified by experiments.The array processing algorithms of underwater acoustic spread spectrum signals are divided into two categories: DOA estimation and broadband beamforming.In this paper,the multiple signal classification(MUSIC)algorithm based on m sequence and space-time cluster DOA estimation algorithm suitable for spread spectrum signal are proposed,and their performance is compared with conventional waveform formation and incoherent signal subspace methods.Aiming at the problem of spread spectrum signal beamforming,the phase shift,delay and sum,frequency domain,and the minimum variance distortionless response(MVDR)beamforming algorithms are introduced,trying to select the appropriate beamforming algorithms in different application backgrounds.Then,the array signal processing algorithm is introduced into the underwater acoustic spread spectrum communication.Considering the space-time cluster characteristics of the underwater acoustic signal,the beam diversity receiving algorithm is analyzed and studied.Through simulation and multiple field experiments,it is proved that beam diversity receiving can make full use of array gain and path gain and effectively improve communication performance.Finally,the array receiver-based underwater acoustic spread spectrum communication system is implemented and tested.In practice,it is verified that the performance of spread spectrum communication is improved after using an array receiver.The main purpose of this paper is to provide a reliable algorithm for the application of array signal processing in underwater acoustic spread spectrum communication,to improve the performance of underwater acoustic spread spectrum communication.