Study On Chaotic Sequence Spread Spectrum Underwater Acoustic Communication Technology

Underwater acoustic channel environment is very complex which shows up the performances of the quick change of the time and the frequency domain,the severe limitation of the available frequency band and the very highness of the environment noise.These characteristics hindered the development of high quality underwater acoustic communication.The performance of spread spectrum communication technology is outstanding including the anti-interference,anti-multipath,and transmitting information accurately in the low SNR.Research has shown that the methods of generating chaotic sequences is simple,chaotic sequence has large quantity and good disguise.It can achieve highly efficient communication if combined with the spread spectrum technology.Time reversal mirror technology is applied to the chaotic spread spectrum communication,it can overcome the bad condition of underwater channel communication,and achieve high efficiency and reliable decoding.This paper conducts in-depth research into the chaotic sequences spread-spectrum underwater acoustic communication system.Firstly,the research on the types of chaotic sequences is introduced,summarizes the advantages of chaotic sequences as spreading codes,presents a simulation of the real value sequence and binary sequence generation method.On this basis,the pseudo random property of the chaotic sequence is discussed.Secondly,the paper describes the combination of the chaotic spread spectrum sequences and underwater acoustic spread spectrum communication system,the completion of the scheme design of differential chaotic direct sequence spread spectrum underwater acoustic communication and the discussion of comparative analysis of the first differential coding and first spread spectrum encoding.Next,the cyclic shift chaotic spread-spectrum communication is discussed,based on that,M-ary chaotic spread-spectrum is mainly studied,then combining the cyclic shift keying spread spectrum and M-ary chaotic spread spectrum with TRM.Lastly,the algorithm was carried on computer simulation experiment and lake test validation which both showed the results that: chaotic sequence is a good spread spectrum sequence,it can realize the reliable decoding in underwater acoustic communication,the combination of TRM technology and chaotic sequence spread spectrum underwater acoustic spread spectrum communication can further improve the system robustness.