Research Of The Acoustic Communication System Based On The Weak Signal Detection By Chaos

With the continuous progress of science and technology in the world,the development of acoustic communication is rapid and its application area is expanding.Acoustic communication was first used in military field,and it is mainly used in underwater acoustic communication.Because of the severe attenuation of electromagnetic wave and light wave in water,acoustic wave is the best method for the long distance communication under the water.With the popularity of mobile intelligent terminals,they communicate with sound waves in short distance.The technology of acoustic communication between mobile intelligent terminals is a developing trend in the future and has broad prospects.Weak signal detection in the strong noise background is a vital technology in acoustic communication system.Compared with filtering and suppressing the noise to extract the effective signal,chaos has more potential in the weak signal detection field because of its sensitivity to the periodic signal with specific frequency and strong immunity to the noise.First of all,the paper takes the Duffing system as the research object,and analyzes its chaotic characteristics and dynamic characteristics.Study the weak signal detection ability,anti-jamming ability and detection sensitivity of the duffing system by Matlab simulation.Multisim circuit simulation has been done and Duffing chaotic circuit board has been designed and made to confirm the ability of weak signal detection in Duffing system.At last,some problems of Duffing system in weak signal detection such as the the narrow detection and difficulty of distinguishing chaotic states and periodic state are raised up.These problems limit the application of the Duffing system in practical engineering.To solve the problems of Duffing system,improve the model of Liu system and get the similar Liu system.Analyze the chaotic characteristics and the dynamic characteristics of the similar Liu system.Study the weak signal detection ability,anti-jamming ability and detection sensitivity of the similar Liu system by Matlab simulation.Multisim circuit simulation has been done and similar Liu chaotic circuit board has been designed and made to confirm the ability of weak signal detection in similar Liu system.The experimental results show that the similar Liu system can solve the problems of the Duffing system.By comparing the weak signal detection performance of Duffing chaotic circuit board and similar Liu chaotic circuit board,including time domain signal detection performance,wide area detection performance,detection of frequency accuracy,anti noise ability and system stability,come to the conclusion that the similar Liu system has the advantages of periodic convergence and wide area detection,while the Duffing system has stronger anti noise ability and higher stability.Finally,the Duffing-filter system and Duffing-similar Liu combined chaotic system are proposed to solve the problem of duffing system that the chaotic state and periodic state is difficult to distinguish.Finally,establish the air acoustic communication system and underwater acoustic communication system.The air acoustic communication system mainly does research on the performance of the chaotic system to detect the low frequency acoustic signal and the underwater acoustic communication system is used to study the performance of the chaotic system to detect the higher frequency acoustic signal.Through the experiment of acoustic communication,the paper makes an attempt to apply the chaotic circuit board to the actual signal detection and it is proved that the chaotic system is feasible to detect the real signal.