| In recent years,the scale and speed of marine development have been accelerating,and the investment in national defense construction in the field of hydroacoustics has also increased,and the development of underwater acoustic communication technology has developed rapidly.At present,most researches in the field of underwater acoustic communication are still only focused on improving communication speed,range and communication quality.The research on underwater acoustic communication technology in which the transmission power is constrained,that is,the signal-to-noise ratio needs to be at a very low level,is not deep enough.However,we usually need to limit the size of the signal transmission power and the distribution of the spectrum to a certain extent.For example,in the civil field,if there is a node with too high transmission power in the underwater acoustic communication network,other nodes will be interfered with and even af-fect normal communication;in the military field,if the power during signal transmission is too high,it will result in The signal is easily intercepted and our target is exposed.In order to realize reliable underwater acoustic communication technology under low power,the design of the signal waveform at the transmitting end is particularly important.Chaotic sequences are a series of information sequences that have emerged in recent years and are difficult to be captured and tracked.In recent years,they have been widely used in systems such as optical communication,underwater acoustic communication,and low intercept probability communication.Spread spectrum communication technology is a mature technology in the field of underwater acoustic communication.It has good anti-interference ability and confidentiality.The combination of chaotic technology and spread spectrum technology has brought a lot of room for development of underwater acoustic communication technology.Focusing on chaotic spread spectrum technology,the main work of this paper is as follows:A new chaotic sequence for chaotic communication systems is proposed.Based on the diversity,good autocorrelation and cross-correlation properties of chaotic sequences,some improvements are made to the existing chaotic sequences,and the I transmission waveforms of chaotic spread spectrum communication are designed.An algorithm for chaotic spreading using real-valued continuous chaotic sequences is proposed.The short period problem caused by quantization of digital chaotic sequences and the problem of large amount of information loss are avoided,which not only retains the characteristics of high concealment and low bit error rate of spread spectrum communication,but also preserves sufficient diversity of chaotic sequences.3.Combine chaotic spread spectrum communication with transform domain communication,analyze the ambient noise and interference using the transform domain spectrum,reconstruct the"clean"transform domain spectrum of the signal,and get a new basis function to send out,correspondingly through the receiving end.The module achieves the separation of interference and signal.The simulation and sea trial results show that the proposed scheme can achieve reliable communication under a low signal-to-noise ratio,and can inhibit the adverse effects of underwater acoustic environment on communication to a certain extent,thus enhancing the chaotic underwater acoustic communication system.The purpose of concealment and anti-interference.The scheme can be used in the fields of secure communication,covert communication and anti-interception communication in underwater acoustic communication. |
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