Research On Covert Underwater Acoustic Communication

With the expanding field of application of Underwater Acoustic communication,Underwater Acoustic communication technology has become the hotspot of research on Underwater Acoustic Technology. As Communication technology has been known as the lifeline of the world economy and military, covert communication is the tactical advantages of military application. The main obstacle in the field of underwater acoustic communication is the complex propagation paths and the Doppler Effect that cause signal fading and signal distortion respectively. The research on covert underwater acoustic communications technology in such a complex environment will undoubtedly become a research hotspot in the future.Covert communication techniques are divided into active covert communication and passive covert communication. This thesis has a research on chaos spread spectrum communication, chaotic pulse-width-position modulation (CPWPM) communications and whale sounds cover chaotic spread spectrum communication which belong to random coding, random burst and bionic camouflage covert mechanism respectively in the field of passive covert communications. The main work is as follows:1. Summarizes the channel characteristics and its impact on the water underwater acoustic communication. Introduces several effective methods of channel statistics character analysis. Focuses on the more popular channel modeling with the statistical characteristics,and compare the modeling results with the real channel to verify the validity and accuracy of the channel modeling with statistical properties.2 . Introduces Logistic, Tent and Chebyshev three kinds of one-dimensional discrete-time chaotic mapping principle, and describes the analytical methods of chaotic characteristic. A study on the generation method of chaotic spreading code and Chaos Spread Spectrum Communications, and analyzed the chaotic spread spectrum communication system characteristics by MATLAB simulation and analysis of field experiments.3. Introduces the modulation and demodulation method of CPWPM system. Describe the analysis methods of the CPWPM technology, and analyzed the CPWPM system characteristics by MATLAB simulation and analysis of field experiments.4. Studied on whale sounds cover chaotic spread spectrum communication, and analyzed the bionic camouflage covert mechanism system characteristics by MATLAB simulation and analysis of field experiments.