【作者】 宋春艳；

【导师】 张兴周；

【作者基本信息】 哈尔滨工程大学 ， 通信与信息系统， 2005， 硕士

【摘要】 混沌是非线性动力学系统所特有的一种运动形式,是确定性的、类似随机的过程。混沌信号具有遍历性、非周期、连续宽带频谱、似噪声的特性。随着混沌同步的方法不断涌现,混沌系统同步及其在保密通信中的应用问题引起了人们的广泛关注,从实际应用出发,如何找出同步技术的最佳方案,越来越成为当今的研究热点和难点问题。 本文在深入分析了多种混沌同步方案的基础上,从三个方面研究了提高混沌同步通信系统保密性的方法:选用更为复杂的超混沌系统作为调制模块中的混沌源;采用更为复杂的信息信号调制方式;改变信号的传输方式。在研究的过程中,将理论分析、计算机仿真、数值计算有机的结合起来,为混沌或超混沌同步在保密通信中的应用提供了理论基础和实验依据。 提出了一种新的基于主动一被动同步的混沌保密通信方案。通过和原来的方案对比分析,发现新的方案不但加密变量的获取过程较为简单,互相关特性好,且同步时间特性、信号恢复精度均优越于变参数混沌同步保密通信方案。系统对参数的敏感性高,满足保密通信的技术要求。 根据外部混沌信号驱动混沌同步原理,采用离散的R(?)ssler混沌系统的变量,驱动两个参数相同的Lorenz系统同步。指出在一定条件下,间歇驱动混沌同步方案的同步效果和驱动强度系数、采样周期有关。在保密通信中,应用间歇驱动混沌同步方案,信号恢复的效果好,而且系统具有一定的鲁棒性,信息信号能很好的淹没在混沌变量中,系统的密钥多。 在对超混沌系统的研究中,分别讨论了非时滞超混沌系统同步保密通信和时滞超混沌系统同步保密通信。指出时滞超混沌系统相对于非时滞超混沌系统具有不可取代的优越性。在保密通信中,超混沌系统具有更高的安全性,仍是今后一段时间的研究热点。更多还原

【Abstract】 Chaos is a special moving form of nonlinear dynamics system, and it is definite and random like process. Chaotic signal has the properties of ergodicity, nonperiodicity, continuous broadband power spectra, and noise like etc. Along with the appearance of chaotic synchronization methods, chaotic system synchronization and its application in secure communication have aroused the attention of people. How to find the best scheme of synchronization is becoming today’s hotspot and difficulty of research more and more.On the basis of analyzing many kinds of chaotic synchronization methods, three methods of improving the security of chaotic synchronized communication system is studied: choose more complex hyperchaotic system as the chaos generator of modulation; adopt more complex modulating method of information signal; change the transmission method of signal. Theory analysis, computer simulation and numerical computation are combined together and it provides theory and experiment foundations.A new chaotic secure communication scheme based on active-passive synchronization is propoed. By contrast analysis with the original scheme, find that not only the complexity of system is reduced, but also the capability is enhanced. At the same time, it does not destroy the correlation. The experimental results show that the proposed method can recover signals well. The new scheme meets the command of secure communication.According to the principle of synchronization driven by chaotic signal outside, adopt discrete varialbles of Rossler chaotic system to drive two Lorenz systems with equal parameters to achive synchronization. Point out that under some condition, the synchronous effect of the chaotic synchronization scheme driven by intermittent signal has relation with the coefficient of driven intension andsampled period. We applied the chaotic synchronization driven by discrete chaotic signal to secure communication, the system possesses robustness, the information signal can be hiden in chaotic variables, and its keys are resourceful.In the study of hyperchaotic system, the secure communications of hyperchaotic system synchronization without time-delay and with time-delay are discussed. Point out that hyperchaotic system with time-delay has much superiority than that without time-delay. In secure communication, hyperchaotic system is of high security, and it will still be hotpoint in the later time.更多还原