【作者】 李春福；

【导师】 虞厥邦；

【作者基本信息】 电子科技大学 ， 电路与系统， 2001， 博士

【摘要】 本文主要内容涉及基础研究和应用研究，其中包括：1）进行了关于混沌信号发生器的若干研究；2）进行了关于混沌信号处理的若干研究；3）进行了关于混沌信号在保密通信和跳频扩频通信中的应用的若干研究。 本文的主要创新之处可概述如下： 1.关于混沌信号发生器的若干研究。 （1）提出了一族新的基于平方非线性函数的混沌模型，计算了它们的李雅普诺夫指数。此平方混沌族中的三类模型都表现出了倍周期分岔到混沌的过程，而在第Ⅲ类结构中可以观察到环面破裂和倍周期分岔两种不同的通向混沌的途径，在同一个系统中可以观察到环面破裂和倍周期分岔两种不同的通向混沌的途径，相信是混沌生成研究方面的首次报道；在三阶自治系统中可以观察到环面破裂，这也是一个很少见的现象。 （2）对本文所提出的第Ⅲ-a种新的单涡旋混沌模型进行了分段线性电路实验研究，其分段线性电路实现只需一个非线性器件，即一个三段线性电压控制电压源或两段线性电压控制电压源，从整体电路结构来看，它比蔡氏电路要复杂，然而它可以采用两段线性电压控制电压源来实现，因而就非线性器件的复杂程度而言，它是最简单的混沌发生器。 （3）提出了一种新的变型蔡氏电路，给出了此变型蔡氏电路的一种具体电路实现方法；对此变型蔡氏电路的动力学行为进行了仿真研究，且计算出了此变型蔡氏电路的李雅普诺夫指数。 （4）提出了一种构造新的混沌或者超混沌模型的电阻性混沌模型耦合方法，并且给出了用此方法构造的几种新的混沌吸引子，对所构造的新的混沌 os吸5吁进行了数值研究，赠了其李雅普诺夫指数，将耦合形成的新的混饨吸引子与耦合之前的混饨吸引子进行了对比颁。 2．关于混淹怕号处理的苦于研究 ＊）提出了基于Volterm级数模型。TLS准则和迭代h3算法的Voterm－TLS方法，实验证明，当用于混饨时间序列预测时，Wlterra．xtal方法的预测精度不低于Vb：lterrsiNlma s方法的娜精度，并且Vbllerrsiis3方法具有更快的训练学习速度和更强的抗噪声干扰能力。 p）提出了一种混饨信号降噪的微扰方法，其基本思想是通过在观测轨道YN＝blot，…砌上施加一系列适当的微扰来逐步得到真实轨道 XN ＝＝（x—，…砌的估计值及。＝＝（Z，又，…，、几实验表明，梯度微扰法在低信噪比时仍然能够得到很好的降噪效果。 3．羌于沼浊仙号在回们系统中应用的奢干研究 ＊）提出一种新的模拟混饨加密摊，并进行了呛晌真和硬件电路实验研究，实验证明这种新的模拟混饨加密方法是可行的。 （2提出一种新的基于密码准混饨序列的密码与跳频技术相结合的跳频通信系统，并且进行了协议部分、拂信号处聊分、射频调制／解调算法部分的仿真研究和系统的硬件实验研究；研究了利用混饨信号产生伪随机序列的有限精度实现问题，利用本文提出的M业肚m－113方法对密码准混饨序列产生的跳频码的抗鹏干扰能力进行了仿真实验研究。更多还原

【Abstract】 In this dissertation, researches on chaotic signal generating, processing and application in communication systems are carried outHie main originality in this paper can be summarized as below: 1. Studies on chaos generation.(1) A new chaos family based on quadratic function is promoted, their Lyapunov exponents are calculated. In the proposed three types of chaos generator belonging to this chaos family, the period-doubling-bifurcation route to chaos is observed, and in the type-in chaos generator, the torus-breakdown route to chaos is also observed. It would be a firstly observed phenomenon that the period-doubling-bifurcation route to chaos and the torus-breakdown route to chaos coexist in a same system, and it is a rarely observed phenomenon that the route of torus-breakdown to chaos can be observed in a third-order ordinary differential system.(2) Piece-wise linear (PWL) circuit realizations of the class-DI-a chaos generator are suggested. In the circuit realizations, only one nonlinear element is needed, that is, only a three-segment PWL voltage-controlled vokage source or a two-segment PWL voltage-controlled voltage source is needed. In the context of the whole circuit structure, this circuit realization is more complex than that of Chua’s circuit, but in the context of the complexity of the nonlinear element employed, it is the most simple chaos circuit while realized by a two-segment PWL element.(3) A modified Chua’s circuit is proposed and a circuit implementation is also designed. Dynamics of this modified Chua’s circuit are numerically studied and its Lyapunov exponents are also calculated.(4) A resistance-coupling method for designing new chaos generators by taking use of existing chaos generators is suggested, several new chaos generators realized by this way are studied and their dynamic are compared to those of original chaos generators, their Lyapunov exponents are also calculated.2. Studies on the processing of chaotic signal(1) A novel Volterra-TLS method based on Volterra series model, TLS criterion and iterative TLS algorithm is proposed. It is proved by numerically simulation that, when used for predicting the chaotic time series, the predicting precision of Volterra-TLS method is not inferior to the predicting precision of Volterra-NLMS method while its training and learning speed is faster and it is more ro^w; against noise interference.(2) A new perturbation method for noise reduction of chaotic signal is promoted, the approach consists of deploying a series of proper disturbance to the observing orbit YN = (yi,y2,.-.j//)?so as to gradually acquire the estimation XN - (Jc,,5c2,...,jcw) of the real orbit XN = (*i,X2,...,XAr). It is proved by numerically simulation that the disturbing method can still obtain fairly good noise reduction results even if the signal-to-noise ratio of input signals is low. 3. Studies on the application of chaotic signal in communication.(1) A new approach for chaotic secure analog communication is promoted, it is proved by both the computer simulation and hardware experiment that this new chaotic encryption method for analog secure communication is feasible.(2) A new digital frequency-hopping communication system based on cipher-quasi-chaotic sequence is proposed, which combines the cryptography and frequency-hopping technology. The system’s protocol, base-band signal processing and modulation/demodulation algorithms of the radio-frequency part are designed, and the hardware experiment conducted on a prototype of the system show that the system functions well. The finite precision problem arising while taking use of chaotic signal to generate pseudo-random sequence is studied and the anti-tracking capability of the cipher-quasi-chaotic sequence is studied with the Volterra-TLS method proposed in this dissertation.更多还原