Study On Chaotic Sequences Properties And Synchronization Technology

Chaos is a convinced and similar random process that appears in the nonlinear system. It is also a non-periodic and irregular process. It is not convergent but has a bound, also it is sensitive to its initial values. For all these specical properties, chaos has good application prospect in the field of secure communication and spread spectrum communication. With the deepening studying to the chaos phenomenon, chaotic synchronization has become the improtant subject in this filed.This paper introduces the basic theories of chaos including the definition of chaos, the development of chaos technology, chaotic sequences map and their typical applications. Then the statistical properties of the four kinds chaotic sequences are analyzed, including attractor, Lyapunov exponents, bifurcation diagrams, fractal and dimension, phase characteristics, power spectrum characteristics, balance, run-length features, correlation, and the simulation results are given.The definition of linear complexity is introduced. The Massey algorithm, classical K-S entropy algorithm, approximate entropy (ApEn) algorithm, permutation entropy(PE) algorithm, index in primitive production process (IPP) algorithm and Lempel-Ziv complexity algorithm are studied. The complexities of the four kinds chaotic map are compared and analyzed. The values of various complexity algorithms analysis are given.The basic principles of chaotic spread spectrum communication are introduced. A new optimized selection algorithm of chaotic spread-spectrum sequence is proposed, and the optimal improved chaotic sequences are applied to DS/CDMA system in the presence of AWGN and different kinds of jamming. The results show that the chaotic spread-spectrum sequences generated by the proposed method have better correlation performance, larger capacity and excellent anti-jamming ability.Several chaotic synchronization technologies are studied, including PC synchronization, coupled synchronization, associated synchronization and active-passive synchronization.Their basic principles and the example simulation are given. For the specific applications of chaotic ranging system, based on digital matched filter to achieve chaotic acquisition and tracking, two chaotic spread spectrum ranging schemes are designed, and their feasibilities, ranging processes, acquisition time and ranging accuracy are analyzed and validated.