Spread Spectrum Modulation and Signal Masking Using Synchronized Chaotic Systems

Chaotic dynamical systems are nonlinear deterministic systems which often exhibit erratic and irregular behavior. The signals that evolve in these systems are typically broadband, noise-like and similar in many respects to a stochastic process. Because of these properties chaotic signals potentially provide an important class of signals which can be utilized in various communications, radar and sonar contexts for masking information-bearing waveforms and as modulating waveforms in spread spectrum systems. Recently, it has been demonstrated that the chaotic Lorenz and Rssler systems can be decomposed into a drive system and a stable response subsystem which will synchronize when coupled with a common drive signal. This property has several practical applications and suggests novel approaches to secure communication and signal masking. In addition to the Lorenz and R6ssler systems, we discuss and demonstrate that the continuous-time Double Scroll system and discrete-time Henon map are also decomposable into synchronizing subsystems. We then propose and explore in a preliminary way how synchronized chaotic systems can be used for spread spectrum communication and for various signal masking purposes.