ABSTRACT
A generic chaotic communications system based on chaotic modulation is shown in Figure 6.1. In such a system, the information bits to be transmitted must first be encoded in the chaotic waveform using the chaotic system’s symbolic dynamics. Rather than using structured signals such as rectangular pulses or sinusoids, to denote “0s” and “1s” (or other information symbols), these communications systems embed the information in the time evolution of the transmitted signal. Regions of the state space formed by the chaotic system’s time evolution are designated to represent different symbols. The process of mapping information bits to the state of a chaotic system through its symbolic dynamics is termed chaotic modulation. This assignment of information bits to state is not arbitrary, and the greatest efficiency is achieved when the information transmission rate matches the topological entropy of the chaotic system.4 Here, the symbolic dynamics representation of a chaotic system is exploited to implement the chaotic modulation described later in Section 6.4.1.
