Design and implementation of the Sprott chaotic secure digital communication systems

In this paper, synchronization of Sprott chaotic systems and its application in secure communication are presented. We first utilize a proportional-integral-derivative (PID) control scheme to solve the synchronization problem of chaotic systems. Then for the purpose of application to secure communication, a state signal of the analog chaotic system is converted to a digital train with variable pulse width (square wave with random frequency) by voltage controlled oscillator (VCO). The original digital message is masked by the digital train generated from VCO in the chaotic transmitter via a logical exclusive-OR (XOR) operation and it can be successfully recovered by another VCO and XOR operation at the chaotic receiver due to the synchronization. To verify the system performance, basic electronic components containing operational amplifiers (OPAs), resistors and capacitors are used to implement the proposed PID-based chaotic secure communication system. Finally, the experimental results validate the proposed chaotic communication approach. (C) 2012 Elsevier Inc. All rights reserved.