Synchronization Error Investigation of an Autonomous Chaotic System in Signal Masking Application

Objectives: In recent years signal masking application is very popular and lot of work has been published. Most of the work suggested that to maintain synchronization between transmitter and receiver, amplitude of the message signal should be low keeping the frequency constant. The objective of this paper is to investigate the measurement of synchronization error between coupled transmitter and receiver. The paper shows how synchronization error varies with the changing amplitude and frequency of the encrypted message signal. Methods: The system taken in this work is described by ordinary differential equations and implemented with simple electronic components. The transmitter and receiver system are identical and coupled through a reference signal. When message signal is added to the chaotic signal, synchronization error occurs which effects the exact recovery of the message signals at receiver. Synchronization error has been calculated by keeping the frequency constant and varying the amplitude of the message signal and vice versa. An improved synchronization scheme with feedback is also implemented to see the effect of feedback on synchronization of coupled chaotic systems. Findings: These works gives more insight into signal masking application and conclude that the encrypted signal amplitude should be as low as possible for better synchronization and its frequency should be kept high. If feedback is used masking will be better and synchronization error is reduced because now the dynamics of transmitter is also change in accordance with the receiver. With feedback scheme the error is constant for the range of frequencies and message signal amplitude. Applications: The feedback scheme is useful for those signals which have changing amplitude or changing frequency. It has been observed that the synchronization error reduces considerably in case of improved synchronization scheme with feedback. This work can also be extended for masking digital signals.