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The chaotic systems are among the most important areas that have increased in popularity and are actively used in several fields. One of the most essential components in chaotic systems is the chaotic oscillator which generates chaotic signals. IQ-Math and floating point number systems are preferred number standards. In this study, the Modified Chua chaotic oscillator has been designed to work on FPGA chips using fixed point and floating point number representations, and both system version performances are compared. Euler numeric algorithm has been used to design the Modified Chua chaotic oscillator. In the first section of the study, the Modified Chua chaotic system based on fixed point has been composed the model in the Matlab Simulink and converted to VHDL with the help of Matlab HDL Coder Toolbox. In the second section of the study, the Modified Chua chaotic oscillator has been designed with VHDL based on floating point. Modified Chua chaotic oscillators which are composed with two different number standards have been tested using Xilinx ISE Design Tools in VHDL. Modified Chua chaotic oscillators which have two different number standards and designed, are synthesized for Virtex-6 on ML605 FPGA development board using Xilinx ISE Design Tools 14.2 program. The values that are achieved from the process of synthesizing and the process of maximum operating frequency have been presented. As a result, the study has found that fixed-point representation achieved a maximum operating frequency of 50.242 MHz, while the floating-point representation achieved 273.631 MHz. [ABSTRACT FROM AUTHOR]

A new algorithm is described for detecting hidden changes in the topological structure of the dynamics of a nonlinear system due to the perturbations in the driving signals. The proposed method is based on the use of a double sliding window and wavelet decomposition and calculates the Jensen–Shannon divergence between the probability distributions of the normalised wavelet coefficients of the first half of the sliding window and those of the second half of the sliding window. Applying the proposed approach to the Duffing and Hénon–Heiles systems, real-life signals showed their effectiveness at detecting small discontinuities in the dynamic behaviour of the system even when the system is chaotic. [ABSTRACT FROM AUTHOR]

This scientific study reports on the practical as well as modelling of active hybrid inductor based chaotic oscillators using Current Feedback Amplifier (CFOA) and Op-Amp. Furthermore, a workable design strategy for the chaotic oscillator and its application to secure communication are provided. Here, the transient analysis of chaos waveforms is verified by using MATLAB, Multi-SIM, and LT-Spice tools. The numerical outcomes based on LT-Spice and MATLAB are closely matched. Additionally, results from the multi-SIM platform show how a secure communication network was implemented utilising the master-slave technique of synchronisation. Finally, a comparison analysis is conducted to demonstrate the originality of the suggested work.

Over the past years, many chaos-based secure communication system algorithms have been published for the encryption of different types of data. The problem with these algorithms is either the high complexity that makes them difficult to be implemented or the lack of the high security that prevents them from being applicable in real applications. In this paper, we propose a new highly-secured chaos-based communication system that is based on adaptive control synchronization. The implementation process of the proposed system is detailed including the oscillator dynamic equations, the control laws derivation, the numerical solutions, and the Matlab/Simulink representation. To show the efficiency of the proposed system, its security is analyzed using different security measures. This proofs that the carrier signal is unpredictable by the intruder in both time and frequency domains. The experimental results and the show that the proposed system outperforms the different related and recent work in addition to its stability and robustness to the variation of initial conditions. Finally, we introduce an application on voice encryption to demonstrate the effectiveness of our system. Then We compare the security results of our system with different implementations of recent and related work. [ABSTRACT FROM AUTHOR]

The paper is dedicated to the numerical and experimental study of nonlinear oscillations exhibited by the Vilnius chaotic generator. The motivation for the work is defined by the need for a comprehensive analysis of the dynamics of the oscillators being embedded into chaotic communication systems. These generators should provide low-power operation while ensuring the robustness of the chaotic oscillations, insusceptible to parameter variations and noise. The work focuses on the investigation of the dependence of nonlinear dynamics of the Vilnius oscillator on the operating voltage and component parameter changes. The paper shows that the application of the Method of Complete Bifurcation Groups reveals the complex smooth and non-smooth bifurcation structures, forming regions of robust chaotic oscillations. The novel tool—mode transition graph—is presented, allowing the comparison of experimental and numerical results. The paper demonstrates the applicability of the Vilnius oscillator for the generation of robust chaos, and highlights the need for further investigation of the inherent trade-off between energy efficiency and robustness of the obtained oscillations. [ABSTRACT FROM AUTHOR]

The measurement of bio-impedance spectra at ultra low frequencies (sub-Hz) is known to require a considerably long time with the classical frequency-sweep method or other narrow-band periodic excitation signals. In this work, an impedance measurement technique based on using wide-band chaotic signals is proposed and experimentally validated over the frequency range 10 m H z - 1 H z . The technique was tested in both potentiostatic and galvanostatic modes, first using commercial components and then using an enhanced Howland current pump designed and fabricated in a 65nm CMOS technology. The accuracy of the proposed technique was assessed on fruit samples compared to measurements conducted using a research-grade Biologic VSP-300 electro-chemical station. [ABSTRACT FROM AUTHOR]

This paper strives to achieve a comprehensive review of chaos in analog circuits and lumped electronic networks. Readers will be guided from the beginning of the investigations of simple electronic circuits to the current trends in the research into chaos. The author tries to provide the key references related to this issue, including papers describing modern numerical algorithms capable of localizing chaotic and hyperchaotic motion in complex mathematical models, interesting full on-chip implementations of chaotic systems, possible practical applications of entropic signals, fractional-order chaotic systems and chaotic oscillators with mem-elements. [ABSTRACT FROM AUTHOR]

This paper strives to achieve a comprehensive review of chaos in analog circuits and lumped electronic networks. Readers will be guided from the beginning of the investigations of simple electronic circuits to the current trends in the research into chaos. The author tries to provide the key references related to this issue, including papers describing modern numerical algorithms capable of localizing chaotic and hyperchaotic motion in complex mathematical models, interesting full on-chip implementations of chaotic systems, possible practical applications of entropic signals, fractional-order chaotic systems and chaotic oscillators with mem-elements.