Synchronisation of hyperchaotic oscillators

The authors present three different examples demonstrating the possibility of synchronising hyperchaotic oscillators via a single variable     

Driving nonlinear resonator with hyperchaotic signals

The response of a fourth-order nonlinear resonator to signals from a hyperchaotic oscillator is described. The resonator represents a replica of part of the driving oscillator. The resonance response to hyperchaotic signals is shown to be achieved via a single driving variable     

Simple 4D chaotic oscillator

An extremely simple 4D chaotic oscillator is presented. It contains a single op amp, two LC circuits and a diode used as a nonlinear device. The chaotic oscillations have been characterised using the correlation dimension of the strange attractor, the Lyapunov exponents and the Lyapunov dimension. The dimensions are found to be >3     

Experimental demonstration of chaos from Colpitts oscillator in VHF and UHF ranges

Experimental results demonstrating chaotic performance of the Colpitts oscillator in the very high frequency (30-300 MHz) and the ultra-high frequency (300-1000 MHz) ranges are reported. Period-doubling route to chaos is revealed, confirming the dynamical nature of the chaotic oscillations. Broadband continuous power spectra are presented.     

The smallest transistor-based nonautonomous chaotic circuit

A nonautonomous chaotic circuit based on one transistor, two capacitors, and two resistors is described. The mechanism behind the chaotic performance is based on "disturbance of integration". The forward part and the reverse part of the bipolar transistor are "fighting" about the charging of a capacitor. Measurements and PSpice experiments are presented.     

Reproducible analogue circuit for chaotic synchronisation

A highly reproducible analogue oscillator has been designed for chaotic synchronisation and secure communication. The oscillator contains a negative impedance converter, an LC resonance loop, an RC phase shift circuit, and a comparator chip used as a nonlinear device     

Two-stage chaotic Colpitts oscillator

A novel version of the chaotic Colpitts oscillator is proposed. It contains two bipolar junction transistors coupled in series. The resonance loop consists of an inductor and three capacitors. The two-stage oscillator, compared with the classical circuit, enables the fundamental frequency of chaotic oscillations to be increased by a factor of three. The PSpice simulations performed with 9 GHz threshold frequency transistors demonstrate that the highest fundamental frequencies of chaotic behaviour are 1 and 3 GHz for the classical and the two-stage Colpitts oscillator, respectively     

Delayed feedback chaotic oscillator with improved spectral characteristics

A chaotic oscillator, including a nonlinear unit, an amplifier, an RC filter and a delay line, is described. Depending on the gain the circuit exhibits mono- or two-scroll chaotic oscillations. The two-scroll oscillations, in comparison with the mono-scroll oscillations, are characterised by three times higher fundamental frequency.     

Double scroll in a simple `2D' chaotic oscillator

A very simple RC oscillator exhibiting the double-scroll chaotic attractor is described. The circuit contains two opamps, a Wien bridge, and two diodes used as nonlinear devices. The typical waveforms and the phase portraits of the attractor are presented to illustrate the double scroll in a quasi-two-dimensional oscillator     

Improved chaotic Colpitts oscillator for ultrahigh frequencies

A novel version of the Colpitts oscillator is presented generating chaotic oscillations at gigahertz frequencies. In contrast to the standard oscillator the inductor is moved from the collector circuit of the transistor to the base circuit. PSpice simulations demonstrate chaos at the fundamental frequencies of 0.5, 1 and 2 GHz employing transistors with a threshold frequency of 9 GHz.