E. V. Efremova

QUALITATIVE THEORY OF DYNAMICAL SYSTEMS, CHAOS AND CONTEMPORARY WIRELESS COMMUNICATIONS

This paper shows how the qualitative theory of dynamical systems, that is intensively developed during the last forty years, is currently applied in practice to provide effective wireless ultrawideband communications using chaotic information carrier.

Separation of chaotic signal sum into components in the presence of noise

The problem of separation of an observed sum of chaotic signals into the individual components is considered in the presence of noise. A noise threshold is found above which high-quality separation is impossible. This effect is shown to be associated with the information content of chaotic signals and a theoretical estimate is given for the threshold. A method for signal separation is proposed, which uses iteration of the chaotic source equations in reverse time. The method allows us to approach the theoretical limit threshold.

A microwave chaos generator with a flat envelope of the power spectrum in the range of 3–8 GHz

A promising type of ultrawideband (UWB) signals for communications and radar techniques operating in an unlicensed frequency range of 3.1–10.6 GHz, which has been actively developed in recent years, is offered by chaotic oscillations. We have designed and studied a chaotic oscillator with a uniform distribution of spectral power density in the range of 3–8 GHz. The possibility of using these oscillators in multiband UWB communication systems and noise generators for radio-engineering measurements is discussed.

Chaotic signal processing: information aspects

Abstract One of the features of chaotic signals that make them different of other types of signals is their special information properties. In this paper, we investigate the effect of these properties on the procedures of chaotic signal processing. On examples of cleaning chaotic signals off noise, chaotic synchronization and separation of chaotic signals we demonstrate the existence of basic limits imposed by information theory on chaotic signal processing, independent of concrete algorithms. Relations of these limits with the Second law, Shannon theorems and Landauer principle are discussed.

Dynamic chaos in the microwave range generated in SiGe-based autooscillatory structure

A chaotic microwave autooscillatory structure has been designed, implemented on a monolithic IC manufactured by 0.25-μm silicon-germanium technology, and studied. The experiments with the IC showed the possibility of generating stable chaotic oscillations in the 3–8-GHz range.

Radio lighting based on ultrawideband dynamic chaos generators

The problem concerned with lighting of objects and surfaces by means of artificial incoherent microwave sources is considered with the aim of their subsequent observation with the help of radiometric equipment. Transmitters based on dynamic chaos generators are used as wideband incoherent microwave emission devices. The experimental sample of the given device, namely, radio light lamp based on the chaos microgenerator, and its characteristics are described.

Multimedia sensor networks based on ultrawideband chaotic radio pulses

The requirements to transceivers, which are intended for multimedia data transmission in wireless sensor networks, and existing system characteristics are discussed. Ultrawideband wireless systems based on direct chaotic data transmission are analyzed to reveal the prospects of their application to multimedia sensor networks. The results obtained during experimental studies into video data-flow transfer, which are performed in the point-to-point mode with the use of radio relaying and through-wall transmission, are presented.

Generating dynamic microwave chaos in self-oscillating ring system based on complementary metal-oxide-semiconductor structure

We have designed, implemented, and studied a chaotic self-oscillating system based on a monolithic integrated circuit on a silicon substrate. Experimental prototypes demonstrated stable generation of chaotic microwave oscillations with a maximum spectral power density in a frequency range of 2.8–3.8 GHz.

FORMING PULSES IN NONAUTONOMOUS CHAOTIC OSCILLATOR

In this work we demonstrate a possibility of generating chaotic pulses by means of parameter modulation of chaotic oscillator. Chaotic oscillator with 2.5 degrees of freedom and transistor as an active element is taken as a model. It is shown that periodic stimulation of such system allows to generate chaotic pulse stream, the duration of chaotic pulses and their duty cycle can be widely varied by suitable choice of frequency of the exciting force and bias voltage.

Multiplexing chaotic signals in the presence of noise

In this report we discuss the problem of separating the sum of chaotic signals into the individual components with a procedure of backward iteration of the mapping equations describing the chaotic sources. We show that the proposed approach has good stability in respect to additive external noise.