Small-size ultralow-voltage generator of chaotic microwave oscillations

The scheme of a small-size ultralow-voltage generator of broadband chaotic microwave oscillations is considered. Results of numerical modeling and experimental investigation of the device prototype operating in various regimes are summarized. Good prospects of the proposed ultralow-voltage generator (vircator) are related to the relatively low accelerating voltages (below 1000 V), rather high electron beam currents (up to 800 mA), good efficiency (up to 5%), and small dimensions of the device.     

A novel phase noise measurement of phase modulation microwave photonic links

Abstract

Microwave photonic links can provide many advantages over traditional coaxial due to its low loss, small size, lightweight, large bandwidth and immunity to external interference. In this paper, a novel phase noise measurement system is built, since the input signal and the power supply noise can be effectively cancelled by a two-arm configuration without the phase locking. Using this approach, the phase noise performance of the 10-GHz phase modulation photonic link has been measured for the first time, evaluated the values of ?124 dBc/Hz at 1 kHz offset and ?132 dBc/Hz at 10 kHz offset is obtained. Theoretical analysis on the phase noise measurement system calibration is also discussed.     

Ultralow-voltage generator of chaotic microwave oscillations with secondary-emission cathode

A new scheme of an effective ultralow-voltage generator of broadband chaotic microwave oscillations is considered. The device operates on counterpropagating turbulent electron beams, one of which is created by a secondary-emission cathode. Results of an experimental investigation of the device prototype operating in various regimes are summarized. Promising features of the proposed ultralow-voltage oscillator are the relatively low accelerating voltages (below 500 V), increased efficiency (up to 14–15%) compared to analogs, broad band of generated oscillation frequencies, high level of integral output power (up to 35 W), the possibility of fast and easy control over the generation regimes (from almost monochromatic to broadband), and small dimensions of the device.     

Ultralow-voltage generator of chaotic microwave oscillations on counterpropagating electron beams

Technical Physics Letters - The new scheme of an ultralow-voltage generator of broadband chaotic microwave oscillations is considered, which operates on counterpropagating turbulent electron beams....     

Tunable generator of broadband chaotic microwave oscillations on turbulent electron beams

A new generator of broadband chaotic microwave oscillations of medium power on turbulent electron beams is proposed, in which it is possible to tune the generation regime. The characteristics of turbulent electron beams have been studied by experimental and theoretical methods. It is established that drag of the electron beam produces its turbulization, which leads to the generation of broadband chaotic microwave oscillations.     

Analysis of matching errors in comparison of microwave noise signals

Translated from Izmeritel'naya Tekhnika, No. 11, pp. 52–54, November, 1991.     

Separation of chaotic signals during their incoherent reception using a reference chaos generator

A new scheme of incoherent reception of chaotic radio pulses using a reference chaos generator is described. Analysis of the proposed scheme confirms its performance and efficiency. The scheme exhibits selectivity and can be used for separating pulses generated by several sources.     

Chaotic ultra-wideband radio generator based on an optoelectronic oscillator with a built-in microwave photonic filter

We induce a microwave photonic bandpass filter into an optoelectronic oscillator to generate a chaotic ultra-wideband signal in both the optical and electrical domain. The theoretical analysis and numerical simulation indicate that this system is capable of generating band-limited high-dimensional chaos. Experimental results coincide well with the theoretical prediction and show that the power spectrum of the generated chaotic signal basically meets the Federal Communications Commission indoor mask. The generated chaotic carrier is further intensity modulated by a 10 MHz square wave, and the waveform of the output ultra-wideband signal is measured for demonstrating the chaotic on-off keying modulation.     

Experimental separation of chaotic signals through synchronization

In this paper using a negative feedback scheme we study the problem of synchronizing two systems (each of them made of n independent chaotic circuits) through the transmission of a unique signal (i.e. a scalar variable). To find the appropriate values of the feedback gains, an approach based on the design of an asymptotic observer leading to a set of linear matrix inequalities is used for piecewise linear systems, while for systems with continuous nonlinearities a master stability function approach is adopted. Numerical results showing the suitability of the approach are reported. Furthermore, the experiment showing separation and synchronization of two pairs of chaotic circuits is discussed. Despite the presence of parameter mismatches, separation and synchronization of the two systems can be achieved. This is an experimental demonstration of the successful possibility of multiplexing two (or more) chaotic signals in the same channel.     

A study of noise phenomena in microwave components using an advanced noise measurement system

A novel 9 GHz measurement system with thermal noise limited sensitivity has been developed for studying the fluctuations in passive microwave components. The noise floor of the measurement system is flat at offset frequencies above 1 kHz and equal to -193 dBc/Hz. The developed system is capable of measuring the noise in the quietest microwave components in real time. We discuss the results of phase and amplitude noise measurements in precision voltage controlled phase shifters and attenuators. The first reliable experimental evidences regarding the intrinsic flicker phase noise in microwave isolators are also presented.     

Application of chaotic noise reduction techniques to chaotic data trained by ANN

We propose a novel method of combining artificial neural networks (ANNs) with chaotic noise reduction techniques that captures the metric and dynamic invariants of a chaotic time series, e.g. a time series obtained by iterating the logistic map in chaotic regimes. Our results indicate that while the feedforward neural network is capable of capturing the dynamical and metric invariants of chaotic time series within an error of about 25%, ANNs along with chaotic noise reduction techniques, such as Hammel’s method or the local projective method, can significantly improve these results. This further suggests that the effort on the ANN to train data corresponding to complex structures can be significantly reduced. This technique can be applied in areas like signal processing, data communication, image processing etc.     

Thermal noise generator of the waveguide-coaxial type

Conclusions In comparison with bolometric power transducers the coaxial-waveguide type of TNG that has been described is capable of improving by nearly an order of magnitude the coupling for radio noise emission from a hot fine wire to a waveguide duct. The loss coefficient for it A=1–s₁₁²–s₁₂², varies over the operating range of the waveguide between the limits 0.2–0.3 (for the section 35×15 mm). The proposed method of calculating the parameters for the equivalent circuit of the TNG with losses taken into account can be used to determine the impedance characteristics of practical designs and to optimize their parameters.Translated from Izmeritel'naya Tekhnika, No. 5, p. 69, May, 1980.     

A novel noise figure and gain test set for microwave devices

A new instrument for the measurement of noise and gain of microwave devices is presented. It differs from the commercial ones in the accomplishment of the gain measurement and is also useful for measuring mismatched devices such as transistors, The instrument is driven via HP-IB by a PC and a user-friendly virtual panel is designed to perform all the required operations. Also included is the possibility of removing the second-stage noise contribution and correcting various sources of error (source ENR variations, temperature variations, etc.). The test set provides a very good accuracy for both matched and mismatched devices, usually limited by source ENR accuracy and step attenuator repeatability. The performances of the instrument are compared with those offered by commercial instrumentation     

Generation of single chaotic microwave pulses in a self-oscillating ring system with ferromagnetic film under the action of external noise

The generation of single chaotic microwave pulses in a self-oscillating ring system with ferromagnetic film under the action of external narrow-band noise microwave signal occurring outside the band of frequencies of the chaotic microwave signal was observed. Chaotic generation emerged due to the parametric instability of the magnetostatic surface wave in the ferromagnetic film, whereas formation of single chaotic microwave pulses was caused by the absence of complete suppression of chaos under the action of narrowband noise.     

基于双混沌系统伪随机比特发生器的研究

研究了基于双混沌系统伪随机比特发生器（CCS-PRBG）生成序列的密码学性质,证明了此二进制序列是i.i.d.序列。理论分析表明,CCS-PRBG可生成具有理想保密性的二进制混沌密码序列。     

基于声子晶体的车内噪声研究

声子晶体是近年来提出的一种新型功能材料,是一种由两种或多种材料组成的具有周期性结构和弹性波带隙的声学功能材料或结构,并且振动频率在声子晶体带隙范围内的振动会被抑制或禁止传播,它所具有的这种弹性波带隙特性为汽车车内噪声控制,特别是车内低频噪声控制提供了一种新的研究方法.在介绍了声子晶体的概念、基本特征及能带结构的基础上,阐述了声子晶体在振动与噪声控制领域的研究现状,同时对车内噪声的产生机理进行了分析,最后对声子晶体在应用于汽车车内降噪方面的研究做了展望.