SCIENCE & EDUCATION

The authors investigated the possibility of obtaining a synchronous chaotic response to the signal generated by PLL using extended Kalman filter. The mechanism of onset of chaos in PLL system with 2-nd order astaticism was studied. The domains of stable generation of chaotic signal were obtained. By varying time update equation parameters for various SNR and sampling periods, the quality of signal recovery was investigated by using extended Kalman filter.

The aim of the study was analysis of error probability of direct-sequence spread-spectrum systems under condition of smart jamming and noise in communication channel. The research was based on broadband systems of coherent reception with opposite and orthogonal signals. In the total the authors obtained expressions for definition of error probability at reception of signals depending on the degree of mutual correlation of smart jamming and a useful signal, parity of their powers and noise level in the channel. The results of the research can be used for analyzing and calculating error probability of direct-sequence spread-spectrum systems with smart jamming and noise.

Nowadays progress in laser technology is determined by the progress in laser diode pumping. Modern power supply for diode lasers must provide stable output impulses, suppress reverse current surges and maintain stable temperatures of diode arrays. Inter-channel interference and noise immunity problems arising during generation of current impulses were solved. An automated laser test bench was developed; it included a special microprocessor-based circuit to control operation of the pumping source. A scheme of a temperature maintenance channel was developed along with s special regulation algorithm, which allowed to stable laser radiation at frequencies from 30 to 50 Hz with the longest possible impulse lengths. The developed multi-channel pulse-periodic pumping source for diode bars generates current impulses with frequencies up to 50 Hz and durations between 60 and 500 microseconds. The running current of laser diodes can be as high as 250 Amps. Instability of current from impulse to impulse is lower than 0,5 %. Several implemented protection features (both hardware- and software-based) along with modular design increase reliability of the pumping source. The pumping source was used to conduct experimental researches of new laser quantrons with semiconductor pumping developed at The Radio-electronic Technology Research Institute. The latter experiments resulted in some unique findings.

This article describes a method of increasing the data transmission speed in open optical communication lines, namely the method of increasing the current modulation frequency of a powerful semiconductor laser. In this paper it is shown how the laser case influences the speed of data transmission; the advantage in transmission speed when using the laser in a smaller package is also shown. The authors propose new methods of measurement and calculation of the RLC laser emitter parameters; equations for calculation of the RLC-parameters with known values of the impedance, as well as the calculated values of RLC parameters for two investigated lasers are also given in the article. Quantitative estimations of the influence of RLC parameters on the bandwidth of the laser are included in the conclusion.

The authors present an algorithm of maneuvering targets maintainability; the algorithm uses signal preprocessing data of radar-tracking information for detection of the beginning and the end of the maneuver. Information about the beginning and the end of the maneuver consists in changing the spectrum width of the received signal. The authors propose an algorithm for estimation of spectrum width of the maneuvering target, and study its characteristics. The authors draw a comparison of characteristics of the offered algorithm with a well-known algorithm which uses information about discrepancy between measured and filtered parameters for maneuver detection. Simulation results characterizing efficiency of algorithm are presented. Research methods are: mathematical synthesis and mathematical simulation. Application domain – pulse-Doppler radar stations.

The article describes an algorithm for compensation distortions in sidelobes of a beamformer. Due to using received signal redundancy in frequency domain the algorithm doesn’t need any extra time for adaptation when the signal-distortion situation changes. The algorithm could be applied in multichannel pulse Doppler radars. The research was based on linear algebra and mathematical modeling.

The article considers software implementation and evaluation of properties of one of the classs of nonlinear sequences - GMW sequences for use in CDMA communication systems with code division multiplexing.

Influence of error in modulation index on error performance of a communication system is studied when continuous phase modulation is used. An error performance calculation method is presented in case of modulation index error.

This article considers a satellite navigation signal sequential search algorithm with complex statistics, which is optimal for average search duration minimum criterion in condition of weak signal receipt. Matched filtering in frequency domain, based on Fast Fourier Transform (FFT) is used in order to increase speed of signal acquisition. Signal detection block characteristics are researched in MATLAB. In addition, the considered algorithm and decision algorithm based on Neiman-Pirson criteria are compared.

The authors consider a method of creating ensembles of code sequences obtained on the basis of Legendre sequences, for use in communication systems with ultra wideband signals (UWB).

The aim of this work was the development of adaptive algorithm for antenna array (AA) for side-looking airborne radar; the characteristics of this algorithm were independent of reflection from underlying surface, including that from the main lobe of antenna directivity diagram. Proposed algorithm provided an operation of interference canceler of point sources with intensive reflection from local objects in “review” mode, that is the case of restricted time of radio-locating contact between side-looking airborne radar and target. The following investigation methods were used: mathematical synthesis, mathematical simulation. Application domain was the following: adaptive antenna arrays in side-looking airborne radars.

The new method of estimation of the decision-making process based on usage of heterogeneous information sources is proposed in this article. The results of mathematical simulation of this method are analyzed.

This article deals with the synthesis of clarifying targeting algorithms in radar systems  with millimeter waves and beam antennas, used for detecting low earth orbit satellites. The synthesis of the clarifying algorithm is carried out using the prior information about target trajectory, and also considers the constrained beam movement trajectory of real systems.

The article describes development of multipurpose software package for computer simulation which allows to objectively evaluate the effectiveness of any technical solution used in radars. The authors consider a structural scheme of the developed software and its components and describe the results of a simple simulation.

In this article the results of experimental research works of composing data bank of  radar pictures for different target types in millimeter wave range. The comparative analysis of produced radar pictures depending on angle of the object and wavelength range is included. To solve the detecting and recognizing problems, the possibility of using the oscillating components from Doppler’s images of targets was considered.  

In this article the development of monopulse millimeter wave irradiator is described. This irradiator works with circular polarization of electromagnetic waves and was proposed to be used in receiving and transmitting system with digital four-channel receiver. The main advantages of the developed construction were analyzed; the plan of construction is included.