Optimization of the Cascade Code Parameters by the Criterion of the Boundary Value of the Interference Band and the Selection of the Decoding Algorithm

Рассмотрен когерентный канал передачи данных с псевдослучайной перестройкой рабочей частоты (ППРЧ), каскадным кодом на основе ансамбля ортогональных сигналов и кода Рида-Соломона, с различными алгоритмами приема-декодирования в условиях одновременного действия на канал двух помех – заградительной и сосредоточенной в части полосы ППРЧ. Получены оценки граничного значения части полосы ППРЧ, накрытой помехой, характеристики оптимального каскадного кода, а также выбран алгоритм приема-декодирования, при котором граничное значение части полосы, накрытой помехой, принимает максимальное значение в заданной помеховой обстановкеA coherent data transmission channel with pseudo-random tuning of the operating frequency (FH) is considered, a concatenated code based on an ensemble of orthogonal signals and a Reed-Solomon code, with various reception-decoding algorithms under conditions of simultaneous action on the channel of two interference – a barrage and a FH concentrated in a part of the band. The estimates of the boundary value of the part of the FH band covered by the interference, the characteristics of the optimal concatenated code, are obtained, and also the receive-decoding algorithm is selected, in which the boundary value of the part of the band covered by the interference takes the maximum value in a given interference environmen

A Generalized Technique for Studying the Information Properties of Channels and Recognition Systems

В работе предложена обобщённая методика исследования информационных свойств каналов и систем распознавания, применимая для анализа комплексных систем распознавания. Применение методики показало, что при объединении разнородных каналов для распознавания эффективно использование не только прямой, но и косвенной информации о принадлежности объекта к классам в алфавите окончательных (общих) решений. Объединение каналов с основной и косвенной информацией увеличило количество получаемой информации на 10–40 %The paper proposes a generalized methodology for studying the information properties of channels and recognition systems, applicable to the analysis of complex recognition systems. The application of the technique showed that when combining heterogeneous channels for recognition, it is effective to use not only direct, but also indirect information about the object’s belonging to classes in the alphabet of final (general) solutions. Combining channels with basic and indirect information increased the amount of information received by 10–40 percen

Jamming Resistance of the Inbound Channel of an Identification System with Broadband Signals and Error Control Codes in the Conditions of Pulse Noise and Intra-System Jamming

Приводятся результаты оценки помехоустойчивости запросного канала радиолокационного опознавания с широкополосными сигналами в условиях импульсных шумовых и внутрисистемных помех. Определяются оптимальные сигнально-кодовые конструкции ортогональных широкополосных сигналов с корректирующими кодами Рида-Соломона для различных характеристик воздействующих помехResults of an assessment of a noise stability of the request channel of a radar-tracking identification with broadband signals in the conditions of pulse noise and intersystem hindrances are given. Optimum alarm and code designs of orthogonal broadband signals decide on Read-Solomon’s correcting codes for various characteristics of influencing hindrance

Characteristics of Strobeless Identification of Trajectories of Air Objects in Positioning and Radar Identification

Представлены характеристики отождествления данных специального (военного) автоматического зависимого и радиолокационного наблюдений воздушных объектов при их координатно-связном опознавании. Характеристики получены в результате статистического имитационного моделирования алгоритма бесстробового отождествления траекторий, синтезированного по методу, основанному на теории оптимальной фильтрации дискретно-непрерывных марковских случайных процессов. Выполнено сравнение этих характеристик с характеристиками бесстробового и стробового отождествлений при радиолокационном опознаванииThe characteristics of identification of data of special (military) automatic dependent and radar observations of air objects during their coordinate-connected identification are presented. The characteristics are obtained as a result of statistical simulation of the algorithm for strobeless identification of trajectories, synthesized by a method based on the theory of optimal filtering of discrete-continuous Markov random processes. These characteristics are compared with the characteristics of strobeless and strobe identification in radar identificatio

Immunity of the Data Transmission Channel with FHSS when Soft Decoding by Means of Spectral Density Estimation of Interference Power

Получены характеристики помехоустойчивости когерентного канала передачи данных с псевдослучайной перестройкой рабочей частоты (ППРЧ), ортогональными сигналами и кодом Рида-Соломона при его мягком декодировании с использованием оценок спектральной плотности мощности помехи, представляющей собой совокупность двух гауссовских шумовых помех – заградительной и сосредоточенной в части полосы ППРЧ. Установлено, что при увеличении объема ансамбля ортогональных сигналов помехоустойчивость повышается за счет повышения точности оценки спектральной плотности мощности помехи, что в свою очередь обеспечивает повышение точности оценки апостериорной вероятности, используемой при декодировании мягких решенийThe characteristics of noise immunity of a coherent data transmission channel with Frequency Hopping Spread Spectrum (FHSS), orthogonal signals and Reed-Solomon code with its soft decoding have been obtained using spectral density estimation of interference power, which is a combination of two Gaussian noise interference, they are barrage jamming and one concentrated in the FHSS band part. It is found that when the volume of an orthogonal signals ensemble increases, noise immunity rises due to the accuracy growth of the spectral density estimation of the interference power, which in turn provides an accuracy growth of posterior probability estimation used for soft-decision decodin

Structure and electrical properties of zinc oxide base iron doped ceramics

The search for new economically advantageous technologies of new zinc oxide based composite ceramic materials and the study of their structure and properties attract special attention today. These ceramics have a number of advantages as compared with materials prepared by more expensive technologies, due to the possibility to fabricate items having different shapes and sizes and particularly to vary their morphology, structure and phase composition. This allows controlling their functional properties by varying the powder particle size in charge, the temperatures, durations and atmospheres of synthesis and heat treatment, and the types of doping impurities in the ceramics. The structure and electrical properties of (FexOy)10(ZnO)90 ceramics (0 ≤ x ≤ 3; 1 ≤ y ≤ 4) synthesized in air using single- and two-stage synthesis methods have been studied. FeO, α-Fe2O3 and Fe3O4 powders or (α-Fe2O3 + FeO) mixture have been used for ZnO doping. X-ray diffraction, gamma-ray resonance spectroscopy and Raman spectroscopy data suggest that at average iron concentrations of 1–3 at.% the ceramic specimens contain at least three phases: the Zn1-δFeδO solid solution with a wurtzite structure, the ZnFe2O4 ferrite phase with a spinel structure and FexOy residual iron oxides which were used as doping impurities. Scanning electron microscopy and energy dispersion X-ray analysis have shown that the wurtzite phase grain size in the ceramic specimens decreases from several decades of microns for single-stage synthesis to submicron sizes for two- stage synthesis. We show that iron addition to ZnO induces a compression of the wurtzite phase crystal lattice, the compression of lattice magnitude being proportional to the oxygen content in the FexOy iron oxide doping agent. The temperature dependences of the electrical resistivity suggest that deep donor centers with an activation energy of about 0.37 eV are formed in the Zn1-δFeδO wurtzite phase. The temperature dependences of the electrical resistivity of electrons for undoped ZnO in the 6–300 K range and for doped (FeO)10(ZnO)90 ceramic synthesized in one stage exhibit a variable activation energy below 50 K which indicates a heavily disordered structure

Estimation of Parameters of Signal Mixture with Noise Based on Monitoring Outputs of the Multichannel Device of Orthogonal Signals Distinction at Coherent Reception

Получены математические выражения для оптимальных и квазиоптимальных оценок отношения сигнал/шум и спектральной плотности мощности шума, формируемых по наблюдению выходов когерентного многоканального устройства различения ортогональных сигналов. Установлено, что, обрабатывая выходы каналов в многоканальных устройствах различения ортогональных сигналов, можно формировать практически реализуемые квазиоптимальные оценки отношения сигнал/шум или параметров шума с достаточно высокой точностьюMathematical expressions for optimal and quasi-optimal estimations of signal/noise relation and spectral density of noise capacity, based on monitoring outputs of the coherent multichannel device of distinction of orthogonal signals have been received. It was found that, by means of processing outputs of channels in multichannel devices of distinction of orthogonal signals, one can make almost implementable quasi-optimal estimations of signal/noise relation or noise parameters with rather high accurac

Thermal and thermoelectric properties of metal-doped zinc oxide ceramics

The thermal, electrical and thermoelectric properties of ZnO–MexOy ceramics with 1 ≤ x, y ≤ 3, where Me = Al, Co, Fe, Ni, Ti, have been studied. The specimens have been synthesized using the ceramic sintering technology from two or more oxides in an open atmosphere with annealing temperature and time variation. The structural and phase data on the ceramics have shown that post-synthesis addition of MexOy doping powders to wurtzite-structured ZnO powder causes Znx (Mе)yO4 spinel-like second phase precipitation and a 4-fold growth of ceramics porosity. Room temperature heat conductivity studies have testified to predominant lattice contribution. A decrease in the heat conductivity upon doping proves to be caused by phonon scattering intensification due to the following factors: size factor upon zinc ion substitution in the ZnO lattice (wurtzite) by MexOy doping oxide metal ions; defect formation, i.e., point defects, grain boundaries (microstructure refinement); porosity growth (density decline); secondary phase particle nucleation (Znx (Mе)yO4 spinel-like ones). The above listed factors entailed by zinc ion substitution for metal ions (Co, Al, Ti, Ni, Fe) increase the figure-of-merit ZT by four orders of magnitude (due to a decrease in the electrical resistivity and heat conductivity coupled with a moderate thermo-emf decline). The decrease in the electrical resistivity originates from a more homogeneous distribution of doping metal ions in the wurtzite lattice upon longer annealing which increases the number of donor centers

New Efficient Organic Scintillators Derived from Pyrazoline

We report on the synthesis, spectroscopic and scintillation properties of three new pyrazoline core based fluorophores. Fluorescence properties of the fluorophores have been studied both in a solution state and in a solid polyvinyltoluene (PVT) resin matrix of different porosity. The synthesized fluorophores were found to be promising candidates for application in plastic scintillators for detection of ionizing radiation (alpha, beta particles, γ rays and neutrons) and demonstrated superior efficiency in comparison to the existing commercially used fluorophores (2-(1-naphthyl)-5-phenyloxazole (αNPO), 9,10-diphenylanthracene, etc.). Moreover, the suggested synthetic route allows functionalization of the fluorophores with a vinyl group for further covalent bound to the PVT or other vinyl polymer matrices, which dramatically improves chemical stability of the system simultaneously improving the photoluminescence quantum yield. Possible mechanisms of the enhanced scintillation properties are discussed based on preliminary quantum mechanical calculations and spectroscopic characteristics of the fluorophores under study

Evolution and Interdependence of Structure and Properties of Nanocomposites of Multiwall Carbon Nanotubes with Polyaniline

Structure–property relationships of nanocomposites of multiwall carbon nanotubes (MWCNTs) and polyaniline (PANI) doped with dodecylbenzenesulfonic acid (DBSA) are studied and discussed in terms of contribution of the PANI phase properties. Two phases of PANI-DBSA with different properties, such as a shell-wrapping carbon nanotube and separate neat PANI-DBSA domains, are revealed for the first time in the nanocomposites with a high or medium PANI-DBSA content. In the nanocomposites with lower PANI-DBSA contents (<40 wt %), only a core–shell morphology with ∼3 nm or lower thickness PANI shell on the nanotubes is observed. Under this condition, the degree of crystallinity of the PANI-DBSA shell increases almost 2-fold, and thermal stability of the nanocomposite grows sharply. As compared with the neat PANI-DBSA, this special PANI shell phase has more perfect molecular structure and is characterized by a reduced amount of DBSA. It is found that the latter is caused by a competition between the processes of doping of the formed PANI in the shell by the protonic acid and p-doping caused by the MWCNT surface. The nanocomposites demonstrate ppm/ppb range sensitivity to ammonia/methylamine gases with response times, which inversely depend on the PANI-DBSA contents and thickness of the shell