Journal of the Russian Universities. Radioelectronics / Известия высших учебных заведений России. Радиоэлектроника
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ПЕРЕДАЧА ДВОИЧНЫХ ДАННЫХ НА ХАОТИЧЕСКИ СФОРМИРОВАННЫХ НЕСУЩИХ ЧАСТОТАХ
Get PDFIn this paper, the method of binary data transmission and receiving is first suggested and experimentally investigated. The method uses dynamical chaos as a source of multiple carrier frequencies. On the server side, the transmitter configures informational signal in the form of frequency grid with chaotically varying frequencies of the spectrum with their amplitudes corresponding to transmitted information message. On the client side, the transmitted information is re-stored using chaotically selected spectral windows. Synchronization of the server and client dynamic chaos generators is achieved by means of TCP/IP protocol. Suggested method is based on combined transmission of information message via transmission channel and background signal. Power of background signal significantly exceeds power of informational one. The method allows using different informational signal as a background signal, such as voice message. The addition of low power chaotically formed frequency grid signal does not lead to significant background signal formation either in spectral or in time domain. Thus, the described method allows repeated application of the transmission channel. The effect of signal-to noise ratio of the order of the filter implementing the spectral windows in the receiver and the width of the spectral window is investigated. Signal-to-noise ratio can be reduced with increasing filter order and spectral window width
ПОВЫШЕНИЕ ТЕМПЕРАТУРНОЙ СТАБИЛЬНОСТИ ВЫХОДНОГО НАПРЯЖЕНИЯ ИСТОЧНИКА ПИТАНИЯ ЗА СЧЕТ АНИЗОТРОПНОСТИ ТЕПЛОВОГО ПОЛЯ ЕГО КОНСТРУКЦИИ
Get PDFThe article considers the method of thermal stabilization for precision power supply output voltage by means of anisotropy of the construction thermal field. Interdependency between schematic and design-topological aspects of precision power supply temperature assurance is shown. In theoretical part of the paper, the concept of electronic component local group arranged on isothermal line of the supporting structure plane is introduced. The local group characteristics and conditions for ensuring topological thermocompensation are formulated. The authors propose the solution for two basic applied problems that provides temperature stabilization of electronic devices output parameters by topological temperature compensation using regression analysis. The experimental part of the paper provides the analysis of the output voltage temperature stability for two design versions which differ by availability of topological thermocompensation. The reason of foreign element base use for the purposes of the experimental part of the study is explained. It is shown that the global mathematical model for providing topological thermocompensation for a design option with improved temperature stability is the temperature error equation. A comparative analysis of the two construction options shows 8 % improvement of output voltage temperature stability due to topological thermocompensation. The obtained result may prove to be satisfactory under technical assignment for the use of a different element base and / or other methods of thermal stabilization
К РАЗРАБОТКЕ НОВЫХ МЕТОДОВ АНАЛИТИЧЕСКОЙ ОЦЕНКИ УСТОЙЧИВОСТИ АВТОКОЛЕБАНИЙ В РЕЛЕЙНЫХ ЦЕПЯХ
Get PDFThis article is devoted to the development of analytically described self-oscillation stability research technique. The case when the linear part of the system contains transfer function with a zero pole is considered. Typically the transfer function study, where the numerator degree is two orders of magnitude less than the denominator degree is creates no problems. However, the presence of a zero pole makes the case special and requires investigation.A comparative evaluation of the results of self-oscillation analytical calculation and stability analysis is given, by means of technique developed for symmetric self-oscillations with half-period repetitions and asymmetric ones with period repetitions.The presented technique is a significantly new scientific step in the development of methods for calculating non-linear systems. It also allows us to evaluate the accuracy of approximate calculation methods, which is important for precision systems. The technique is relatively easy to implement. It allows to find a solution as well as for the cases having been unanalyzable so far
ВЛИЯНИЕ ТЕПЛОВОГО БЮДЖЕТА ФОРМИРОВАНИЯ КАНТИЛЕВЕРНЫХ КОНСОЛЕЙ SINX/AL НА НАЧАЛЬНЫЕ ДЕФОРМАЦИИ ТЕПЛОВЫХ СЕНСОРОВ МЭМС
Get PDFMechanical properties of MEMS devices are specified by their structure and process parameters, such as temperature, films thickness, deposition conditions, etc. These features, in particular, the deposition temperature and post deposition treatments, determine the residual stress in the films, which affect the initial deformation, stability of parameters, sensitivity and reliability. Prediction, control and minimization of residual stress are an important part of the structural and technological design of MEMS devices. The effect of post deposition thermal treatment on the residual mechanical stress of SiNx, Al and SiNx/Al films is studied. It is shown that the tensile stress in Al film is critical for residual mechanical stress of the SiNx/Al structure and increases with the increase of temperature and time of post annealing. This allows to control the post annealing conditions and the process temperature budget to compensate the compressive stress in SiNx films and to minimize the summary residual stresses and initial deformations of SiNx/Al structure. The residual stress of the bilayer SiNx/Al structure has little effect on the film thickness, but the ratio of SiNx and Al thicknesses is significant for the thermal deformation of SiNx/Al microcantilever
ОПРЕДЕЛЕНИЕ УРОВНЯ МИКРОВОЛНОВОЙ МОЩНОСТИ, ПЕРЕДАННОЙ В РЕАКТОР, ПО ФОРМЕ АНОДНОГО ТОКА МАГНЕТРОНА
Get PDFAn important task in designing microwave industrial plants is to determine actual power going into a process reactor. A part of magnetron power reflects from the microwave reactor into generator due to the processed material property changes. It results from dielectric property changes, due to changes of temperature, humidity, variation of boundary conditions in the reactor when moving the product. Moreover, the reflected wave significantly changes the magnetron regime of operation. The article shows that the power transferred to the processed product can be determined based on changes in the current pulse form when using a classic power supply (high-voltage transformer and a voltage doubling circuit) and power supply with invertor. Also it is possible to estimate the mutual influence magnetrons on each other in microwave installations with multi generator scheme. The difference in the operation of the classic power supply and inverted power supply leads to necessity for different power determining algorithms. Microwave power in the load determined experimentally coincides with the microwave power calculated by the developed method, which confirms the reasoning of the algorithm used
ПЕЛЕНГОВАНИЕ ИСТОЧНИКОВ РАДИОИЗЛУЧЕНИЯ В ШИРОКОЙ ПОЛОСЕ ЧАСТОТ С ИСПОЛЬЗОВАНИЕМ КРУГОВОЙ АНТЕННОЙ РЕШЕТКИ
Get PDFFor the VHF broadband direction finder, coherent and incoherent direction finding algorithms for switched and non-switched connection of the antenna array (AR) to receiving device in single-signal and multi-signal direction finding modes are developed and investigated.Their synthesis is based on the methods of space-time theory of radio systems. Numerical calculation of the direction finding characteristics of the algorithms for different number of antenna array elements determines the operating range upper limiting frequency, in which this configuration provides single-value estimates of the azimuth and elevation angle. Statistical simulation modeling shows that for an odd number of antennas, the antenna array amplitudephase response is unique in a wider frequency band than for an even number of antennas. Due to this MUSIC based property applied in the space of antenna array elements, direction finding algorithm is developed for wide frequency band with several signals overlapping in frequency, with switched and non-switched AR connection to a radio receiver. It is shown that the use of ESPRIT and MUSIC methods in free-space diagram does not allow for direction finding in a wide frequency band with the antenna array fixed configuration. The results of the field studies of the developed algorithms are presented for the single-signal and multi-signal modes of operation, software and hardware implemented in the VHF radio direction finder. A comparative analysis of the developed algorithms with the known APs with fixed configuration is performed. It is shown that with the same AR configuration, it is the direction finding algorithm that determines the frequency range in which the direction finding is unique
Интерференционный множитель Земли
Get PDFThe article is devoted to the pattern propagation factor of the Earth enabling for more precise determination of the radar station visibility range in case there are reflections from underlying surface. The article provides analytical solution in general form taking into account the Earth sphericity. It enables to obtain the results in the wide-band and altitude range of the observed objects by means of computer simulation. The article gives analytical expression for the Earth multiplier under the flat approximation assumption, free of restrictions common for research literature. Besides, the article defines boundaries in which it is permissible to view the Earth as a flat surface. In addition, the article provides examples to illustrate graphical estimate of the error of all approximations both with respect to the general case of the Earth sphericity and relative to each other.Рассмотрена задача учета интерференционного множителя Земли, позволяющего более точно определить зону видимости радиолокационной станции при наличии отражений от подстилающей поверхности. Представлено аналитическое решение этой задачи в общем виде с учетом сферичности Земли, позволяющее получить результат в широком диапазоне дальностей и высот целей с использованием компьютерного моделирования. Получено аналитическое выражение для множителя Земли в условиях “плоского приближения” без ограничений, обычно встречающихся в литературе. Определены границы допустимости “плоского приближения Земли”. На примерах дается графическая оценка погрешности всех приближений как по отношению к общему случаю сферичности Земли, так и относительно друг друга
Оптимизация итерационных алгоритмов оценки состояния канала связи в системе множественного доступа с разреженным кодированием
Get PDFOptimization of iterative algorithms for channel state estimation in a sparse coding multiple-access system (SCMA) is performed to reduce computational costs of the receiver. It is shown that when a signal-to-noise ratio (SNR) does not exceed 10 dB, one iteration of the algorithm is sufficient, and an increase in the number of iterations does not lead to an increase in spectral efficiency. Simulation demonstrates a possibility of a reasonable choice of the total number of decoder iterations and their distribution between different stages of the channel estimation. For an uncoded system, iterative re-estimation of the channel is proposed, as well as ways to reduce computational costs during its calculation. In the coded system, at a low SNR the achieved spectral efficiency values are approximately similar to those with pilot-only channel estimation. The article provides recommendations for the placement of data symbols and pilot signals in re-source blocks to increase the system spectral efficiency.Проведена оптимизация итерационных алгоритмов оценки состояния канала в системе множественного доступа с разреженным кодированием, направленная на снижение вычислительных затрат приемника. Установлено, что при отношении "сигнал/шум" (ОСШ), меньшем 10 дБ, достаточно одной итерации алгоритма, а увеличение числа итераций не приводит к росту спектральной эффективности (СЭ). Моделирование продемонстрировало возможность обоснованного выбора общего числа итераций декодера и их распределения между различными этапами оценки канала. Для некодированной системы предложена последовательная итерационная переоценка канала, а также способы уменьшения вычислительных затрат при ее выполнении. В кодированной системе при малом ОСШ обеспечиваемые данным алгоритмом параметры СЭ практически не отличаются от параметров метода, в котором для оценки используются только пилот-сигналы. Даны рекомендации по размещению символов данных и пилот-сигналов в блоках ресурсов, позволяющие увеличить СЭ системы
Синтез временно́го дискриминатора следящего контура измерения запаздывания спутникового высотомера
Get PDFThe article considers the design of optimum time discriminator for onboard delay-lock loop of a spacebased radar altimeter. The basic signal model is simplified remaining however adequate enough to the task of keeping echo-signal within the tracking receiver window. Along with the optimal one the quasi-optimal maximum-point and maximal-steepness-point discriminators are proposed. The discriminator curves of all considered structures are calculated. It is shown that the quasi-optimal discrimination yield about 2.5 times to the optimal one in the equivalent time fluctuations. Such a loss can be considered a tolerable cost of achieved hardware simplicity.Проведен синтез оптимального временно́го дискриминатора системы слежения за запаздыванием сигнала бортового приемника спутникового радиовысотомера. За основу принята упрощенная модель эхосигнала, с необходимой адекватностью отвечающая режиму удержания сигнала в следящем окне приемника. Наряду с оптимальным предложены квазиоптимальные дискриминаторы точки максимума принимаемой мощности и точки максимальной крутизны. Рассчитаны дискриминационные характеристики рассмотренных структур; показано, что квазиоптимальные дискриминаторы примерно в 2.5 раза уступают оптимальному в размахе эквивалентных флюктуаций запаздывания, что можно считать умеренной ценой достигнутых упрощений в реализации дискриминатора