Items of № 8, 2013

The Electrosvyaz Magazine is one of the leading science & technical magazines in Russia.

MIKHEENKO A.M., ABRAMOVA E.S., ABRAMOV S.S.

Increasing the stability of the pulse-width system with negative feedback

Pulse-width system (SIS) are used in automatic control (control), as well as in power amplifiers class «D» with an intermediate pulse-width modulation, covered by a negative feedback to reduce distortion. Feedback into the SIS is inevitably linked with the problem of sustainability. The solution to this problem, a suitable form for the practical application of SIS in general does not exist. This paper presents the results of a study of pulse-width system (SIS), covered by a chain of negative feedback (NFB). On the basis of the asymptotic method of reducing the order of the linear part of the system, the technique of the SIS data to an equivalent non-linear pulse-amplitude system (AIS), for which we can apply the known methods. Used in the method of approximate calculation of transients proposed by Y.S. Itskhoki will greatly simplify the task of analyzing the stability of pulse-width system, even in the case of a high order of its linearity. Key words: pulse-width system (SIS), negative feedback (NFB), power amplifier, asymptotic method.


 

SAZHNEV A.M., GUBKINA V.R., SALAMONOV A.E.

Power supply of light-emitting diodes in optical communication devices

We solve the problem of testing the operation of the device active protection against over-voltage light-emitting diodes used in optical communication devices by means of simulation modeling in OrCAD. The results showed that a fixed duty ratio at 0.5 provides a smooth change of the current light-emitting diodes incorporating a range that reduces the level of over-voltage and current surges, reduces the transition process and eliminates the need for a parallel connection of passive restraints (resistors or varistors). This leads to increased reliability and efficiency. In addition, the proposed device has a high speed determined by speed of modern digital circuits.
Key words: simulation modeling, device active protection, over-voltage, physical processes.


 

LYAMIN N.V., KLEYKO D.V., MELENTJEV O.G.

Low complexity equations for calculation of probability of frame failing in discrete channel

The paper introduces precise equations for accounting the probability of appearance m errors into the block of n elements length P(m,n) in case when number of errors are varied in range 1 to 7 while infinite block length. Moreover general-purpose algorithm for construction those equations is described. Proposed equation give accurate results for P(m,n) computations while number of necessary arithmetical operations lower than in case of using known methods.
Key words: probability of frame failing, Markov’s chain, amount of operations, vector of states.


 

BIKMETOV R.F., ZASLAVSKY K.E.

The analysis of hybrid fiber optical transmission system

The article offers a research of baseband transmission path of fiber optics transmission system with OTDM which established on application of modern fiber optics technologies. The transmission principle which has been investigated is represented as an alternative method to widespread transmission systems with wavelength division multiplexing (WDM). The goal of our research is improvement of engineering-and-economical performance existing high-speed optical transmission systems.
Key words: optical transmission systems with time division multiplexing, baseband transmission path, signal-noise ratio.


GUSTCHIN A.S., KIRJANOV A.G., LYAKHOV A.I., KHOROV E.M.

Fast quality estimation for video streaming in lossy networks

Analyzing the ability of networking protocols to stream real-time video data, many researchers are faced to the problem of video quality estimation, for which the MSE and SSIM metrics are widely used. However, these metrics do not take into account packet losses inevitable with video streaming over wireless networks and fail to estimate the quality of the received video if some frames are lost. To adapt video quality metrics for this scenario, several methods matching video frames of two video samples have been developed. Estimation the similarity of each frame of the received video with a number of frames of the original one takes much time, which limits the application of these methods. The paper proposes a novel frame matching method allowing to speed up greatly video quality metric estimation.
Key words: lossy networks, MPEG-4, MSE, video frame matching, video quality assessment, video quality metric.


 

VORONOVICH V.V., POTAPOV A.Y., ROGOV N.V.

Energy characteristics of the inverse class F amplifier with a limited number of harmonics

In this study, the energy characteristics of the inverse class-F amplifier are obtained in the normalized (generalized) form, depending on the parameters of its schemes by limiting the number of harmonics involved in the formation of high-performance mode. Found that with the same output power and the presence of losses in the active element of the investigated amplifier, the efficiency is higher than the efficiency of the class-F amplifier and other amplifiers. The simulation results and experimental results show the feasibility of studding and implementation of the inverse class-F amplifiers as a facilities of improving the energy characteristics of radio transmitters.
Key words: inverse class-F amplifier, energy characteristics.


 

PROTOPOPOV L.N.

Possibility of modulator bandwidth requirements abatement in polar modulation transmitters (Kahn technique)

The paper addresses spectrum shaping features in polar modulation transmitters. It has been shown that by means of signal correction in the phase component amplification channel there can be achieved distortion compensation caused by modulator bandwidth limitation. The possibility of this correction technique implementation is considered using the OFDM mathematical model.
Key words: polar modulation transmitter, polar modulation oscillation correction, OFDM system modeling.


 

SAMSONOV M.Yu., GREBESHKOV A.Yu., ROSLYAKOV A.V., VANYASHIN S.V.

Internet of things standardization


 

SHORIN A.O.

Probability of providing connections refusals in cellular communication systems taking into account subscribers mobility and a signal fading

 

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