The data on the development and study of silica hollow-core microstructured fibers, the principle of operation of which is based on the phenomenon of antiresonant reflection of light, are given. For an optical element with a core of 46 μm in diameter, formed by six non-touching capillaries with a diameter of 20 µm and wall thickness of 2,8 μm, the existence of at least four regions of signal transmission in the wavelength range from 1 to 4 μm has been found. Using the results of numerical simulation and experimental data, it was shown that the obtained fiber is characterized by a practically single-mode mode operation with an effective mode field area of about 1000 μm2, due to the large attenuation level of the group of higher-order modes.

In the fourth part of the paper, a theoretical study of the processes of propagation of pulses having the form of Gaussian functions and hyperbolic secant on a single-mode optical fibers with alternating signs of group velocity dispersions and taking into account losses was performed. Fundamental inaccuracies in widely used expressions to describe the processes of propagation of Gaussian pulses through optical fibers are revealed and refined analytical expressions are proposed. The paper contains a simulation of optical fiber communication systems at speeds of 10 and 40 Gbit/s using the OptiSystem and AltPhotonic Simulation Tool programs. The influence of the chirping value on the quality of communication is investigated. A comparison of fiber-optic communication systems using concentrated and distributed optical amplifiers is performed. Engineering formulas and recommendations for designing quasi-soliton optical fiber communication systems are proposed.

The paper presents author’s original method of hardware synthesizers and sound processing devices modeling, taking the Yamaha TX81Z FM synthesizer as an example. The computer music language called Csound is used for the software simulation. The paper gives the basis of FM synthesis theory, the review of modeling method, and analysis of modeling results.

The two most noticeable types of distortion in an audio signal path - frequency and nonlinear - are frequently analyzed by researchers and developers in terms of auditory perception. The effect of transient distortion, though insufficiently studied, is evident in subjective listening tests when comparing dynamic transducers with similar frequency response and no audible nonlinear distortions. In the present study was conducted dynamic transducer measurements and subjective evaluations to define the critical factors based on the dynamic transducer’s electromechanical characteristics that affect transient distortion and determined relations between the factors’ values and subjective scores.

The analysis of the possibility of building a system for identifying devices of the Internet of Things based on the Digital Object Architecture has been carried out. A model of the system of resolution handle system of Digital Object Identification as a queuing system is proposed. The analysis of the existing system Handling. Is proposed an identification system model based on digital object architecture. On the basis of the developed model of the queuing system, an optimization experiment was performed and the configuration of the resolution system was obtained, allowing to reduce the time for resolving the device identifier. The software of the existing Handle System resolution was analyzed and ways of improving the algorithms with the aim of reducing the time for identifier resolution were proposed. Keywords: Internet of Things, Digital Object Architecture, Digital Object Identification, Handle System, queuing

A method for planning a radio network by a cellular operator has been proposed. The urgency of the task is due to the desire of service providers to minimize the costs of the distribution and maintenance of the required number of base stations while ensuring the required signal / noise level within the coverage area. The problem is solved by a rational choice of the location of the repeater base points in several stages. First of all, an analysis of a site is carried out and a preliminary selection is made on it of a set of points where base stations can potentially be located. As a rule, this problem is solved using specialized geographic information systems. At the second stage, the calculation of the radio range is carried out, provided the location of the repeaters at the selected points. At the third stage, on the basis of preliminary calculations, the selection of the positions of the base stations is carried out directly. It is proposed to use a stochastic approach for a rational choice of positions. The expediency of this approach is due to the large number of random uncontrolled factors affecting the signal-to-noise ratio at the receiving point. In this case, the problem of optimal choice of position is considered as an extremal problem, in which the parameters of the conditions are random variables. The implementation of the method proposed by the authors in the paper is illustrated by the example of radio communication planning on a country-type site, which is intersected by two highways. As input parameters in the example, the length of the sections of roads crossing the coverage areas of the repeaters and the concentration of subscribers on the routes is used. The objective function and the system of restrictions are compiled in such a way as to ensure that subscribers are located within the coverage area and to minimize the areas of intersection of the coverage areas of the neighboring repeaters. The use of this technique will allow us to obtain a statistically optimal arrangement of base stations on a given piece of terrain, which is confirmed by simulation modeling.

Based on the analysis of the ITU-R primary documents and the experience gained by the authors, the influence of digital audio data compression algorithms, the type of modulation of subcarrier frequencies in the OFDM block and code rate, as well as the signal-to-noise ratio during radio reception on the quality of the transmitted audio content is considered. Recommendations on the choice of the listed parameters are given.

As the number of networked devices and applications rapidly grows, particularly the Internet of Things applications, billions of devices are connected to the network and therefore managing the generated traffic becomes a needy task. Effectively managing these devices to support reliable, secure, and high-quality applications becomes challenging. The main solution to manage network traffic is the automatic classification of application aimed at identifying the semantic type of application by analyzing its network traffic and wide range of new features. This article proposes a model for dynamic network traffic classification in software-defined networks based on the modified k-means algorithm for network resources distribution to prioritized types of traffic, which allows network applications optimization.

The article shows that the type of traffic, bandwidth and guard interval in IEEE 802.11 technologies have a minor effect on the quality of service indicators. At the same time, the difference between the multi-service traffic service capabilities between IEEE 802.11n and IEEE 802.11ac is insignificant, and the gain from changing the guard interval can reach 10 % of network bandwidth. The study was conducted on a model and a real-life network.

Current trends in software-defined radio (SDR) penetration into science, production and education is determined by the appearance on the market of affordable and multifunctional software and hardware solutions. Analysis of the experience of a number of foreign universities suggests a new educational paradigm in the field of telecommunications and radio communications related to the direction of the SDR. From an educational point of view, the field of the SDR is interdisciplinary and covers the following courses: radio receiving and radio transmitting devices, digital signal processing, theory of electrical communication, programming and simulation modeling. The integrating role of the SDR course is to develop a system approach for analyzing and synthesizing a modern transceiver with the ability to programmatically implement most of the functions of the physical layer and with final approbation of its work in real field conditions. The purpose of this work is to review current trends in the creation of a curriculum for training specialists in the course “Principles and Technologies of Digital Communication Based on Software Defined Radio”. Thus the work analyzes architecture and evolution of the SDR radio station, current trends and foreign experience in the use of SDR in education, the hardware structure of the radio receiver RTL-SDR, features of the implementation of the SDR transceiver in open source software. To assess the performance indicators of the SDR transceivers, the conclusion contains approach for half-natural experiment testing on the Keysight test bench.

A review of various approaches to improving the joint forms of representing the energy distribution of signals with a complex structure in the time-frequency space is presented. Including on the basis of the use of reassignment procedures, based on the results of secondary processing of marginal forms of joint distributions and their functions of high-order moment moments. The advantages and limitations of these approaches are shown.

The article considers the classification of attacks on information resources using "classic" machine learning algorithms: k-Nearest Neighbors, Logistic Regression, Naive Bayes, Support Vectors, also ensemble methods: Decision Tree, Random Forest and Ada Boost. The research was conducted on the NSL-KDD data set using Python programming language libraries: scikit-learn, pandas and jupyter notebook. Data in the dataset were prepared for the research along with optimization of machine learning algorithm parameters. All fields in the dataset were marked with five classes, which correspond to four categories of attacks (DoS, U2R, R2L, Probe) and normal traffic (normal). A comparative analysis of the classification of each algorithm were made using different evaluation metrics. It was concluded that all the reasearched algorithms have shown insufficient efficiency in the conditions of data imbalance. It was proposed to perform additional actions on the initial dataset for better classification. The best results were demonstrated by the Random Forest algorithm.

Development and creation of semiconductor devices updates a problem of the preliminary modeling allowing lowering substantially costs of carrying out scientific and technological research. In the presented material of work information approach on creation of fractal model of the semiconductor structure taking into account atomic designs of chemical elements providing a possibility of a priori research and calculation of standard indicators of working processes of the semiconductor is considered. The methodological basis of process of modeling of semiconductors is represented a basis for development of heterogeneous designs.