Proceedings of Telecommunication Universities

Radio communication systems in telemetry and telemechanics systems of active electrochemical protection of underground metal structures are considered. The requirements for radio exchange systems for data collection networks from remote control and measuring points of cathodic protection stations are formulated. The analysis of the applicability of known exchange protocols based on the specifications of the IEEE 802.15.4 standard and its software add-ons for such networks is carried out and the need for the development of specialized network and channel layer protocols is justified. The results of the development of specialized network protocols of the application, network and channel levels that implement data exchange modes required for the collection networks under consideration while minimizing energy consumption are presented.

At present, in most modern communication systems, for example, in modern satellite terminals, the use of scanning beam antennas, i. e. antenna arrays is assumed. At the same time, at large scanning angles, the side lobe level (SLL) increases strongly and decrease in the gain is observed. In this regard, the problem of finding a procedure for synthesizing an amplitude-phase distribution (APD) with low SLL and high gain (G) at large scanning angles comes up. One of the ways to reduce SLL and compensate for the decrease in G is to synthesize the optimal APD (in terms of the maximum G and minimum SLL) using optimization algorithms. At the same time, taking into account the characteristics of the radiation pattern of the array emitters requires numerical electrodynamic calculation. The goal of this paper is to develop a procedure for the synthesis of APD with low SLL for linear and rectangular antenna arrays at various, including large, scanning angles and compensation for G reduction using a genetic algorithm and numerical electrodynamic calculation. The methods for studying the characteristics of antenna radiators are numerical electrodynamic modeling by the finite element method (FEM) in Ansys HFSS computer-aided design system and optimization of the APD  for a given radiation pattern(RP) by a random search method using partial diagrams of antenna elements. The novelty is the combination of accurate numerical electrodynamic calculation of the RP of antenna elements and optimization search for APD for the synthesis of the required RP using partial diagrams. As a result, a procedure for APD synthesis of linear and uniform rectangular equidistant (for example, 8- and 64-element) antenna arrays has been developed, taking into account the exact electrodynamic characteristics of antenna elements and their mutual resistance. Radiation patterns were obtained taking into account the effect of neighboring elements, with the help of which, using a genetic algorithm, APDs on emitters were found at different scanning angles. The change in SLL and G of the antenna array is analyzed at different scanning angles using different APDs. The proposed algorithm allows to synthesize APD for a RP with low SLL and high G at scanning angles up to 40° for linear antenna array and up to 80° in the case of a uniform rectangular antenna array. The results of this work are relevant in the problems of radiation pattern synthesis, since the proposed solution provides a significant gain in the radiation pattern synthesis rate of APD of linear and rectangular antenna arrays, especially for systems with a large number of antenna elements. At the same time, it is possible to maintain a high G at large scanning angles, and achieve a significant reduction of SLL.

This article proposes the calculation of the probabilities of incoherent reception of signals with binary relative phase manipulation (OFM–2) in the presence of several harmonic interference. Examples of calculating the error probability per bit of receiving signals from OFM – 2 according to the presented method in the presence of several harmonic interference are shown. The obtained graphs depend on the magnitude of the signal at different values of interference and the same magnitude of the frequency shift, as well as on the frequency shift of interference at different levels of signals and interference. The results of the study using this technique allow us to calculate with high accuracy and reliable forecasting the reliability of transmitted information in radio communication channels under the influence of several harmonic interference during processing on two clock cycles. And also to predict the maximum damage to the process of transmitting information in a radio communication channel under various conditions: the coincidence of interference frequencies with the signal frequency, the offset of interference frequencies relative to the signal frequency and the spread of interference frequencies with the signal frequency.

Existing datasets for testing SLAM algorithms in outdoor environments are not suitable for assessing the influence of weather conditions on localization accuracy. Obtaining a suitable dataset from the real world is difficult due to the long data collection period and the inability to exclude dynamic environmental factors. Artificially generated datasets make it possible to bypass the described limitations, but up to date, researchers have not identified testing SLAM algorithms under different weather conditions as a stand-alone task, despite the fact that it is one of the main aspects of the difference between outdoor and indoor environments. This work presents a new open dataset that consists of 36 sequences of robot movement in an urban environment or rough terrain, in the form of images from a stereo camera and the ground truth position of the robot, collected at a frequency of 30 Hz. Movement within one area occurs along a fixed route; the sequences are distinguished only by whether conditions, which can make it possible to correctly assess the influence of weather phenomena on the accuracy of localization.