Radio Lines Research Articles

Looking in the axion mirror: An all-sky analysis of stimulated decay

Axion dark matter (DM) produces echo images of bright radio sources via stimulated decay. These images appear as a faint radio line centered at half the axion mass, with the line width set by the DM velocity dispersion. Due to the kinematics of the decay, the echo can be emitted in the direction nearly opposite to the incoming source of stimulating radiation, meaning that axions effectively behave as imperfect monochromatic mirrors. We present an all-sky analysis of axion DM-induced echo images using extragalactic radio point sources, Galactic supernova remnants (SNRs), and Galactic synchrotron radiation (GSR) as sources of stimulating radiation. The aggregate signal strength is not significantly affected by unknown properties of individual sources of stimulating radiation, which we sample from an empirical distribution to generate an ensemble of realizations for the all-sky signal template. We perform forecasts for CHIME, HERA, CHORD, HIRAX, and BURSTT, finding that they can run as competitive axion experiments simultaneously with other objectives, requiring no new hardware. Published by the American Physical Society 2024

A VLBA-uGMRT search for candidate binary black holes: study of six X-shaped radio galaxies with double-peaked emission lines

ABSTRACT Identifying methods to discover dual active galactic nucleus (AGN) has proven to be challenging. Several indirect tracers have been explored in the literature, including X/S-shaped radio morphologies and double-peaked (DP) emission lines in the optical spectra. However, the detection rates of confirmed dual AGN candidates from the individual methods remain extremely small. We search for binary black holes (BBH) in a sample of six sources that exhibit both X-shaped radio morphology and DP emission lines using the Very Long Baseline Array (VLBA). Three out of the six sources show dual VLBA compact components, making them strong candidates for BBH sources. In addition, we present deep uGMRT images revealing the exquisite details of the X-shaped wings in three sources. We present a detailed precession modeling analysis of these sources. The black hole separations estimated from the simplistic geodetic precession model are incompatible with those estimated from emission line offsets and the VLBA separations. However, precession induced by a non-coplanar secondary black hole is a feasible mechanism for explaining the observed X-shaped radio morphologies and the black hole separations estimated from other methods. The black hole separations estimated from the double-peaked emission lines agree well with the VLBA compact component separations. Future multifrequency VLBA observations will be critical in ruling out or confirming the BBH scenario in the three galaxies with dual component detections.

Transmission of information on a single carrier frequency in a full-duplex radio line

Telecommunication communication is usually provided in duplex mode, which requires the provision of two carrier frequencies and at least twice the bandwidth of the radio channel in a wireless version (subject to a priori equality of the capacities of information sources at both ends of the radio line). Throughout the development of wireless telecommunications technologies, the issue of the efficiency of using the frequency spectrum allocated for transmitting/receiving messages is acutely relevant, namely, reducing the bandwidth occupied by the message. This task has significant limitations, primarily based on minimizing the distortion of transmitted messages that may occur when artificially limiting the bandwidth. Information compression/compaction methods provide some savings in the width of the frequency spectrum, but a marginal reduction in the occupied frequency band can be achieved when the receiving and transmitting paths of both directions operate at the same carrier frequency. The article provides a brief overview of methods to improve the efficiency of using the frequency resource, provides a computer model and a study of the method of wireless information transmission that allows a full-duplex wireless communication channel to be implemented on a single carrier frequency. The above and investigated computer model of the method based on the use of a circulator made it possible to evaluate the effect of additive noise, the difference in amplitude and phase of the interference signal from the transmitter and a copy of the signal from the radio transmitter in "antiphase" on the number of errors (BER). According to the research results, it can be concluded that in order to reduce the number of errors when using a compensator, it is necessary to ensure an exact match of the interference signal from the transmitter and a copy of the signal from the radio transmitter in "antiphase" in amplitude and the phase difference between these signals is equal to 1800. Since an increase in the amplitude difference starting from 0.001 and the phase deviation from 0.10 from 1800 leads to a significant increase in the number of errors even with large values of the signal-to-noise ratio. In addition, when developing a device based on this method, it is necessary to take into account the difference in the amplitudes of the useful signal and "interference from the transmitter". This parameter specifies additional requirements for the device. The task of compensating for interference from the transmitter is simplified by the fact that the parameters of the transmitting signal and the characteristics of the device elements are known in advance.

Adiabatic axion-photon mixing near neutron stars

One of the promising new proposals to search for axions in astrophysical environments is to look for narrow radio lines produced from the resonant conversion of axion dark matter falling through the magnetospheres of neutron stars. For sufficiently strong magnetic fields, axion masses in the O(10 μeV) range, and axion-photon couplings gaγ≳10−12 GeV−1, the conversion can become hyperefficient, allowing axion-photon and photon-axion transitions to occur with O(1) probabilities. Despite the strong mixing between these particles, the observable radio flux emanating from the magnetosphere is expected to be heavily suppressed—this is a consequence of the fact that photons sourced by infalling axions have a high probability of converting back into axions before escaping the magnetosphere. In this work, we study the evolution of the axion and photon phase space near the surface of highly magnetized neutron stars in the adiabatic regime, quantifying for the first time the properties of the radio flux that arise at high axion-photon couplings. We show that previous attempts to mimic the scaling in this regime have been overly conservative in their treatment, and that the suppression can be largely circumvented for radio observations targeting neutron star populations. Published by the American Physical Society 2024

МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ ПРОЦЕСІВ ФУНКЦІОНУВАННЯ АВТОМАТИЗОВАНИХ СИСТЕМ ВІЙСЬКОВОГО РАДІОЗВ’ЯЗКУ В УМОВАХ ЇХ ЗАХИСТУ ВІД РАДІОРОЗВІДКИ

The article reveals the basic theoretical provisions and the essence of the approach to modeling the processes of functioning of automated military radio communication systems in terms of their protection against radio reconnaissance. An algorithm for determining rational radio exchange routes with low intelligence availability in an automated military radio communication system is proposed, which is the basis for solving the problem of multi-path routing and takes into account, in addition to the known limitations, the restrictions on the permissible intelligence availability of information flow routes, which is essential for military radio communication. A mathematical model of the functioning of an automated military radio communication system has been developed, which for the first time: takes into account the process of its protection against radio reconnaissance by radio exchange along rational routes with low intelligence availability; is based on the tensor dependencies of the coefficients of intelligence availability of individual direct radio communication lines on the quality indicators of information exchange in the elementary basis of the structure of the automated military radio communication system with their subsequent transformation to tensor dependencies of the coefficients The proposed theoretical positions can be used in the creation of training complexes (training base) based on artificial intelligence in order to increase the efficiency of troop training.

A complete solution for anti-jaming radio data-link of an unmanned aerial vehicle

The effectiveness of an unmanned aerial vehicle's flight mission over a given distance depends on many factors. However, one of the key factors in the successful completion of a flight mission is the availability of high-quality management and control of telemetry by an unmanned aerial vehicle, which in turn is determined by a reliable radio communication between the ground control station and the unmanned aerial vehicle. The current stage of use of unmanned aerial vehicles is characterised by the use of active jammers of various types and purposes, the purpose of which is to disable control channels, navigation channels, telemetry channels and data transmission channels of FPV unmanned aerial vehicles in order to prevent the successful completion of the flight mission of the vehicle. The article considers conceptual issues of implementing a guaranteed interference-free radio data transmission and control of an unmanned aerial vehicle in the conditions of active jamming interference when combining various technological solutions. These solutions include the selection and justification of a special frequency range, the use of structural circuit solutions for interference protection of the radio data transmission and control line; the use of a specific scheme for organising communication with an unmanned aerial vehicle; the use of a transceiver and portable and light antennas for the radio channel that meet reasonable technical requirements; the implementation of the possibility of real-time monitoring of the interference situation on board the unmanned aerial vehicle and detection of the type of interference; ensuring flight in the sector. The requirements were justified and options for selecting a transceiver and antenna were proposed. A structural diagram of the radio line is developed and options for its use as a data transmission and control radio line for an unmanned aerial vehicle are proposed. Examples of real-time tracking of the interference situation on board an unmanned vehicle and detection of the type of interference are given. A flight option in the sector without the use of antenna tracking is calculated and justified. The approximate values of the signal at the receiver input of the unmanned vehicle are calculated.

БАЗА ДАНИХ ДЛЯ АВТОМАТИЗОВАНОГО РОЗПІЗНАВАННЯ ТИПУ БЕЗПІЛОТНОГО АВІАЦІЙНОГО КОМПЛЕКСУ ЗА ЙОГО РАДІОСИГНАЛАМИ

The detection and technical analysis of the radio transmitters radiation of the unmanned aerial complexes elements allows to establish the fact of their use of and to identify type. Recognizing the type of unmanned aerial complex by their radio signals is carried out by comparing the estimated parameters of radio signals with known values stored in the database. The structure of the unmanned aerial complexes radio signal database based on the relational data model is proposed in the article. It is a set of interdependent two-dimensional tables that store information about parameters and characteristics of radio signals of control, telemetry and data radio lines, operating frequencies of receivers of the global navigation satellite systems, as well as purpose, belonging, aerodynamic scheme, appearance, main tactical and technical characteristics and recommendations for countermeasures. Information about the characteristics of unmanned aerial complex channels radio signals contains data on the frequency bands of the radio channel, spread spectrum parameters, modulation parameters, images of amplitude-frequency spectra and spectrograms. The use of the information collected in the database makes it possible to recognize the unmanned aerial complex type by its radio signals and to make a decision about the frequency bands in which the suppression of radio channel receivers, navigation equipment will be carried out, and to choose the most effective radio interference. Special software of the unmanned aerial complexes radio signal database was developed in accordance with the proposed structure. Special software allows you to view, edit, copy, add new information about unmanned aerial complexes, parameters and characteristics of their radio channels, as well as search. The special software user interface provides a simultaneous view of all information about unmanned aerial complex, parameters and characteristics of its radio signals. Keywords: database; radio signal; unmanned aircraft complex; parameter; characteristic; identification; countermeasure; special software.

The Environmental Impacts of Radio Frequency and Power Line Communication for Advanced Metering Infrastructures in Smart Grids.

In the neighborhood area network (NAN), the advanced metering infrastructure (AMI) enables a bidirectional connection between the smart meter (SM) and the data concentrator (DC). Sensors, such as smart meter nodes or environmental sensor nodes, play a crucial role in measuring and transmitting data to central units for advanced monitoring, management, and analysis of energy consumption. Wired and wireless communication technologies are used to implement the AMI-NAN. This paper delves into a novel approach for optimizing the choice of communication medium, air for radio frequency (RF) or power lines for power line communication (PLC), between the SM and DC in the context of the AMI-NAN. The authors methodically select the specific technologies, RF and NB-PLC (narrowband power line communication), and meticulously characterize their attributes. Then, a comparative analysis spanning rural, urban, and industrial settings is conducted to evaluate the proposed method. The overall reliability performance of the AMI-NAN system requires a packet error rate (PER) lower than 10%. To this end, an efficient approach is introduced to assess and enhance the reliability of NB-PLC and RF for AMI-NAN applications. Simulation results demonstrate that wireless communication is the optimal choice for the rural scenario, especially for a signal-to-noise ratio (SNR) lower than 25 dB. However, in urban environments characterized by higher SNR values and moderately dense networks, NB-PLC gains prominence. In denser networks, it outperforms wireless communication, exhibiting a remarkable 10 dB gain for a bit error rate (BER) of 10-3. Moreover, in industrial zones characterized by intricate network topologies and non-linear loads, the power line channel emerges as the optimal choice for data transmission.

ANTENNAS FOR INSTALLATION ON UNMANNED AERIAL VEHICLES

The widespread use of unmanned aerial vehicles for various purposes, expanding scope of their application and ever-increasing requirements for the durability of communication channels urgently require the development of new effective antenna solutions for the equipment of command radio control lines and payloads. The article is devoted to a brief analysis of the available information about the radio lines of unmanned aerial vehicles, solutions in the field of antennas for the equipment of command control radio lines and payload and the study of perspective antennas for the repeaters placed on unmanned aerial vehicles. The review of the general types of antennas that may be installed on unmanned aerial vehicles, including pin, microstrip and spiral ones, as well as antenna arrays based on them, made it possible to substantiate the prospects of using low-profile and spiral antennas for repeaters installed on unmanned aerial vehicles. The studies conducted on the frequency and spatial characteristics of low-profile and spiral antennas have confirmed their sufficient effectiveness. Proposed solutions can be used as a basis for development of perspective antennas for repeaters installed on unmanned aerial vehicles.

On the Nature of Long Period Radio Pulsar GPM J1839-10: Death Line and Pulse Width

Recently another long period radio pulsar GPM J1839−10 has been reported, similar to GLEAM-X J162759.5−523504.3. Previously, the energy budget and rotational evolution of long period radio pulsars had been considered. This time, the death line and pulse width for neutron star and white dwarf pulsars are investigated. The pulse width is included as the second criterion for neutron star and white dwarf pulsars. It is found that: (1) PSR J0250+5854 and PSR J0901−4046 etc. should be normal radio pulsars. They have narrow pulse width and they lie near the radio emission death line. (2) The two long period radio pulsars GLEAM-X J162759.5−523504.3 and GPM J1839−10 are unlikely to be normal radio pulsars. Their possible pulse width is relatively large. They lie far below the fiducial death line on the diagram. (3) GLEAM-X J162759.5−523504.3 and GPM J1839−10 may be magnetars or white dwarf radio pulsars. At present, there are many parameters and uncertainties in both of these possibilities.

Navigation Technology of Unmanned Vehicles Based on Electromagnetic Induction

The article deals with the issues of determining the position of unmanned vehicles (UV) in tunnels in the absence of signals from global navigation satellite systems (GNSS) and unfavorable operating conditions, such as low light, high humidity, radioactivity and others. The authors proposes a method for navigating unmanned vehicles based on the phenomenon of electromagnetic induction. On board the unmanned vehicle there is a high-frequency generator, a radio transmitting unit, a radio receiving unit, an information management system, and under the bearing or supporting surface of the unmanned vehicle propulsion unit there is a single-wire radio transmission line coordinated with the environment by means of an active load. The high-frequency generator transmits high-frequency current to the radio transmitting unit, which excites a single-wire radio transmission line, the single-wire radio transmission line emits a high-frequency radio signal supplied to the radio receiving unit for further conversion by the information management system into electrical control signals of an unmanned vehicle. Magnetic loops or electrical vibrators can be used as radiating antenna from the radio transmitting unit, and magnetic loops or ferrite probe excited by the high-frequency magnetic field of the radio transmission line can be used as receiving antenna. The article deals with the influence of the environment on the processes of radiation and reception of radio signals. Computer testing of the developed method was carried out with using three-dimensional electromagnetic modeling. Electrically small loop antennas located orthogonally were used to transmit and receive the radio signal. It was shown that the phase analysis of the transmission gain in both cases can provide ample information about the direction and deviation rate from the path which is set using the radio transmission line. The results of the study can be useful for the development of navigation systems for unmanned vehicles in conditions of limited availability of signals from GNSS.

THE METHOD OF IDENTIFYING THE TYPE OF UNMANNED OF THE AVIATION COMPLEX BY ITS RADIO SIGNALS

The article proposes a method for determining the type of unmanned aerial complex (UAC) based on its radio signals, which is based on a comparison of the estimated parameters of the UAV radio signals with known values stored in the database. The following characteristics and parameters of the signal are proposed as recognition features: the appearance of the amplitude-frequency spectrum (AFS) and spectrogram of the radio signal; radio line frequency range; accumulated ASF width; ASF width of the frequency element; spread spectrum parameters (hop duration; rate of frequency hopping spectrum spreading (FHSS); number of FHSS frequencies; FHSS frequency grid step); modulation parameters (symbol rate; modulation index); the position of the autocorrelation function (ACF) peaks; constant symbol sequences. Peculiarities of definition and application of the indicated recognition features are analyzed. It is shown that the most informative features are modulation parameters and constant symbol sequences. In order to increase the probability of correct recognition of UAC, in addition to the indicated features, it is suggested to use the power of received radio signals and the direction of the radio emission sources. A combination of two well-known approaches was used to make a decision about the type of UAC: the decision tree method and the minimum metric method. The application of the first made it possible to reduce the computational complexity due to the exclusion of operations for radio signals parameters evaluating that do not correspond to the decisions made at the previous stages. The minimum metric method was chosen taking into account the simplicity of its implementation and ensuring the possibility of expanding the list of known UAC radio signals without significantly changing the developed recognition method. The proposed method consists of six stages, in which recognition features corresponding to the signal spectral characteristics, spread spectrum parameters, modulation parameters, constant symbol sequences, power of the received radio signal and bearing on the UAV are determined in turn. The indicated features are compared with the known ones stored in the UAC radio signal database using the minimum metric method. In case of coincidence of the estimated and known information, a decision is made about the type of UAC, and the remaining stages are not performed. Verification of the developed method was carried out by applying it to the analysis of radio signals of known UAC, in particular, “Orlan-10”, “Supercam S350”, “Lancet”, “Eleron-3SV”.

Non-LTE radio recombination line analysis towards H ii region G34.25+0.14

ABSTRACT The electron temperature $T^{*}_\mathrm{ e}$ of H ii regions in local thermodynamic equilibrium (LTE) is usually calculated based on the ratio of radio combination lines (RRLs) and continuum emission. In this work, the LTE $T^{*}_\mathrm{ e}$ in the H ii region G34.25+0.14, which is especially luminous and regarded as a prime target to investigate the physical properties of an H ii region, is obtained by analysing both RRLs and continuum in L band, and employing the correction factor $b_n^{*}$ to correct for non-LTE conditions. The LTE $T^{*}_\mathrm{ e}$ values in L band are calculated to be $2580\, {\rm K}$ for H i/OH/Recombination line survey (THOR) observations and $3690\, {\rm K}$ for Survey of Ionized Gas in our Galaxy, using the Arecibo telescope (SIGGMA), respectively. By employing a non-LTE correction, we derive Te of 8900 $\, {\rm K}$ and the corresponding $b^{*}_n$ values are calculated to be 1 and close to 1 in X band and C band, respectively. However, $b_n^{*}$ at L band (${\sim} 1.4\, {\rm GHz}$) is calculated as 4.2 and 2.4 for THOR and SIGGMA, suggesting that non-LTE corrections are necessary and significantly affect the results. This work demonstrates that the assumption of LTE to calculate $T^{*}_\mathrm{ e}$ is not valid for the observed transitions in L band, and hence, non-LTE corrections are needed. Furthermore, Ne for G34.25+0.14 is calculated from multiple bands independently, consistent with previous work. This study provides a method which could be used for other H ii regions to investigate their degree of departure from LTE.

Evaluation of the Transmission Range of Videoinformation of Various Quality when Monitoring Emergency Situations from an Unmanned Aerial Vehicle

The purpose of research The aim of the study is to estimate the maximum transmission range of video information of various quality from an unmanned aerial vehicle to predict its capabilities when monitoring an emergency situation. Methods. Research methods are based on the concepts of the theory of radio electronics, the theory of diagnostics and prognostics of the technical condition of unmanned aerial vehicles. The methods of multicriteria analysis, parametric and structural synthesis were used. The principles of transmitting video information from unmanned aerial vehicles used to monitor emergency situations are analyzed. A critical assessment of the maximum transmission range of video information from unmanned aerial vehicles during emergency monitoring has been made. Results. Graphs of the dependence of the energy reserve in the radio communication line between the unmanned aerial vehicle and the ground control system have been obtained, allowing to estimate the maximum values of the transmission range of video information of various quality in the 2.4 and 5.8 GHz bands when monitoring emergencies. The maximum line-of-sight range between the UAV and the UAV slightly depends on the lifting height of the antenna of the mobile UAV and at the lifting height of the UAV from 100 to 500 m is from 40 to 85 km. The maximum range of HD quality video transmission with the FM-4 UAV using Turbo 7/8 turbocoding in the 2.4 and 5.8 GHz bands is 3 and 7 km, respectively, and when transmitting FHD quality video information with the CAM-16 UAV using Turbo 7/8 turbocoding in the 2.4 and 5.8 GHz bands is 1.4 and 3.3 km. Conclusion. The development of a method for determining the maximum transmission distance of video and command-telemetry information allows for a more accurate assessment of the energy reserve in the radio communication line with an unmanned aerial vehicle. Unmanned aerial vehicles for direction finding and detection of rescue beacons of victims during search and rescue operations should be considered as promising areas of research in the field of the use of unmanned aerial vehicles in emergency situations.

Features of Forecasting the Operation of Ionospheric Radio Lines in Upper Rays Modes

Features of Forecasting the Operation of Ionospheric Radio Lines in Upper Rays Modes

Features of Forecasting the Operation of Ionospheric Radio Lines in Upper Rays Modes

The frequency dependence of transmitted information qualitative indicators is analyzed on theexample of two meridional radio links: single-hop (~2600 km) and dominant two-hop (~5100 km) for basicmodes of radio wave propagation in the ionosphere. It is shown that the presence of highly efficient receivingtransmittingantennas in a radio communication system leads to the need to take the existence of a priori energeticallyextremely weak modes into account in the problem of radio path specification statement. In thiscase, we consider those formed exclusively by the mechanism of radiation transfer along the upper-angles raytrajectories in the ionospheric propagation of radio waves. If the angles of departure and arrival for suchmodes and the directions of the main lobes of the antenna patterns at the end points of the radio path coincide,the signal-to-noise ratio for the wave field can reach the required threshold value and ensure the successfuloperation of the radio communication system. This may expand the upper frequency limit for the passageof radio waves in the transition regions of jump propagation of radio waves in the ionosphere; it shouldbe taken into account in forecasting the operation of ionospheric radio links.

Development of antenna system of a new generation tropospheric communication station

Today, means of tropospheric communication play an important role in the organization of communication at distances significantly greater than the distance of direct visibility. The peculiarities of the construction of such lines, in contrast to line-of-sight radio lines, are related to the peculiarities of the propagation of ultrashort waves and their reflection from the inhomogeneities of the troposphere. At the same time, the use of tropospheric stations makes it possible to provide high-quality multi-channel communication at an interval of 150–250 km, while significantly reducing the time for deploying long-distance lines. Along with the advantages, tropospheric means of communication have rather bulky antenna devices and require a significant energy resource. In connection with this, the task of increasing energy efficiency due to the development of antenna systems of tropospheric communication stations that will meet the set requirements arises. In order to solve the problem, a parabolic antenna (a mirror with a diameter of 1.5 m) and two types of irradiators (a linear polarization irradiator and an array of 8 elementary circular polarization irradiators) were proposed as antenna systems for tropospheric communication stations. Verification of the adequacy of the proposed antennas and the possibility of their use on real means of tropospheric communication was carried out in a collimator chamber. In order to confirm the results of the inspection, field tests of the developed antenna system of the tropospheric station were conducted at an interval of 155 km. At the same time, the combined use of the proposed antenna systems for the 80 W transmitter allows for the necessary energy of the tropospheric communication line in the frequency range of 4.5-4.7 GHz.

Physical conditions and extension of the coronal line region in IC 5063

ABSTRACT We study the ionized and highly ionized gas phases in the Seyfert 2 galaxy IC 5063 by means of the Very Large Telescope (VLT)/Multi-Unit Spectroscopic Explorer (MUSE) integral field spectroscopy. Our analysis allowed us to detect a high-ionization gas outflow traced by the coronal lines [Fe vii] λ6087 and [Fe x] λ6375. Both emissions are found to be extended. The former up to 1.2 kpc and 700 pc north-west (NW) and south-east (SE) from the nucleus, respectively. The latter reaches 700 pc NW of the nucleus. This is the first time that [Fe x] emission is observed at such distances from the central engine in an active galactic nucleus. The [Fe vii] λ6087 emission peaks at the nucleus, with two secondary peaks at the position of the NW and SE radio lobes. The gas kinematics is complex, with the coronal emission displaying split line profiles along the radio jet and line widths of several hundred km s−1. Velocity shifts of up to 600 km s−1 in excess of the systemic velocity of the galaxy are found very close to the radio lobes and along the jet propagation. The extended coronal gas is characterized by temperatures reaching 20 000 K and electron densities >102 cm−3, with the larger values associated with the regions of larger turbulence, likely due to the passage of the radio jet. This hypothesis is supported by photoionization models that combine the effects of the central engine and shocks. Our work highlights the strong relationship between extended coronal emission and the radio jet, with the former suitably tracing the latter, which in the case of IC 5063, propagates very close to the galaxy disc.

Tkachenko Methodology for building radio relay lines based on the use of geospatial information

When planning and organizing communication using modern military digital radios, a crucial and relevant task is to ensure the maximum possible communication range while providing the necessary speed and quality of information transmission. The main factors determining the possible communication range of modern military digital radios, in addition to their characteristics, are the terrain relief, buildings, and vegetation. Additionally, existing height objects in the area, such as communication operator towers, can be used to organize radio relay communication. An analysis showed that existing methods and specialized software can be used for certain calculations of signal levels, but they do not always take into account all necessary technical parameters of radio equipment and additional geospatial information. Moreover, the existing software is not designed to construct multi-interval radio relay lines while considering additional geospatial data. In constructing radio relay lines, there is often a situation where one interval cannot provide communication with the required quality. This situation calls for planning a radio relay line using relay stations. The choice of the location of relay stations depends on many factors, including the possibility of establishing communication, minimizing the number of relays, geospatial information regarding the terrain relief, and the presence of the necessary infrastructure (buildings, power supply, anchor points, towers, etc.) in the area. The article proposes a methodology for constructing radio relay communication lines based on calculations of signal levels while considering geospatial data. This methodology allows analyzing individual radio relay intervals for constructing multi-interval radio relay lines. The software implementation of the developed methodology allows creating software for calculating radio relay lines with the necessary input data and geospatial information regarding the terrain.

Estimation of Probabilistic Characteristics of Reception of Frequency-Effective Signals during Propagation along a Radio Line with Fog

A model of a radio line with fog, which is used to represent distortions of complex envelopes of digital signals because of the absorbing and dispersive properties of the propagation medium, has been considered. It is shown that with an increase in the frequency band of digital signals and with an increase in their order of manipulation (when using frequency-efficient signals), the influence of these distortions leads to energy losses in relation to propagation in free space. The quantitative estimation of energy losses for the digital signals used in applications with multi-position phase, quadrature-amplitude, and amplitude-phase manipulations and for a radio line with fog with a variation of its parameters has been carried out. It has been shown that for signals with multiposition phase and amplitude-phase manipulations (the frequency efficiency coefficient of the signals is 4 bits/s/Hz), the energy losses reach 3.5 and 1.0 dB, respectively.