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The article describes the structure of a model that allows to evaluate the effectiveness of the radio monitoring system on the signals of flexible shortwave radio communication systems in adverse conditions of external interference. This model is characterized by the ability of modern short-range communication systems to establish radio communication and automate the processes of guaranteed transmission of information, adapt to the noise situation in the shortwave range, the organization of analog and digital communication networks.

The results of data processing obtained in the course of full-scale experiments on the transmission of a short-wave radio signal in the marine environment using special ball antennas are presented. The capacity of the radio communication channel in the modulation frequency band is estimated. Statistical estimates of signals and noises are obtained, which make it possible to calculate decision-making thresholds based on the theory of statistical radio engineering. It is concluded that it is possible to create a two-way voice radio communication channel between mobile underwater objects.

Cognitive communication behavior is becoming a research hotspot in the field of communication confrontation. In theory, the behavioral intention of noncooperating parties can be obtained by analyzing communication signals. Considering the complexity of the actual electromagnetic environment, even when the signal-to-noise ratio (SNR) is low, a certain accuracy still needs to be guaranteed. In this paper, according to five types of physical burst waveforms defined by the shortwave radio interoperability standard, a signal feature extraction method based on autocorrelation spectrogram features is proposed, and a two-input convolutional neural network (CNN) for classification is designed to improve the identification ability of shortwave communication behavior. The experimental results illustrate that the five kinds of shortwave radio communication behaviors can be accurately identified even when the noise is large. The research in this paper can directly analyze the communication behavior through physical layer signal without demodulation, which has the ability to grasp the communication behavior of the shortwave radio station in real time.

Extensive Air Showers (EAS), initiated by Ultra-High-Energy Cosmic Rays (UHECRs), generate geo-synchrotron and geo-magnetic radiations and they are, also, the source of excess charge processes. In the frequency range of 10 to 100 MHz, coherent radiation is formed. Many experiments use the radio detection technique for studying EAS features. The Auger Engineering Radio Array (AERA), part of the Pierre Auger Observatory, uses hundreds of radio antennas working in the frequency range of 30 to 80 MHz to support the investigation of UHECRs together with the standard surface and fluorescence detectors. The AERA radio frequency range is significantly contaminated by the human-made and usually narrow-band Radio Frequency Interference (RFI), e.g., shortwave radio transmitters. The presence of RFIs in the detected signals increases the ratio of spurious triggers; in consequence, empty data inflate the databases. This study proposes replacing the currently used IIR-notch nonadaptive filter by the delayed version of the wellknown Least Mean Squares (LMS) algorithm, which offers crucial advantage adjustment. The current study implemented 32/64-stage Delay Least Mean Squares (DLMS) filters on cost-effective Cyclone® IV and Cyclone® V as non-canonical Finite Input Response (FIR) with a sufficient safety margin for a global clock being at least 20% higher than 200 MHz, which equals the ADC sampling frequency.

A possibility of the ionosonde coverage expansion due to applying navigation satellite systems for supplying with the reliable short-wave radio communication acting along extended radio paths including multihop radio paths. It is shown on the basis of processing experimental data that the functionality increase of the vertical sounding ionosonde can be provided using the hardware-software ionospheric sounding complex that uses data of navigation satellites. The application of this complex in the place, where the vertical sounding ionosonde is located, allows to obtain the detailed picture of the electron concentration distribution not only far from the ionosonde but also inside the sounding region itself, along the trajectories that all points located under the ionosphere follow and that cross the responsibility zone of the vertical sounding station. It is shown that it is possible to create the dense network of the ionospheric control on the basis of vertical sounding stations distributed over a territory and hardware-software complexes.

High frequency (HF) communications have an important role in long distances wireless communications. This frequency band is more important than VHF and UHF, as HFfrequencies can cut longer distance with a single hopping. It has a low operation cost because it offers over-the-horizon communications without repeaters, therefore it can be used as a backup for satellite communications in emergency conditions. One of the main problems in HF communications is the prediction of the propagation direction and the frequency of optimum transmission (FOT) that must be used at a certain time. This paper introduces a new technique based on Oblique Ionosonde Station (OIS) to overcome this problem with a low cost and an easier way. This technique uses the international shortwave radio stations and the global beacons as the OIS transmitter and a normal HF receiver as the OIS receiver to verify the direction of propagation and the FOT. In addition, the critical frequency for F2 layer (fof2) was estimated in this paper for Iraq experimentally. The proposed technique was tested practically, and FOT range between Baghdad and other remote stations was estimated successfully using a radio receiver from Kenwood model R 1000 with a long wire antenna as a passive OIS system receiver.

The problem of remote diagnostics of a \"rough\" earth surface and dielectric subsurface structures in the shortwave radio wave band is considered. A new incoherent method for estimating the signal-to-noise parameter is proposed. The idea of the method for determining this parameter is that, by having synchronous information about a wave reflected from the ionosphere and about a wave reflected from the earth and the ionosphere (or having passed the ionosphere twice when probing from a satellite), it is possible to extract information about the scattering parameter. The paper presents the results of recording the quadrature components of the signal by means of the ground measuring complex of installation of coherent sounding in the short-wave range of radio waves at the test site of the Moscow State University (Moscow). A comparative analysis is performed and it is shown that according to the analytical (relative) accuracy of the definition of this parameter the new method is an order of magnitude larger than the widely used standard method. Analysis of the analytical errors in the estimation of this parameter allowed us to recommend a new method instead of the standard one. The software for synchronous registration of quadrature components of radio signals of various multiplicities in real time with the formation of a database of experimental data was developed, successfully tested and patented; one of the functions of the software is to protect the computer system from the powerful radiating pulse of the radio transmitter.

The passive interference of transmission lines to nearby radio stations may affect the effective reception and transmission of radio station signals. Therefore, the accurate calculation of the electromagnetic scattering of transmission lines under the condition of external electromagnetic waves is the basis for determining the reasonable avoidance spacing of the two. For passive stations operating in short-wave frequencies, passive interference is mainly generated by the tower, and span is one of the most significant factors affecting passive interference. This paper uses the method of moments to carry out the passive interference calculations under normal circumstances, expounds the method of calculating the electromagnetic field of transmission line at the same time. And elaborates the method for calculating the electromagnetic field of the transmission line, obtains the space electric field intensity of the transmission line at the same working frequency and space location of the plane wave. Applying the approximate formula to calculate the formula for the span and critical distance between the observation point and the transmission line.

The passive interference of transmission lines to nearby radio stations may affect the effective reception and transmission of radio station signals. Therefore, the accurate calculation of the electromagnetic scattering of transmission lines under the condition of external electromagnetic waves is the basis for determining the reasonable avoidance spacing of the two. For passive stations operating in short-wave frequencies, passive interference is mainly generated by the tower. This paper uses the method of moments to perform passive interference calculations under normal circumstances, And elaborates the method for calculating the electromagnetic field of the transmission line, obtains the space electric field intensity of the transmission line at the same working frequency and space location of the plane wave. Uses the approximate formula to inductive the formula for calculating height of tower and the protective distance.

Recently the significant increase in intensity of researches in the field of the fissile impact on geophysical processes in various environments is noted. Special attention is paid to a research of impact on an ionosphere of a potent short-wave radio emission of heating stands. Today experiments on change of an ionosphere are made generally at stands HAARP, EISCAT in Tromse (Norway). Within the Russian campaign (Tomsk) EISCAT/heating (AARI_HFOX) made from October 19 to October 30, 2016 experiments on impact on an ionosphere F-layer by the radiation potent HF. For assessment of impact of these experiments on geophysical processes mathematical methods carried out the analysis of change of the parameters of the Schumann resonances received on the basis of data from the station of constant observation of the Schumann resonances in the city of Tomsk, the Tomsk State University (Russia).