Modeling of radio monitoring systems on signals of short-wavelength adaptive radio communication systems

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.


Introduction
The current stage of development of communication systems and tools in different ranges is characterized by the improvement of technical means to implement them.However, despite the rapid development of ultra-shortwave (UHF) means of communication (trunking, cellular communication, satellite communications), which allow the formation of broadband high-speed data channels, the United States, Germany, China, Russia, etc. continues to shortwave radio communications.At the same time, leading communication equipment manufacturers are regularly presenting new developments in the field of shortwave radio communication for civilian and specialized users [1][2][3].There are many reasons for this: • long-distance communication without additional costs for network equipment (from tens of kilometers to thousands of kilometers) and, as a result, the cost of one kilometer of short-wave communication channel compared to other radio communication systems; • the use of flexible (adaptive) methods of installation and maintenance of radio communications based on modern digital information processing technologies, which allow to increase the quality and stability of high-frequency radio channels.

Solution method
Modern short-range communication systems are characterized by the ability to establish radio communication and automate the processes of guaranteed transmission of information, adapt to the noise situation in the short-wave range, the organization of analog and digital communication networks.This was possible due to the development of automatic installation and maintenance technology of radio communications (ACI-Automatic connection installation).In automatic mode, the automatic installation and maintenance technology of radio communication selects the type of signal modulation depending on the communication channel, noise-resistant encoding depth and parameters of the communication channel and controls the quality of the received data [4][5].
The analysis showed that the existing standards and ACI technology itself are constantly being improved.Currently, civil and special purpose communication systems and tools use second and third generation ACI modes.
However, due to the existing features of radio signal processing of flexible radio communication systems, there is a need to automate the process of detection, recognition and separation of these signals from the whole set of shortwave radio signals, which is one of the urgent tasks of the radio monitoring process.The radiomonitoring system of shortwave radio communication systems belongs to the class of large systems and its design, implementation, operation and evolution stages cannot be carried out without the use of various types of modeling at present.At all of the listed stages, the following characteristics should be considered for different levels of radio monitoring system processing: structural complexity and stochasticity of relationships between elements, uncertainty of behavior algorithms in different conditions, abundance of parameters and variables, incompleteness and uncertainty of initial data and environment the diversity and probability of the effect, and so on.The limited possibilities of experimental study of radiomonitoring systems make it appropriate to develop modeling techniques that allow to present the operating processes of radiomonitoring systems in an appropriate form and to evaluate the characteristics of the studied signals of flexible shortwave radiocommunication systems using mathematical models The main task of mathematical modeling is to evaluate the capabilities of a radio monitoring system for signals of shortwave radio communication systems adapted for the detection, recognition and subsequent processing of signals in a complex noise environment [6].
To conduct the study, the authors developed a mathematical model of a radio monitoring system for signals of adapted shortwave radio communication systems, the structure of which is shown in Figure 1.
The scheme shown in Figure 1 does not eliminate the various situations that may arise during the conduct of radiomonitoring of adaptive communication systems in the shortwave range and is a typical scheme of a radio monitoring system.Based on the results of this modeling, [7] allows you to evaluate the relationships between different objects (modules) of the system, select input parameters, study management issues, and select parameters whose values need to be adjusted.
The set of industrial radio radiation together with the influence of the propagation medium (extinction, distortion, etc.) and the effect of interference creates an electromagnetic field of radio signals Sc (t), which is the input vector of the radiomonitoring system: Sc(t)=Ered(t)+Einterference(t) (1) where Epomexi (t) is a vector describing the disruptive effects and interference (natural and artificial) of the radio wave propagation medium.
The implementation of Sc (t) (Realization) comes down to the input of the radiomonitoring system.Its first block is a signal detection module that detects and converts it from analog to digital (ATsP) Sc (t).
The structure of the module can include various technical means, depending on the detection functions: ATsP blocks, antenna feeding system (passive or active), radio receivers (single-channel or multi-channel), direction finder (pelengator) and others.
The main technical features of the signal detection module that allow comparing different construction options are: receiver sensitivity, frequency line width of simultaneous reception, direction of simultaneous reception of azimuth and altitude signals, permeability of processed signal flow, single signal and multi-signal dynamic range in alarm mode, the ability to allow (opportunity) to measure the basic parameters of the signals [8].
The main technical features of the signal detection module that allow comparing different construction options are: receiver sensitivity, frequency line width of simultaneous reception, direction of simultaneous reception of azimuth and altitude signals, permeability of processed signal flow, single signal and multi-signal dynamic range in alarm mode, the ability to allow (opportunity) to measure the basic parameters of the signals.
= ∑    =1 (2 where Uj is the vector of the signal with j.Each detected signal of the UREO vector is stored in the signal recording module and enters the demodulation and decoding module, as well as the technical analysis module that creates the REO vector in the form of ordered data sets grouped on each j -signal of the UREO vector containing the results of technical analysis of signal parameter Where is the central frequency of the signal; To -signal duration; Eo -signal amplitude; Df is the signal spectrum width; TM -signal modulation view (AM, ChM, FM); M is the number of positions of the signal modulated by phase modulation (FM-2, -4, -8); Vm is the manipulation speed for signals with FM-2, -4, -8.
Two modules are used in the model to separate the signals of a flexible radio communication system from the entire REO set of radio equipment: a pre-recognition module and a recognition module.The use of the two modules is determined by the recognition process and the need to shorten the subsequent processing time, as the probability of opening a flexible communication system that changes reception / transmission frequencies and operating modes during a communication session depends on the speed of detection, recognition and processing of these signals [9][10].
The pre-recognition module performs the function of "thinning" the REO vector to remove signals that do not belong to the adaptive communication system from further processing.The vector of et1 format is used as a reference: ET1 = {Fн, ∆F, Vм}. ( If the analyzed parameters of the REO signal with i correspond to the reference values of et1, an RPR control signal is generated from the REO set, which is given to the input of the control module in the initial recognition module and contains the Nind signal index, which must then be recognized in the recognition module. The control module is designed to control the alarm detection system and to generate the reference values et1 and et2.Its output includes the Rr control signal, which contains the command that allows the recognition procedure to be performed, and the Nind index signal in the REO common, which must be recognized, and ET2 = {TI, nм, υм, U} (5) format et2 reference vector is formed.After the recognition module captures the Rr signal and the et2 vector from the control module, it compares the remaining signal parameters with the N ind index in general with REO's et2, and if they match, includes a permission command to perform demodulation and de-coding at the module output the received RD control signal and the Nind signal together with the UREO to be processed are generated [11][12].
The demodulation and decoding module, after obtaining permission to perform, asks the module for Nind index signal entries and performs demodulation and decoding operations, and in case of successful implementation, semantic information in the form of doc, xls, txt, pdf, rtf, etc. is formed at the output of the module.

Conclusion
The design of the radiomonitoring system model of the given short-wavelength radio communication adaptive systems allows to evaluate the weight coefficients of their properties in the future, which can lead to a significant reduction in modeling time.
The purpose of further research is to decompose the process of information retrieval (decomposition) and substantiate the content of the main stages of signal processing, as well as to assess the effectiveness, adequacy and universality of the proposed model of radiomonitoring system.

Figure 1 .
Figure 1.The structure of the mathematical model of the radio monitoring system.