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SOLUTION OF THE INVERSE PROBLEM OF SPECTRAL GRAPH THEORY IN THE ABSENCE OF OBSERVABLE VARIABLES
А.N. Tselykh , V. S. Vasilev , L.А. Tselykh , S.А. Barkovskii163-1732025-10-01Abstract ▼The article is devoted to solving the main inverse problem of spectral graph theory – determining the main parameters of a graph based on the spectrum of its eigenvalues. The article studies cognitive causal graph models of complex systems with unknown dynamics of variables. Non-stochastic graph models with non-numeric values of nodes and links, as well as poorly defined system factors are considered. In the absence of initial data, solving the inverse problem for a directed weighted signed graph is significantly complicated. When graphs have the same topology but different weights on arcs, their spectra form a set of fuzzy collinear vectors in the solution space. The straight lines of these vectors diverge in the vector space due to their directionality to different vertices. The article proposes to use an algorithm that allows one to accurately restore the weights of a cognitive graph when the conditional principal eigenvector and the topological structure of the adjacency matrix are known. This algorithm takes into account an important feature of the adjacency matrix of the graph - the direction of the main eigenvector to the target vertex, which allows finding the correct solution from a set of fuzzy collinear vectors in the solution space. To achieve complete restoration of the graph weights with acceptable accuracy, it is proposed to combine the graph spectrum and the effective control model with the combinatorial optimization problem. Restoring the adjacency matrix weights using our approach, we compare them with the given graph. The comparison takes into account such graph parameters as the graph spectrum, similarity coefficients of the restored matrix, response and control vectors
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METHOD FOR DETECTING FEATURE POINTS OF AN IMAGE USING A SIGN REPRESENTATIONS
A. N. Karkishchenko, V. B. Mnukhin2020-11-22Abstract ▼The aim of the study is to develop a method for detecting feature points of a digital image
that is stable with respect to a certain class of brightness transformations. The need for such a
method is due to the needs of detecting feature points of images in video surveillance systems and
face recognition, often working in a changing light environment. A feature of the proposed method
that distinguishes it from a number of well-known approaches to the problem of distinguishing
characteristic points is the use of the so-called sign representation of images. In contrast to the
usual defining of a digital image by a discrete brightness function, with a sign representation, the
image is set in the form of an oriented graph corresponding to the binary relation of the increase
in brightness on a set of pixels. Thus, the sign representation determines not a single image, but a
set of images, the brightness functions of which are connected by strictly monotonic brightness
transformations. It is this property of the sign representation that determines its effectiveness for
solving the problems caused by the goal set above. A feature of the method under consideration is
a special approach to the interpretation of the characteristic points of the image. This concept in
image processing theory is not strictly defined; we can say that the characteristic point is characterized
by increased "complexity" of the image structure in its vicinity. Since the sign representation
of the image can be represented in the form of a directed graph, in this paper, to evaluate the
complexity measure of the local neighborhood of its vertices, it is proposed to use the ranking
method known in the spectral theory of graphs based on the Perron-Frobenius theorem. Its essence
lies in the fact that the value of the component of the so-called Perron eigenvector of the
adjacency matrix of this graph acts as a measure of the complexity of the vertex. To conduct experimental
studies of the proposed approach, a set of programs was developed, the results of
which confirm the efficiency of the method and demonstrate that with its help it is possible to obtain
results close to the expected ones on model examples. The paper also offers a number of recommendations
on the use of this method. -
OPTIMIZATION OF REMOTE DOPPLER RECEIVER’S PARAMETERS IN SEMI-ACTIVE RADAR SYSTEMS
P.A. Dyatlov, K.K. Bagrat2021-02-13Abstract ▼This article discusses the issues of increasing the noise immunity of semi-active radar systems
based on the use of transmitters for target illumination using harmonic radiation and remote
Doppler receivers in conjunction with a central information processing station. This solution is
not only the simplest from the point of view of hardware implementation, but also has such advantages
as high speed and increased sensitivity, as well as the ability to search-free spatial and
frequency processing of radiation. Of the shortcomings, it should be noted the low secrecy of the
functioning of this semi-active radar system. The purpose of the work is to eliminate the indicated
drawback by using frequency tuning in the illumination transmitter or when using several spaceseparated
illumination transmitters operating according to a given frequency-time scheme in a
semi-active radio-location system. In addition, the paper deals with the optimization of the main
parameters of portable Doppler receivers of semi-active radar systems. In particular, the paper
gives recommendations for reducing the blinding effect of a direct signal to a Doppler receiver
and presents a set of measures aimed at increasing the range of action of semi-active radar systems
up to forty kilometers. In this paper, we consider the case of operation of a semi-active radiolocation
system operating in a limited spatial sector using one remote receiving point. The illumination
transmitter, which is usually placed on a high-rise object, generates directional radiation,
intended primarily for solving various tasks in the field of telecommunications, for example,
providing mobile communications, relaying satellite information, etc. In this system, the illumination
transmitter is used in as a signal generator for illumination of air targets -
STUDY OF OPTICAL TRANSMISSION SPECTRA AND SURFACE TREATMENT PARAMETERS OF INTRAOCULAR LENSES
Z.A. Kokov, О. А. Molokanov, L.O. Kardanova, M.R. Kyshkhov2022-01-31Abstract ▼Manufacturers of intraocular lenses are constantly improving the parameters of artificial lenses,
functionally bringing them closer to their natural counterpart. In this work, an experimental study of a
number of important physical and technical parameters of intraocular lenses of the world's leading
manufacturers, affecting the quality of vision of operated patients, was carried out. The transmission
spectra of optical radiation of intraocular lenses in the range of 200–800 nm were investigated. In the
short-wavelength part, the measurement results showed a high efficiency of the protective properties of
intraocular lenses from ultraviolet radiation. It is shown that radiation with a wavelength of up to
350 nm is completely absorbed by the lens material, and the transmission of waves with a wavelength of
400 nm is 20 %. Further, up to a wavelength of 550 nm, an increase in the transmittance of the studied
intraocular lens to 100 % is observed, after which it gradually decreases to the end of the visible range
to 85%. The work also investigated the influence of the quality of the surface treatment of intraocular
lenses on the likelihood of secondary cataract development in the long-term period. According
to postoperative statistics, the likelihood of secondary cataract is 20–35 %. The appearance of
areas of optical opacity is due to various factors, one of which is the quality of the surface treatment
of intraocular lenses. The smoothness of the surface profile of the lens depends on the model,
manufacturing technology and material of the artificial lens. The study of the quality of surface
treatment of soft and hard intraocular lenses was carried out by atomic force microscopy. An
analysis of the results of scanning the surface of intraocular lenses and a statistical analysis of
630 clinical cases of secondary cataract in the long-term postoperative period (6 months or more)
showed their relationship. If the height of irregularities (protrusions) on the lens surface increases
to 70 nm or more, the likelihood of secondary cataract in the postoperative period increases from
6 to 15 %. -
DECIMETER RANGE GENERATOR
A. N. Zikiy, A. S. Kochubey2021-07-18Abstract ▼The receiver's heterodyne and the transmitter's master oscillator are the most important
components, as they determine their stability and range properties. In recent years, the Meteor
plant has created a number of new voltage-controlled generator chips with high electrical parameters.
However, the advertising materials of this company do not contain a number of parameters
that are important from the point of view of the consumer. Therefore, the purpose of this work
is to study the main characteristics of the generator, including those not declared by the supplier:
the width of the signal spectrum, the average steepness of the modulation characteristic, the level
of harmonics. The object of the study is the GUN382 microchip in a typical switching circuit.
The results of an experimental study of a VCO operating in the 1200 MHz region are presented.
The estimation of parasitic products in the spectrum of the output signal is given. Photos of the
spectrum of the output signal showing a small width of the spectral line are presented. The modulation
characteristics are measured when the control voltage and supply voltage change, and their
average steepness is calculated. These data allow us to make reasonable requirements for the
stability of the control and supply voltages. The results obtained can be used in receiving and
transmitting equipment for communication, navigation, and electronic warfare. The article expands
the idea of the line of generators of the Meteor plant, demonstrates their high electrical
characteristics: operating frequency range 1200 ± 16 MHz; output power of at least 1 dBm; supply
voltage + 5V; control voltage from 0 to 8 V; the level of the second and third harmonics does
not exceed minus 22 dB in relation to the useful signal. -
MASTER GENERATOR OF CENTIMETER-WAVE INTERFERENCE TRANSMITTER
A.N. Zikiy , A.S. Kochubey2021-08-11Abstract ▼The master generator of the transmitter is the most important component, since it determines
its stability and range properties. In the Russian market there are many models of auto generators
of domestic and foreign production. They differ in the element base (active element),
weight, dimensions, cost, operating frequency range, and other parameters. In many cases, the
passport and technical specifications do not contain a number of parameters that are important
for the consumer. The purpose of this work is to study the main characteristics of the generator,
including those not declared by the supplier. The object of the study is a microwave generator
module in a typical switching scheme. The results of an experimental study of a VCO operating in
the 5 GHz region are presented. The estimation of parasitic products in the spectrum of the output
signal is given. Photos of the spectrum of the output signal showing a small width of the spectral
line are presented. The modulation characteristics are measured when the control voltage and
supply voltage change, and their average steepness is calculated. These data allow us to make
reasonable requirements for the stability of the control and supply voltages. The results obtained
can be used in receiving and transmitting equipment for communication, navigation, and electronic
warfare. The article expands the idea of the line of domestic generators, demonstrates their highelectrical characteristics. The following electrical parameters have been achieved: – operating
frequency range from 4968 to 5448 MHz; – output power of at least 11 dBm; – supply voltage
minus 16 V; – control voltage from 5 to 31.5 V. -
GENERALIZED TRIGONOMETRIC SYSTEMS AND SPECTRAL TASKS WITH ADDITIONAL INTERNAL BOUNDARY CONDITIONS
A. G. Klovo , G.V. Kupovykh , А.А. Ilyukhin, I. A. Lyapunova2021-11-14Abstract ▼When solving problems related to the study of the strength properties of various structures,
some sets of trigonometric (sine or cosine), as well as hyperbolic functions are often used, which
cyclically pass into each other when taking derivatives. These sets consist of two functions, and the
last of these functions, when differentiating, passes into the first, taken respectively with a plus sign (a
trigonometric system of the first type) or a minus sign (a trigonometric system of the second type).
Trigonometric and hyperbolic functions are also used in solving many applied problems, whose
mathematical models contain second derivatives in spatial variables. If the mathematical model contains
fourth-order derivatives with respect to spatial variables, then when solving the corresponding
problems, it is possible to use functions whose fourth derivatives are proportional to these functions.
There are a number of works on the general theory of systems of functions, where generalized trigonometric
systems (GTS) of functions are described, the derivatives of a certain order of which are
proportional to these functions. In this paper, this theory is developed in the direction of studying the
quadratic forms of the functions that make up the GTS. It is shown that the quadratic forms of GTS
functions can themselves be GTS functions of the same order (of the first or second types). The obtained
identities and the created theory are used to solve spectral problems for a fourth-order operator
for functions with certain conditions. The specificity of the problems under consideration is that in
addition to the standard boundary conditions, there are additional conditions on the inner boundary.
These conditions are not sufficient to independently solve the problem in each separate domain in
which the functions under study are specified. The use of the GTS properties identified herein allows
us to solve such problems in the entire area under consideration. -
EXPERIMENTAL STUDY OF QUARTZ CALIBRATOR
А.N. Zikiy107-1132025-08-01Abstract ▼The object of research is a calibrator consisting of a quartz oscillator and a diode-based
harmonic generator with charge accumulation. The aim of the study is to identify technical parameters
and characteristics of the calibrator that are absent in the literature. An experimental
study of a quartz calibrator with a frequency grid at 50 MHz has been carried out. The following
results are presented: – overrun frequency 20 minutes after switching on; – dependence of the
frequency of the first harmonic on the supply voltage; – spectrum of harmonics in the frequency
range from 0 to 1500 MHz. A schematic diagram and a brief description of the design are given. A
photo and experimental technique are presented. The calibrator is recommended for use in receivers
and spectrum analyzers to test their performance and improve tuning accuracy. The following
electrical parameters have been achieved: – frequency setting accuracy of the first harmonic
± 2.5 kHz; – power of the first harmonic 0 dBm; – non-uniformity of harmonics in the band from
0 to 1500 MHz no more than 36 dB; – run-out of the frequency of the first harmonic in 20 minutes
34 Hz; – frequency drift of the first harmonic when the supply voltage changes from 5 to 13.5 V,
no more than 288 Hz; – the width of the spectral line at the level of minus 40 dB from the maximum
is not more than 4 Hz. Comparison of the obtained results with the known ones shows a rather
large unevenness of the harmonic power in the frequency range up to 1500 MHz. Reducing
the uneven power of harmonics can be achieved in several ways: – supplement the calibrator with
a corrector of the amplitude-frequency characteristic; – increase the frequency of the first harmonic. The advantages of this calibrator are the simplicity of the circuit and design, the possibility
of repetition in the conditions of serial production, the availability of the element base, ease of
adjustment, small weight and dimensions. Using more powerful transistors, it is possible to cover
not only the decimeter, but also the centimeter wavelength range -
GENERATOR WITH COAXIAL RESONATOR
D.Е. Gubarev, А.N. Zikiy, А. S. Kochubey89-972025-08-01Abstract ▼Autogenerators have found wide application in the receiving and transmitting equipment of
communication, navigation and radar, as they determine their stability, power and other important
parameters. The object of research in this work is a 1.5 GHz heterodyne from the C4-60 spectrum
analyzer. Since the technical description of this device does not contain a number of important
parameters, the purpose of the study is to study the frequency run-out, the frequency dependence
on the supply voltage, the harmonic level. A schematic diagram and a brief description of the generator
design are given. The simulation of a coaxial resonator in the Microwave Office package is
carried out. The amplitude-frequency characteristic of the resonator is given. The results of an
experimental study of a 1.5 GHz autogenerator are presented. The estimation of parasitic parameters
in the spectrum of the output signal is given. The frequency run-out and modulation characteristic
along the power supply circuit were measured. These data allow us to make a reasonable
requirement for the stability of the supply voltage. The results obtained can be used in the design
of receiving and transmitting communication equipment, navigation, electronic warfare. The article
may be useful for students and teachers of educational institutions in the educational design of receiving and transmitting equipment. The following electrical parameters have been achieved:
– operating frequency 1500 ±1.5 MHz; – output power of at least 13 dBm; – supply voltage minus
12.6 V; – consumption current no more than 60 mA; – frequency run-out in 24 minutes after
switching on no more than 325 kHz; – frequency departure when the voltage changes from minus
5 V to minus 13 V no more than 241 kHz. -
EXPERIMENTAL STUDY OF A PROTECTIVE DEVICE
А.V. Andrianov, D.Е. Gubarev, А.N. Zikiy, P.N. Zlaman263-2702025-07-31Abstract ▼The protective device (limiter) at the receiver input is an important component, as it ensures
the safety of the receiver operation in conditions of receiving powerful signals. The results of an
experimental study of a protective device in the 1-4 GHz band are presented. It is shown that the
minimum bandwidth losses at a low power level do not exceed 0.63 dB, the maximum bandwidth
losses are 1.23 dB. At an input power of 25 dBm, the protective device operates in a non-linear
mode, therefore it creates harmonics of the input frequency. The experimental amplitudefrequency
response (AFC) of the protective device, as well as amplitude characteristics at three
frequencies are presented. The experiment to remove the frequency response was carried out on a
vector analyzer of circuits. The experiment to remove the amplitude characteristics was carried
out using a standard signal generator and a spectrum analyzer at three frequencies: 1 GHz;
2 GHz; 4 GHz. Structurally, the protective device is a polycor substrate on which all elements
except connectors are placed. The substrate is placed in a frame-type housing and closed with two
sealed lids. Type III sockets according to GOST13317- 89 are used as connectors. A schematic
diagram and a brief description of the design are given. The following main parameters have been
achieved: losses do not exceed 1.23 dB in the operating frequency range from 1 to 4 GHz, the output signal power at a high input power level (f = 1 GHz; Rvh = 25 dBm) does not exceed
12 dBm. The protective device is recommended to be used in the input circuits of communication
receivers, navigation, radar and electronic warfare -
THEORETICAL STUDY OF ESTIMATING THE PROBABILITY OF A CONNECTION IN SYSTEMS WITH BROADBAND SIGNALS AND FHSS
D.I. Konkov , А. А. Schmidt , D.N. Polyakov , V.R. Bikbulatov285-2942025-07-24Abstract ▼The article is devoted to a theoretical study of the probabilistic characteristics of communication systems with broadband signals and pseudorandom tuning of the operating frequency in a complex electromagnetic environment. An analytical tool for calculating the communication probability is presented, taking into account the complex effects of multipath propagation, frequency-selective fading, and intentional interference. The dependence of the communication probability on the signal-to-noise ratio is investigated using integral expressions that take into account the normal power distribution at the input of the receiving device. A mathematical analysis of the transmission function of the communication channel as a complex characteristic describing the amplitude-frequency and phase distortions during signal propagation is performed. Theoretical models of synchronization processes are developed, including the stages of signal search, capture, and tracking, using the Markum function to describe the probability of signal detection against the background of Gaussian noise. Methods for optimizing the key parameters of the RFP system, such as the frequency tuning period, the total number of frequency channels, and the width of the protective frequency interval, are proposed. The theoretical foundations of adaptive control based on the maximum likelihood method and recursive filtering for estimating the parameters of the channel\are described. The energy efficiency of systems with RFP is studied, taking into account the frequency tuning losses and the necessary adjustment of the signal-to-noise ratio. A comprehensive indicator of the quality of a communication system combining probabilistic, energy, and time characteristics of the system is proposed. Analytical expressions are developed for estimating the intensity of synchronization failure based on statistical analysis of experimental data and calculation of the covariance matrix of measurement noise. The expediency of using reference signals to increase the reliability of measurements of communication channel parameters in adaptive control of the system is justified. Relations are derived for determining the duration of the synchronization window, taking into account the maximum allowable time of entering synchronism and the margin factor, which takes into account possible frequency instabilities of the reference generators. The influence of the protective frequency interval on preventing inter-channel interference and ensuring electromagnetic compatibility of neighboring channels is analyzed. The presented theoretical results provide a scientific basis for the design of radio systems with increased noise immunity and can be used in the development of adaptive algorithms for controlling RF control systems in a dynamically changing electromagnetic environment, ensuring a balance between the reliability of information transmission and the efficiency of using frequency-time resources of the communication system.
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