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• EVALUATION OF THE FUNCTIONAL ELEMENTS INFLUENCE ON THE PARAMETERS OF THE QKD SYSTEM BASED ON B92 PROTOCOL

  К.Е. Rumyantsev, P.D. Mironova, H.H. Shakir

  2022-11-01

  Abstract ▼

  The influence of the parameters of functional elements on the energy, time and probabilistic
  characteristics of the quantum key distribution system (QKD) based on the B92 protocol is studied.
  The dependences of the probability of writing correct and erroneous bits into a raw quantum
  key sequence are plotted for various lengths of a fiber-optic communication line (FOCL) and the
  use of various lasers (EML-laser; DFB-laser; VCSEL-laser and FP-laser) and photodetector
  modules (id201; id210; id220; id230). Thus, changes in the probability of writing a correct bit into
  a raw quantum key sequence are much more significant than changes in the probability of writing
  an erroneous bit (50.9 times versus 3.3 times with FWHM=80 pm and a change in the length of
  the FOCL from 10 to 100 km). This is due to the fact that with an increase in the length of the
  FOCL, the probability of the absence of registration at the receiving station of photons or dark
  current pulses (DCP) sharply increases. Numerical material indicates a direct proportional dependence
  of the probability of writing an erroneous bit on the frequency of generation of noise
  pulses of single-photon avalanche photodiodes (SAPD). So, with an increase in the frequency of
  occurrence of DCP by 60 times (from 100 to 6000 Hz), the probability of recording an erroneous
  bit also increases by 60 times (for example, with a FOCL length of 100 km – 6.39 versus 383.3).
  It has been established that the root-mean-square deviation of the photon delay time is directly proportional to the length of the FOCL and the width of the laser spectrum. With a spectrum width
  of FWHM=10 pm and an increase in the FOCL length from 10 to 100 km (by a factor of 10), the
  standard deviation of the photon delay time also increases by a factor of 10 (from 4.16 to 41.6 ps).
  To achieve the best performance of the QKD system as a whole, it is advisable to use a laser with
  a minimum width of the radiation spectrum, for example, an EML-laser. However, EML-lasers are
  considered the most complex and expensive of all the considered types of lasers, so the use of
  EML-lasers significantly increases the cost of the entire QKD system.

• ANALYSIS OF THE CAUSES OF ERRORS IN THE AMPLITUDE-PHASE DISTRIBUTION OF LINEAR PHASED ANTENNA ARRAYS AND METHODS FOR THEIR REDUCTION

  S.S. Bybin , N.P. Dunaev , S.V. Kuzmin , А.N. Morozov

  2026-02-27

  Abstract ▼

  To use a phased array antenna in the beamforming mode, it is necessary to establish a certain amplitude-phase distribution at the inputs of the emitting elements. Amplitude and phase errors distort the radiation pattern. The paper analyzes the sources of errors in the amplitude-phase distribution of phased antenna arrays, including parasitic phase shifts, nonlinear amplification paths, temperature instability and mutual electromagnetic coupling between the elements. Three methods of calibration and adjustment of phased antenna arrays are described, based on direct measurements of the transmission coefficients in the near zone and the subsequent calculation of the impact vector using inverse and pseudo-inverse matrices of mutual connections, which provides a systematic approach to error elimination. To obtain the initial values, each channel was pre-calibrated along a closed path using a vector network analyzer. Technique 1 implements correction for a set of points in space and one set of states of each channel. To increase the stability of the solution, method 2 uses the regularization of the elements of the matrix of interconnections based on an additional set of measured states of each channel. Method 3 makes it possible to construct a mathematical model of a specific implementation of a phased array antenna based on measurements with a fixed channel state, which ensures the formation of an arbitrary amplitude-phase state without repeated measurements. An experimental setup of an eight-element equidistant linear phased array antenna was carried out. The lattice attenuator/phase shifter modules are based on the PE44820 phase shifter and PE4302 attenuator debugging boards and are controlled by a microcontroller to automatically change phases and amplitudes. The measurements were carried out automatically on a near-field stand in an anechoic shielded chamber using a vector network analyzer. Calibration results are presented, matrices of mutual relationships are constructed and radiation patterns are formed, confirming the operability of the proposed approaches. Since the experimental array is low-element, the results of applying the considered techniques are compared with the results of tuning in the far zone performed using an evolutionary algorithm.

• PROBABILISTIC CHARACTERISTICS OF THE THRESHOLD ALGORITHM FOR DETECTING SYNCHRONIZING PULSES IN THE QUANTUM KEY DISTRIBUTION SYSTEM BASED ON INFORMATION FROM AN ADJACENT PAIR OF TIME SEGMENTS

  K. E. Rumyantsev, Y. K. Mironov, P.D. Mironova

  2020-11-22

  Abstract ▼

  Quantum key distribution systems (QKD) provide increased security of transmitted information.
  For the stable operation of the QKD system, accurate synchronization of user stations is
  required with minimal time costs. An algorithm for detecting a sync signal with a threshold test is
  proposed. It is assumed that the sync pulse is simultaneously in two adjacent time segments. The
  probability of detecting a pair of time segments where a sync pulse is present is determined by the
  probability of exceeding the threshold level by the total number of signal and noise pulses recorded
  in two adjacent segments. The purpose of the research is aimed at a comparative analysis of the
  threshold level and probabilistic characteristics of synchronization equipment during threshold
  testing of each pair of time segments within a time frame, obtained when orienting on the Gauss
  and Poisson model for the number of photons and dark current pulses (DCP) received during the
  time segment analysis. The probabilistic characteristics of the detection algorithm for sync signals
  are studied in a quantum key distribution system based on a comparison of the number of photons
  from an adjacent pair of time segments with a threshold level. The application of the approximation
  of the statistical properties of the processes at the output of the photodetector by the Poisson
  law and the normal distribution is analyzed. The influence of the Poisson and Gaussian models on
  the choice of the threshold level and the calculation of the synchronization efficiency during the
  threshold testing of each pair of time segments within the time frame are estimated, obtained by
  orientation on the Gauss and Poisson models for the number of photons and DCP received during
  the analysis of the time segment. It was established that the choice of the threshold level based on
  the normal distribution gives an underestimated value. The approximation of the statistics of photons
  and pulses of dark current by a normal law provides a threshold level lower than the required
  one. Moreover, the difference grows with stricter requirements for the probability of false positives.
  The obtained probabilistic properties of the sync signal detection algorithm based on the
  analysis of the sum of counts from an adjacent pair of segments with a threshold level allow us to
  formulate recommendations for choosing an approximation of the signal statistics: for express
  calculations of probabilistic characteristics, it is advisable to use the Gaussian model; if a higher
  analysis accuracy is required, it is recommended to use the Poisson model.

• NON-PARAMETRIC METHOD FOR DETECTING BREAKDOWN OF TIME SERIES USING THE RANDOM WALKS THEORY MECHANISM

  G. F. Filaretov , Z. Bouchaala

  2020-11-22

  Abstract ▼

  The task of the on-line detection of a sudden change in the probability properties of a time series
  is considered, which is usually interpreted as the detecting task of change point the characteristics
  (breakdown) in the observed stochastic process. The actuality of the development of research on this
  topic is noted, which is due to the emergence of ever new applied problems where methods and algorithms
  for breakdown detecting can be successfully used - in particular, when creating monitoring systems
  in industry, ecology, medicine, etc. Two main varieties of methods for breakdown detecting are
  discussed: parametric and nonparametric. It is noted that, although nonparametric methods, ceteris
  paribus, are inferior to parametric methods in terms of efficiency (the speed of breakdown detecting),
  they also have a number of advantages, without requiring, in particular, for their application detailed
  information about the probabilistic properties of the controlled process. This is fundamentally important
  for building monitoring systems, when detailed information about these properties may either be completely
  absent and then it is necessary to conduct a rather laborious preliminary study of it, or to be
  unreliable. An original sequential nonparametric algorithm for detecting discord is proposed based on
  the implementation of the random walk mechanism or, more specifically, using the theory of success
  runs. The operating principle of the control algorithm is explained and its description is given. The results
  of the study of the basic statistical characteristics of the algorithm, including the determination of
  its effectiveness, and results of comparison with known parametric methods, are given. The area of possible
  practical use of the proposed algorithm is highlighted, where its effectiveness remains quite high.
  The prospects of using the proposed algorithm as part of the software and algorithmic support of monitoring
  systems for various purposes are noted.

• GENERALIZED CIRCULAR CRITERION FOR THE ABSOLUTE SUSTAINABILITY OF DISTRIBUTED SYSTEMS

  Z. R. Mayransaev, A. B. Chernyshev

  2021-07-18

  Abstract ▼

  Systems control with distributed parameters is one of the complex and important sections of
  cybernetics, like the science of control, information and systems. The need to study and develop
  this scientific discipline is due to the fact that to control many objects you have to take into account
  their geometric parameters, that is, their spatial length. So far, many results have been
  achieved in the field of distributed system theory, but for the most part these results are aimed at
  the study of linear systems. In the course of researching non-linear automatic systems, as one of
  the main tasks, the task of finding possible states of equilibrium of the system under study is
  solved. Research into the sustainability of such systems is also a major challenge. Using the technique
  of decomposition of functions that describe distributed signals in rows, according to the
  general theory of the Fourier series, a class of distributed systems is allocated, in which decomposition by its own vector functions is permissible. Due to this capability, the transmission function
  that describes an object with distributed parameters appears as a combination of transmission
  functions in separate spatial mods. The concept of "generalized coordinates" is introduced to take
  into account the spatial coordinates. For systems with distributed parameters, the spatialamplifier
  gain factor is adopted as a direct non-linear angular angular ratio. A cylindrical criterion
  for the absolute stability of non-linear distributed systems has been developed and formulated,
  based on the generalization of the circular criterion. An illustration of the spatial sector of
  nonlineaivity is given. For the first time, a generalized circular criterion for the stability of distributed
  systems has been developed, taking into account the dependence of non-linear characteristics
  on spatial coordinates. A graphic illustration of this criterion is presented.

• DECIMETER RANGE GENERATOR

  A. N. Zikiy, A. S. Kochubey

  2021-07-18

  Abstract ▼

  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.

• JUSTIFICATION OF THE APPEARANCE OF A PROMISING AUTOMATED SYSTEM FOR RECORDING PERSONNEL OF THE ARMED FORCES OF THE RUSSIAN FEDERATION

  S. A. Botsvin , V.A. Khvatkov

  2021-11-14

  Abstract ▼

  Accounting of personnel of the Armed Forces of the Russian Federation (AFRF) is carried
  out using several highly specialized automated systems, which does not allow solving tasks in a
  single information space. The study identified problematic issues that arise when solving the tasks
  of accounting personnel of the AFRF, such as low efficiency, the use of various media, low reliability
  of information due to the lack of synchronization mechanisms between systems, etc.
  The main subsystems are identified and a list of elements is defined for building the functional
  structure of a promising automated system that will provide operational access to information for
  an unlimited number of officials and automatically solve the tasks of collecting, summarizing and
  presenting quantitative (statistical) data. Based on the analysis of the topological structure of the
  personnel bodies of the AFRF, it is proposed to use a hierarchical (tree-like) structure to build a
  promising automated system and transfer information between databases of different levels to
  reduce information redundancy and load on server equipment. The priority option for organizing
  data storage is distributed storage, which was chosen based on the requirements for the stability
  and reliability of the operation of a promising automated system, especially in wartime. At the
  same time, the use of replication mechanisms will allow for instant synchronization of information
  at all levels. The calculation of the required resources for storing and processing information at
  various levels, depending on the number of military personnel at each level, the frequency of occurrence
  of personnel events and the amount of memory required for storing personal information.
  On the basis of which the technical characteristics of the elements of a promising system, necessary
  and sufficient for high-quality functioning, are determined, and the requirements for the technical
  characteristics of server equipment and data storage systems are obtained. The conducted
  research made it possible to construct a scheme for the perspective appearance of an automated
  personnel accounting system and to justify the relevance of solving the problem of forming and
  developing a new automated system. In addition, the results of the work made it possible to determine
  the principles laid down in the prospective system, such as the construction of a hierarchical
  distributed database, the creation of mechanisms for synchronizing information between system
  elements, the possibility of using existing technical means and the organization of information
  interaction with other automated systems