Introduction. In practical signal processing and its many applications, researchers and engineers try to find a number of harmonics and their frequencies in a time signal contaminated by noise. In this manuscript we propose a new approach to this problem.
Aim. The main goal of this work is to embed the original time series into a set of multi-dimensional information vectors and then use shift-invariance properties of the exponentials. The information vectors are cast into a new basis where the exponentials could be separated from each other.
Materials and methods. We derive a stable technique based on the singular value decomposition (SVD) of lagcovariance and cross-covariance matrices consisting of covariance coefficients computed for index translated copies of an original time series. For these matrices a generalized eigenvalue problem is solved.
Results. The original time series is mapped into the basis of the generalized eigenvectors and then separated into components. The phase portrait of each component is analyzed by a pattern recognition technique to distinguish between the phase portraits related to exponentials constituting the signal and the noise. A component related to the exponential has a regular structure, its phase portrait resembles a unitary circle/arc. Any commonly used method could be then used to evaluate the frequency associated with the exponential.
Conclusion. Efficiency of the proposed and existing methods is compared on the set of examples, including the white Gaussian and auto-regressive model noise. One of the significant benefits of the proposed approach is a way to distinguish false and true frequency estimates by the pattern recognition. Some automatization of the pattern recognition is completed by discarding noise-related components, associated with the eigenvectors that have a modulus less than a certain threshold.

Introduction. The paper considers the operation of an adaptive selection system for moving targets, represented by a one-time multi-period subtractor. The system of selection of moving targets is made in the form of two quadrature channels, in which high-frequency input radio signals are converted to video frequency. Goal. Investigation of the system of selection of moving targets in the conditions of amplitude and phase misalignment of quadrature channels.
Aim. The study of the operation of the moving targets selection system in the conditions of amplitude and phase mismatches of quadrature channels.
Materials and methods. The method of complex variable is used, in which the input and output signals of the adaptive selection system for moving targets are represented as a pair of complex-conjugate components.
Results. An expression is obtained for the frequency transfer function of an adaptive passive noise suppression system with a variable cut-off zone relative to the average frequency of the spectrum of interference signals. The influence of almost unavoidable amplitude and phase mismatches in the characteristics of quadrature channels is studied. Expressions are obtained for the dispersion of output noise signals of the considered system of moving targets with amplitude and phase misalignment of quadrature channels. Analytical relations for the coefficients of passive interference suppression are presented. The dependences of the jamming signal suppression coefficients were calculated and constructed depending on the deviation of the transmission coefficients of quadrature channels and the phase misalignment of the reference voltages for different values of the average frequency of the passive noise spectrum.
Conclusion. The essential dependence of the jamming signal suppression coefficient on their average frequency, as well as amplitude and phase misalignments of quadrature channels is shown. The proposed research method allows us to evaluate the effect of misalignment of quadrature channels on the operation of a moving target selection system using high-order cutting filters.

Introduction. At present, phase locked loops (PLLs) are widely used: from optimal signal detection and frequency synthesis to automatic control of phase distribution in phased scanned arrays. One of the simplest structures is a multi-stage (chain) PLL, which may contain a specially selected multi-connected control circuit. Such cascaded PLLs have wide application in solving a number of tasks of the theory of optimal estimates, multi-position phase telegraphy, in synchronizing of many tunable generators while preserving specified phase relations between their oscillations, etc. PLLs are actively used in radio physics both in analog and digital versions. One of the promising directions for collective PLLs development is the study of ensembles of neuromorphic networks based on PLL.
Aim. To obtain wave analogues characterizing the collective PLL not as a discrete network, but as a continuous (distributed) media.
Materials and methods. An unidirectional model (without mutual control circuits) of the cascade structure of the PLL.
Results. Wave analogues of cascade-coupled phase synchronization systems that do not contain mutual control circuits were found. A solution of equations of wave analogues was found. A proof of validity of the obtained approximate solution in comparison with the exact one was presented.
Conclusion. It was shown that by selecting a filter in a control circuit of each single-circuit circuit with different transmission coefficients, it is possible to obtain various types of continuous media or wave analogues of chain structures based on phase synchronization systems.

Introduction. Increasing requirements for improving of information systems for ensuring navigation safety in coastal areas of marine waters determine the search of new engineering and scientific solutions. The creation of a passive coherent location systems (PCL), based on existing sources of electromagnetic radiation (in particular, global navigation satellite system (GNSS) signals) as radar illumination of the monitored space is of particular interest. During development and implementation of the systems, there are a number of problems related to the search of highly efficient processing algorithms, to the optimization of structure and functioning modes when the system is a part of a complex multi-position monitoring system in coastal areas.
Aim. Rationale of the structure of bistatic PCL system with GNSS illumination signal, analysis of methods for increasing of the level of reflected signals, development of a general signal processing algorithm of the system receiver unit, formation of proposals for the creation of multi-position radar system (MP radar) for coastal areas navigation monitoring.
Materials and methods. Mathematical modeling, theory of signals, methods of digital signal processing.
Results. The structure of the bistatic PCL with GNSS illumination signal for monitoring in coastal areas of marine waters to ensure navigation safety has been developed. Methods for increasing the power level of satellite signals at the input of the receiving device have been proposed. General signal processing algorithm and the algorithm of CAF calculation in the bistatic PCL system using GPS C/A code satellite signal for sea surface coastal areas monitoring have been developed.
Conclusion. The considered bistatic PCL system with GNSS illumination may be applied as a part of MP radar for monitoring in areas of heavy vessel traffic to ensure the safety, for operational control of marine operations in the high seas, for quick analysis of the situation at sea in an emergency.

Introduction. For controlled thermal management of power electronics devices, an important task is to increase the efficiency of heat removal from active components.
Aim. To introduce a new approach to placing a linear contact-type heat source on the surface of thin samples in order to study the features of propagation of heat fluxes in oxide substrates from materials with different thermal conductivities.
Methods and materials. The paper presents the results of studies of the propagation of heat fluxes in oxide substrates with different thermal conductivity (glassceramic and aluminum oxide ceramic - polycor). To generate the heat flux, a linear heat source was used, for which an electrically conductive carbon fiber was applied.
Results. Thermograms and temperature distribution profiles were obtained at different periods of heating time on the surface of the substrate with a heating element and on its reverse side. It was shown that the placement of the linear heat source, implemented using an electrically conductive carbon filament, on the surface of the studied samples and time monitoring of thermograms from two opposite surfaces of the samples allowed to obtain data for evaluating the thermal properties of oxide substrates. The distribution of the heat flux in a homogeneous material near the generation point had the form of a cone of a heat pipe with a base on the surface with a heat source. The thermal cone for an aluminum oxide ceramic substrate had a larger angle of inclination than that in the case of glassceramic.
Conclusion. The results obtained allowed to propose a method for reduction of thermal resistance of a heatconducting substrate by creating conditions for increasing the area of heat-conducting section.

Introduction. Localization of objects position in closed space plays an important role in many areas of human activity, including medicine. Using indoor-positioning technologies as a part of telemedicine systems allows one to improve the quality of medical care and to reduce mortality of patients. Therefore, indoor-positioning technologies contribute to achieve the goals outlined in the Russian Federation government`s program "Healthcare development".
Aim. To study the applicability of modern radiofrequency technologies for localization of patients inside a hospital building.
Materials and methods. Scientific sources devoted to indoor-positioning based on radiofrequency technologies were analyzed. The methods used included:
- bibliographic retrieval;
- selection and verification of sources based on their relevance;
- analysis of sources by methods of deconstruction and comparative analysis .
Results. The result of the analysis indicated that radiofrequency positioning technologies allow one to locate objects using radio waves properties. The disadvantage of the technology is the penetration of radio signal through walls and floors. Given this, it is necessary to use complex algorithms to detect an object with accuracy to a specific room. Despite this disadvantage, radiofrequency technologies can be used for positioning in medical facilities since they are easy in deployment and service. Also, they are used in ready-made commercial solutions. ZigBee technology is an exception because it does not allow one to track moving objects in real-time.
Conclusion. Based on the study it was concluded that BLE technology is the most suitable for indoor-positioning in medical facilities. It is energy-efficient, it has sufficiently fast data transfer rate, good communication radius and a large range of ready-made communication equipment. It is also worth noting that most wireless medical sensors exchange data via the BLE interface.

Introduction. The effectiveness of the diagnosis of malignant neoplasms of the skin remains unsatisfactory due to the complex process of interpretation of clinical features. On the other hand, in the last two decades, noninvasive optical diagnostic methods have been actively developed, for example, digital dermatoscopy for visualization of surface neoplasms and Optical Coherence Tomography (OCT) for obtaining spatial scans. Recent advances in the study of non-invasive diagnostic tools makes this area very promising for research in a clinical condition.
Aim. Developing of software modules based on the mathematical framework of texture analysis for biomedical data systems designed for the diagnosis of skin malignant neoplasms.
Materials and methods. Algorithms of software modules developed for optical systems of our own design are presented. Algorithms for a dermatoscopic module are based on the Haar transform, Local Binary Patterns and color features. Algorithms for OCT are based on the texture features of Haralick, Tamura, fractal dimension, complex directional field and Markov random field. Studies were conducted on sets of 106 dermatoscopic and 1008 OCT images of various classes of pathologies, including melanoma and Basal Cell Carcinoma (BCC).
Results. The values of sensitivity and specificity for the dermatoscopic system and OCT were experimentally obtained.
Conclusion. The sensitivity of the dermatoscopic system is 90 % versus 93 % for other authors, as well as the specificity is 86 % versus 80 %. One of the factors of the increase can be considered the introduction of a personalized mode - the addition of comparative features evaluating a difference between a tumor and a normal tissue in the software analysis module. The improved accuracy of OCT is up to 97 % for the diagnosis of melanoma and up to 96 % for the diagnosis of BCC.

Introduction. The existing scientific and technical problem was shown that, on the one hand, in accordance with legislation and international obligations (for example, under the Aarhus Convention), the population can request data on the current state of the environment, and on the other, monitoring systems existing today unable to timely ensure their provision. The paper presents the results of studies on selection and justification of sensors for air pollution, pressure, temperature and humidity.
Aim. The development of hardware for environmental monitoring of atmospheric air pollution and its testing when choosing the optimal safe route for people to move.
Materials and methods. For data transmission, the GSM wireless module was selected; to determine the location - GPRS. Hardware system was based on the Arduino Nano microcomputer, to which these sensors were connected. Studies were conducted in Minsk, Republic of Belarus.
Results. The developed hardware combined air pollution, humidity, temperature sensors with GSM and GPRS modules was based on a microcomputer, which allowed it to be used both stationary and with an unmanned aerial vehicle (drone), and to carry out mobile monitoring. The data transmitted by the device were processed in order to build maps of air pollution. For this, sets of points gained by interpolation by the method of linear averaging of neighboring values were plotted on the map. Pollution values were displayed on the map by color coding.
Conclusion. The maps thus gained can be used, for example, to select an optimal route for people to move in the city from the point of view of minimizing the adverse effects of pollution on human health and in technological emergencies. At the time of development, the proposed solution has no analogs.