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A method of long-term combined accumulation of the reflected signal is justified, which provides for its division into disjoint subsets, coherent accumulation in subsets using one of the fast algorithms and subsequent incoherent accumulation of the squares of the modules of the results of processing the subsets. A distinctive method’s feature is the use with incoherent accumulation of maxima of the squares of the moduli of the coherent processing results, that are selected from the range / radial velocity regions in accordance with a given hypothesis about the minimum and maximum values of the target radial velocity and the radial acceleration detection channel setting.The efficiency of the method was confirmed by simulation modeling. Using the theories of ordinal statistics and the method of moments, a method for calculating the probability of correct detection is developed. Estimates of processing losses are made in comparison with coherent and incoherent accumulation algorithms for a signal reflected from a point target, for the case when there is no range and frequency migration. Estimates for the required number of receiver channels are given.

The features of the implementation of the algorithm for the synthesis of detail radar images for an aperture synthesis radar using the built-in functions of the Cuda library are presented. The estimation of computational complexity from the standpoint of the organization of parallel computing on Nvidia GPUs is given. The estimation of the real performance of radar synthesis is given, taking into account the volume and features of the placement of primary radar information.

Introduction. A radar image is an image obtained by remote sensing the earth's surface with a radar device. Radar images are characterized by background graininess caused by speckle noise, which should be filtered to improve the quality of radar images. The structure of speckle noise reduction filters often comprise one or more parameters to control the level of noise smoothing. The values of these parameters have to be selected experimentally. In works devoted to speckle noise filtering, the methods used for selecting filter paraments are rarely clarified.Aim. To present a methodology for selecting the parameters of multiplicative speckle noise filters on a radar image that are optimal in terms of the quality of the resulting image.Materials and methods. The article presents a method for determining the optimal parameters of speckle noise reduction filters. This method was applied to the most conventionally used filters. The search for optimal parameters and testing of the filters were carried out using a specially designed image, which contained the objects most frequently found on radar images. The structural similarity index (SSIM) metric was chosen as a metric that assesses the quality of filtration.Results. After determining the optimal (in terms of SSIM) parameters of speckle noise reduction filters, the filters were compared to select the best filters in terms of the quality of radar image processing. In addition, the operation of the filters under study was tested on images containing various types of objects, namely: large objects, small objects and sharp borders. Knowing which filter copes best with smoothing speckle noise in a particular area and what values of the variable parameters this requires, an optimal quality of radar images can be achieved. Filtering not only improves human perception of radar images, but also reduces the influence of speckle noise during their further processing (object detection, segmentation of areas, etc.).Conclusion. The proposed algorithm allowed optimal parameters for several speckle noise filters to be determined. The quality of filtration was assessed using an expert method (visually) by comparing images before and after filtration, differential images and one-dimensional image slices. The Frost filter and the anisotropic diffusion filter with optimal parameters showed the best processing quality according to the SSIM metric.

Introduction. Synthetic aperture radars (SAR) are important components of aviation-based systems for remote sensing of the Earth. The current level of such systems allows simultaneous radar surveys in several frequency ranges. Such surveys require complexing of the images formed in each of the frequency channels, which task is yet to be resolved.Aim. To review the formation principles and methods for joint processing of images using space and aviation-based multi-band synthetic aperture radar systems.Materials and methods. The methodology of systems analysis, involving the integral stages of decomposition, analysis and synthesis, was used. Decomposition of integrating multi-band radar images was performed considering the effect of various factors on the characteristics of radar images in different frequency ranges. Such factors include the principles of radar imaging, issues of radar images of multi-band synthetic aperture radars with real characteristics, and complexing levels.Results. According to the classical systems approach, the results of review and analysis are corresponded by appropriate conclusions on the shortcomings of each decomposition element and the synthesis of a proposal for achieving the goal. It was shown that joint processing of multi-band radar images can be carried out at the levels of signals, pixels, features and solutions, as well as their aggregates. Each approach is characterised by its shortcomings, which impede implementation of full integration of multi-band radar images without loss of information, which is due to the absence of information redundancy of radar images, compared to, e.g., optical images.Conclusion. Recommendations on the application of a particular method and the synthesis of a system for radar complexing images based on the texture-fractal approach were formulated. Directions for further work meeting all the requirements for completeness, reliability and information content of remote sensing of the Earth were outlined.

We obtained the analytical expressions for the mean square deviation of errors in estimating the angular coordinates of the target for quasi-optimal algorithms of processing the fluctuating signals in radar meters with a scanning multichannel receiving system under external interference. Analytical estimates are based on the construction and circulation of the Fisher information matrix with a joint estimation of the direction of arrival and power of the fluctuating reflected signal at the output of the isotropic receiving antenna and a parabolic approximation of the mean value of the decisive statistic in the vicinity of the target direction for the processing algorithm, which provides for an estimate of the average power of the reflected signal by the least square method. The research demonstrates the convergence of exact and approximate analytical estimates and the results of computer modeling. We present the results of studying the accuracy of determining the angular coordinates of the reflected signal for typical space-energy cases. It is shown that the estimation error of the angular coordinates of the reflected signal are unbiased, and at small intervals of the correlation of the reflected signal the probability density of estimation error of the target azimuth exhibits normal distribution. In case of large correlation intervals, the distribution significantly differs from normal and acquires a large positive kurtosis and asymmetry with their values depending on the angular differences of the interference source and the target. The obtained expressions can be used to evaluate the effectiveness of quasi-optimal radar meters in the conditions of external interference and in the complex modeling of radar facilities with such meters included.

Introduction. A hardware basis of modern Advanced Driver Assistance Systems (ADAS) consists of millimeterrange radars, characterized by a relatively short range (meters – tens of meters). At the same time, improving of traffic safety requires to increase the range at least to several hundred meters. The one way to achieve such values is to increase wavelength of a probing signal, to use the centimeter range of wavelengths, for example. The paper represents a detailed description of main steps of signal processing algorithm in the model of the ADAS low-power centimeter range radar, which provides fast-moving objects speed and range definition.Aim. Development of an algorithm for estimating the range and the speed of targets by an autocorrelation radar with a wide-band continuous linear frequency modulation (linear FM) signal in order to increase the rate of the ADAS system estimates formation.Materials and methods. The proposed algorithm is based on the methods of primary and secondary digital processing of radar signals. The model of a centimeter-range autocorrelation radar with a broadband continuous linear FM probing signal was used for practical researches. MATLAB software was used to process the received signal samples.Results. The algorithm has been developed to determine the speed and the range of fast-moving objects in conditions when their movement during the evaluation interval significantly exceeds the radar range resolution. The use of simplified Kalman filtering for inter-period secondary signal processing allowed to increase significantly the stability of the algorithm. In a full-scale experiment using the low-power radar model with continuous radiation of the centimeter range, it was shown that a stable assessment of a real car speed and range was provided at a distance of at least about one kilometer.Conclusion. The results of the field experiment make it possible to draw conclusions that the proposed algorithm is highly robust even in the absence of inter-period secondary processing. Its usage allows one to improve the stability of the algorithm without considerable additional computational costs. It is possible because near-linear dynamics of the observation object and of the radar carrier makes it sufficient to use a simplified implementation of Kalman filter in the form α-β-algorithm.

Introduction. Remote monitoring of layered underlying surfaces is an urgent task. To assess the performance of new algorithms for processing the radar signal reflected from the surfaces, full-scale tests are required. As their carrying out demands big expenses, simulation modeling is actual. There are many methods of estimating an electromagnetic field (EMF) scattered by the earth's surface. However, there are no proven methods and algorithms for engineering calculation of the reflected radio signal in the conditions of this problem.Aim. The aim is to develop and to verify a software model to simulate the reflected multilayer extended structure of the radio signal received on board the aircraft.Materials and methods. The core of the model was based on high-frequency electrodynamics' methods, which allowed rapid calculation for large areas of targets with any number of layers. Simulation was produced using the MATLAB software package. The developed simulation model represented the result in the form of the normalized radar cross-section (RCS) of the multilayer structure. Since the layered structure had rough boundaries, the model provided triangulation of the boundaries of the volume-distributed object. The resulting EMF was calculated using the superposition principle. Each partial EMF value on the facet was calculated taking into account the phase and the polarization of the locally incident EMF.Results. In the paper the comparison of simulation results with theoretical calculations for the normalized RCS of a two-layer structure (difference is less than 10 percent) was presented. Verification for the coefficient of variation of the envelope of the reflected radio signal from the depth of groundwater (critical error was 7 percent) was performed. RCS modeling of the absorbing layer with different degrees of roughness of the layer boundaries was carried out. The upper boundary roughness (for maximal height deviation 0.1 m) affected on specific EPR more than lower boundary. It manifested itself in decreasing of RCS down to 30 dB.Conclusion. The developed model is intended to reduce expenses for designing synthesis of subsurface imaging systems with comparison of scheme "model of device development – field tests – completion – etc". The model is designed to verify the new signal processing algorithms for subsurface radar.

Introduction. Modern air targets, particularly drones, are becoming less noticeable, while their manoeuvrability continues to improve. Trajectory processing algorithms have also been improved in order to provide for effective tracking of highly manoeuvring targets. The accuracy of filtering trajectory parameters is largely determined by the reliability of radar information. This has also required an enhanced role for strobe algorithms and the need to increase the effectiveness of strobe radar marks.Aim. To develop and investigate the efficiency of a trajectory strobe algorithm based on the target motion model in a high-speed coordinate system associated with the direction of the target motion and involving the formation of a strobe in the form of a truncated elliptical sector.Materials and methods. The study considered the target motion model in the body-fixed frame. This model was taken as the basis for new trajectory filtering algorithms based on Kalman filtering. Existing methods for strobing radar marks of the target were considered and a new approach based on filtering in the body-fixed frame proposed. The new algorithm assumes the formation of a strobe in the form of a truncated elliptical sector. This form corresponds to the most probable location of the marks of the tracked target. The effectiveness of the proposed solutions is confirmed by the results of mathematical modelling carried out using MATLAB.Results. The study produced analytical expressions for the motion model, recurrent filtering and strobe algorithm in the body-fixed frame. A comparative analysis of tracking effectiveness with the same volumes of the elliptical and proposed strobes was performed. It was established that the algorithm with strobe formation in the shape of a truncated elliptical sector provides for longer target tracking up to the time of the first loss of the mark for speed and highly manoeuvring targets, when compared to the elliptical strobe algorithm. In addition, the average duration of sector strobe tracking does not in practice depend on the initial speed of the target and provides greater accuracy for small measurement error values (less than 50 m) of the coordinates than in comparison with the elliptical one. Conclusion. The described results were achieved by the ability of the strobe in the body-fixed frame to adapt to the direction of motion and target manoeuvring, allowing high-quality target tracking within a larger speed range. Such strobe formation will also reduce the likelihood of skip-ping radar marks from the tracked target and will reduce the number of false marks belonging to other trajectories inside the strobe.

Using the method of synthesis of the information model at the automated workstation of the air traffic control dispatcher, a fragment of the user interface at the automated workstation of the radar control dispatcher of the Minsk district control center was synthesized, which allows to simulate the stages of the dispatcher's activity in the automated air traffic control system at the modern level of air traffic intensity. The verification of the adequacy and effectiveness of the synthesized user interface fragment was carried out directly with the participation of experts and specialists with experience in such systems. The adequacy of the synthesized user interface fragment was evaluated using a known consent criterion. The evaluation of the efficiency of the synthesized fragment of the user interface of the environment at the dispatcher's automated workstation was carried out under conditions of high air traffic intensity, which force the radar control dispatcher to control in critical mode of operation. Shows the advantage of a synthesized user interface fragment over an existing user interface in terms of time and accuracy. In general, the synthesized user interface fragment exceeds the existing one by about thirty percent. The synthesized user interface fragment noted the more stable activities of the subjects, as well as their better learning capability compared to the existing user interface. The developed experiment scheme allows to carry out research of engineering and psychological factors in human-machine systems of special purpose, including analysis of user interfaces at automated workstations of dispatching personnel in existing automated systems of air traffic control for their assessment and further improvement.

Introduction. The modern approach for ensuring marine activities of necessary quality related to the assessment of current information on the state of the ocean environment in Russia is clearly insufficient. The development of operational methods and instruments of observation, as well as the assessment of the state of the ocean and its forecast naturally determine such an approach. Therefore, the development of the concept, tools and methods of obtaining data is an urgent task of the operational Oceanography formation.Objective. The objective of the paper is to con-sider the concept of ocean surface monitoring using short-wave surface wave radar.Methods and materials. The paper presents a number of specific Oceanologic examples that require operational monitoring of the state of coastal waters of the oceans and individual regions. Also, it describes observational systems used in other countries. The paper pays special attention for the development of radar sensing of surface waters, carried out in our country occasionally. The resonant nature of the reflections gives the opportunity to obtain maps of high-precision measurements of surface currents and wave characteristics on the long-range area in real time. The paper notes difficulties of the experiments implementation and the results interpretation, shows the insistent issues for the establishment of the ocean surface operational monitoring, and gives the approaches for solvation of the existing problems. The paper formulates the main task of the world ocean parameters forecast for ensuring of the sea transport safety from natural and anthropogenic threats, as well as formulates the problems solution of effective nature management.Results. The paper shows that the optimal means of natural data acquisition is the creation of an observation network of coastal HF radars, which enables to assess surface currents and wave characteristics, as well as to solve the problem of monitoring. It is Important to develop an adequate coastal model and correlate its parameters with experimental data. The adaptive modeling and monitoring by modern technical means can overcome inadequacy of physical models to specific natural conditions can.Conclusion. By assimilation in hydrodynamic and wave models, these data become applicable in spatial mapping of hydrophysical inhomogeneities of the water layer, sound velocity, and underwater acoustic noise.

Nowadays the interest in search of ways of improving the efficiency of small radar cross-section aerial objects detection and localization rises against the background of widespread use of light and unmanned aerial vehi-cles. As a result, researchers pay attention to radar systems (RS) with continuous linear frequency modulation (linear FM) signal. The use of such signals gives the measurable opportunity to reduce radar system peak-speech power and to cut the cost and weightsize parameters of the RS. The paper observes low-power ground based radar implementation prospects for purposes of detection and estimation of motion rates of small-sized aerial objects. The proposed algorithm of radar signals processing enables to simplify the detection of such tar-gets. The paper reveals the structure and defines the steps of the algorithm. The fundamental for the algorithm under consideration is the method of the range-Doppler image composition of the scanned area using digital signal processing. The paper presents the results of the algorithm operation in the low-power RS of C-band radar, obtained by processing of quadrotor echo-signals during the real experiment. The results show successful solvation of the applied problem of detection and tracking on the small-sized aerial object with the radar cross-section equal to less than 0.5 m2 and the spectrum of secondary radiation characterized by the expressed multimodality. The results of the experiment validate the application of the algorithm and demonstrate the possibility of the algorithm implementation in design of portable RS and automated target acquisition centers for detecting and tracking of the small-sized aerial targets (both, single as multi agent) with the information display on operator control panel.

At present, multilateration systems are becoming increasingly important in air traffic control. This is due to their significant advantages in compare with secondary surveillance radar complexes. This article solves the problem of synthesizing an algorithm for object location estimation for multilateration system operating in passive mode. The synthesized algorithm is a combination of a procedure, the result of which is a rough estimate of the observed object coordinates, and an iterative algorithm specifying the resulting solution. The rough estimate is the result of solving a linear system of equations. The iterative refinement procedure is based on the linearization of the observational equations and does not require a large number of iterations. The paper provides a comparative statistical analysis of the proposed algorithm and the known Bancroft algorithm. For an objective analysis of two algorithms, the paper derives the Cramer-Rao boundary for the correlation matrix of estimates of the observed object coordinates, which makes it possible to determine the potential accuracy of the solution of the problem. It is shown that both algorithms allow obtaining estimates, the accuracy of which is close to the potentially achievable accuracy of the object location estimate. In contrast to the Bancroft algorithm, the rough estimate of the object location is unambiguous. This virtue reduces the total amount of computations during the algorithm implementation and reduces the probability of anomalous errors.