Ways to identify bearings in two-position goniometric airborne radiomonitoring systems.

For aeronautical goniometric systems for radio monitoring of radio emission sources (RES), one of the primary tasks is the identification of bearings. It is especially difficult to solve the problem of identifying bearings if there are several RESs in the observation area in the case when they are located in the same plane with the direction finders. In this case, the problem of identifying bearings in goniometric two-position systems is solved in the process of performing a two-stage procedure. At the first stage, the primary identification of single measurements of bearings is carried out separately at each receiving position (RP) when receiving radio signals from the RES, and at the second stage, the secondary (inter-positional) identification of bearings arriving from both RPs is carried out. In the initial identification, strobe and strobeless identification algorithms are used. In the secondary identification for selection of true and false points of intersection of bearings on the plane, it is proposed to use the kinematic parameters of the relative RES. However, this type of selection does not provide interposition identification with an arbitrary nature of the movement of the RES relative to the RP, and also assumes a constant angular position of the RP base on the plane. More practical are ways of identifying bearings with RES, in which the procedure for constructing a confidence region (CR) in the form of a circle with a certain radius is used. However, a more correct form of CR is an elliptical CR, since the errors in determining the position of the RES are characterized by an error ellipse, a particular case of which is a circle. Therefore, methods for identifying coordinate information have been developed, in which elliptical CRs are used. In this case, not only the bearings of the RES, but also other measured parameters, for example, estimates of the rectangular coordinates of the RES, calculated on the basis of the triangulation method, can be used as coordinate information. The purpose of the article is to systematize and analyze the developed methods for identifying bearings, which allow one to get a fairly general idea of how to solve the problem of identifying bearings and indirect measurements of the coordinates of radio emission sources in aviation goniometric two-position radio monitoring systems. As a result, a classification of identification methods is given. The existing possibilities and limitations of using various identification methods in solving radio monitoring problems are analyzed. The necessary information on the methods and algorithms for interpositional identification of coordinate information about the position of the RES, using ellipsoidal CRs in solving the identification problem, is given. The practical significance of the presented methods is to increase the likelihood of correct identification of coordinate information, as well as the accuracy of the positioning of RES due to the use of elliptical CRs, which more accurately reflect the regularity of the distribution of errors in determining the position of RES.

Study of information completeness of radar data for air target classification.

In the article considers the estimation of completeness of radar data that obtained by the reflected signal from air spot targets as result of remote sensing. The feature space analyses based on information theory therefore evaluates maximum deviation data, which can be used for automatic target classification. The article demonstrates the study of trajectory (velocity, climb and height of flight) and signal (radar cross section and radar existing) features in respect of potential detected accuracy. As a priori data, reference information is used on various types and classes of air objects - aircraft (large transport aircraft, medium-haul aircraft, business jets, light motor aircraft, etc.). Modeling shows the most efficiency and completeness features are height of flight (Hh ≈ 5.17) and velocity (Hv ≈ 4.17) of air object systems.

Parametric profiler using a linearly frequency modulated signal.

At the Kotelnikov Institute of Radio Engineering and Electronics of RAS an experimental prototype of a parametric echo sounder-profiler with linear frequency modulation (LFM) of the sounding signal has been developed, manufactured and tested. Two chirp signals are emitted at frequencies of 144 kHz and 148 kHz. The difference reception frequencies have a frequency range of 1 kHz to 8 kHz. A wide band of differential frequencies is achieved by emitting two chirp signals. Laboratory and marine tests of the experimental model of the echo sounder-profiler have been carried out.

Stochastisation of microwave oscillations in microstrip log-periodic antenna-generator with LF noise-like modulation.

Microwave solid-state oscillators of noise-like signals are of the great interest for wireless telecommunication systems, imaging systems and electronic warfare. In the paper, the possibility of power combining in the array of three independent noise-like oscillators is investigated. The noise-like oscillators are based on the microstrip log-periodic antennas which are integrated with field-effect transistors. As an active element, NE350184С field-effect transistor with 13.5 dB gain at 12 GHz is chosen. It was previously shown that single-frequency, multifrequency or noise-like generations are possible in the active antennas. The main factors that affect the generation type are the current in the drain-source circuit of the transistor and the distance between the antenna plane and reflecting screen. It is experimentally shown, that using of the noise-like oscillator arrays makes possible the spectrum and power combining, but the construction is not enough stable and reliable.

Informative sign of determining the category of transmitted data in high-speed information transmission networks.

Difficulties arise with the recognition of the traffic category in the conditions of widespread use in telecommunication networks of many different non-standardized data transmission protocols. The article discusses the features of data transmission for the category of real-time data and data not critical to delays. As an informative feature for recognizing a data category, it is proposed to use an estimate of the bit rate of a single subscriber. The paper presents the results of an experiment to estimate the bit rate of a single subscriber of the assessment, substantiate the distribution laws of estimates, and determine the threshold value of a feature for recognizing a traffic category.

The interferometric system mathematical model development for the Doppler frequency shift determination.

This work presents the result of the received signal measuring system for processing Doppler frequency theoretical research. In the researching device means of controlling laser frequency whose amplitude is proportional to the Doppler frequency shift of the received RF signal is realized. The coherent laser beam is divided in two forming interference pattern. In this case, one of the beams passes through the delay line, which leads to a phase shift in the optical wave. The rate of this phase shift is proportional to the laser frequency, changes in which cause corresponding changes in the interference pattern. Changes in the interference pattern in center analysis makes it possible to determine the changes of the laser frequency, which depends on Doppler frequency shift of the received RF signal. In this work opposition of the requirements for the Doppler frequency shift determination interferometric system parameters (the coefficient of proportionality to conversion Doppler frequency shift of the received RF signal in laser frequency and time delay) is discovered: large dynamic measurement range and high Doppler frequency shift measurement resolution. The processing the received RF signal method is proposed. This method take into consideration these requirements. The proposed measurement algorithm implements the multiscale principle. It is pointed that the proposed processing the measurements results method can be implemented both the parallel processing in channels with different values of conversion coefficients, and sequential – with their iterative change.

Comparative results of the classification accuracy of MSTAR dataset radar images by convolutional neural networks with different architectures.

The results of MSTAR objects ten-classes classification using a VGG-type deep convolutional neural network with eight convolutional layers are presented. The maximum accuracy achieved by the network was 97.91%. In addition, the results of the MobileNetV1, Xception, InceptionV3, ResNet50, InceptionResNetV2, DenseNet121 networks, prepared using the transfer learning technique, are presented. It is shown that in the problem under consideration, the use of the listed pretrained convolutional networks did not improve the classification accuracy, which ranged from 93.79% to 97.36%. It has been established that even visually unobservable local features of the terrain background near each type of object are capable of providing a classification accuracy of about 51% (and not the expected 10% for a ten-alternative classification) even in the absence of object and their shadows. The procedure for preparing training data is described, which ensures the elimination of the influence of the terrain background on the result of neural network classification.

Magnetodielectric properties of ferrite-piezoelectric composite materials.

Ceramic composite materials based on compounds of lead zirconate-titanate and cobalt ferrite with different content of the initial components mass fraction have been synthesized. Using a complex of physicochemical methods, the microstructure and magnetodielectric properties of the synthesized ceramics have been studied. The resulting frequency dependences of the magneto-dielectric coefficient for the composite system (1-x)PZT + xCF(0.0 ≤ x ≤ 0.5) in an external magnetic field have a resonance form in the entire concentration range investigated. The largest changes in the value of the complex permittivity are observed for the sample with the composition of 0.6PZT + 0.4CF.

Estimation and analysis of the influence of ionizing radiation on the nanosatellite onboard radio electronic equipment functioning.

The paper presents the results of a calculation to study the influence of ionizing, bremsstrahlung radiation on the functioning of a nanosatellite. A comparative analysis of the results of calculating the specific ionization and radiation energy losses of protons (from 0.1 to 400 MeV) and electrons (from 0.04 to 7 MeV), as well as their path lengths in aluminum according to the formulas of various authors and the database of materials of the National Institute of Standards and Technologies is presented. Based on the analysis results, the annual dose in the aluminum structure of the SamSat-ION nanosatellite in a circular sun-synchronous orbit (SSO) is calculated. All calculations are based on the data of the energy spectra of protons and electrons of the SSO given in the "Information system Spenvis of the European Space Agency". The results of calculating the integral fluxes in aluminum under the action of protons and electrons of a circular SSO for different thicknesses are obtained, and the fraction of passed particles is shown in the approximation of a single-layer stack. Estimation of the radiation resistance of the electronic elements ISL70321SEH, ISL73321SEH and Virtex - 4QV, Virtex -5QV included in the SamSat - ION in the approximation of a double-layer stack was made for various thickness of Si and its ability to operate during the year.

The annual cycle of the error of radioaltimetric measurements of the Black Sea level due to the nonlinearity of sea waves.

The variability of the error of the altimetric determination of the Black Sea level L due to the nonlinearity of sea waves is analyzed. The nonlinearity leads to deviations in the distribution of elevations of the reflecting radio wave surface from the Gaussian distribution. The error occurs due to the fact that the median of the non-Gaussian distribution of surface elevations does not coincide with the average surface level. The analysis is carried out within the framework of the Brown model, which describes the shape of an altimetric pulse reflected from the sea surface. Data from a numerical operational model of the surface wave field are used for the analysis. When calculating the shape of the reflected pulse of the altimeter, an additional predictor is introduced – the steepness of the waves. It is shown that there is a clearly defined annual variation of the error L. Its highest values are observed in winter, when the average monthly value reaches the level of 0.25 m, in summer this error decreases to 0.08-01 m. The maximum value calculated from the three-hour characteristics of surface waves is 0.4 m, the average value is 0.17 m.