http://doi.radap.kpi.ua/issue/feed 2020-12-28T04:00:36+02:00 Oleg Sharpan radap@rtf.kpi.ua Open Journal Systems RADAP is a refereed non-profit both paper and electronic journal operated by the following people (all from the Radioengineering Faculty of Igor Sikorskiy Kyiv Politechnic Institute). http://doi.radap.kpi.ua/article/view/221497 2020-12-28T03:59:06+02:00 V. F. Yerokhin stddssss@gmail.com M. S. Irkha max_irha@ukr.net

In telecommunication radio systems with random multiple-access (RMA), user signals are characterized by a random intermittent radiation mode and the occurrence of their collisions in the propagation medium, i.e. conflicts at the physical level. Practical interest belongs to the situations when the useful and interfering (intermittent) signals are asynchronous at clock points. It should also be noted that when there are intermittent mutually non-orthogonal signals along the length of the information error more than two, the detection-separation algorithms that are optimal in terms of the minimum probability of error in estimating the discrete parameter of the useful signal are too complex. Therefore, the simplest case is investigated here, when the interfering signal is the only one. An algorithm for demodulation of a binary phase-manipulated signal is observed, which is observed at the background of a similar asynchronous clock noise, which is characterized by a random intermittent radiation mode. The minimum probability of error in the discrete information parameter estimation of the useful signal is chosen as the criterion of optimum for the synthesis. It is also assumed that all non-information parameters of the useful signal and similar interference are precisely known. The distribution medium is considered to be stationary in time. These initial data for the synthesis allow obtaining in the analysis the potential limits of the noise immunity of the digital signal demodulation, which is observed at the background of a similar intermittent noise. The result is a «framework» of the demodulation-separation procedure, which should be subsequently supplemented with nodes (blocks) of continuous parameters estimation that are not informational - frequencies, initial phases, amplitudes, shapes of bending, clock points, etc. The algorithm for demodulating a digital signal under the influence of such an asynchronous intermittent interference turns out to be about twice as complicated in comparison with the previously known one, when the signal and the interference at the clock points were assumed to be synchronous. A characteristic feature of the obtained compensation algorithm is the absence of feedback - the compensation procedure is performed forward, at the outputs of the signal correlators and interference. The result is generalized to the case when the clock frequencies of the signal and interference differ by an arbitrary value. A simplified approximation of the obtained algorithm is proposed.

2020-09-30T00:00:00+03:00 Copyright (c) 2020 V. F. Yerokhin, M. S. Irkha http://doi.radap.kpi.ua/article/view/221498 2020-12-28T03:59:18+02:00 S. O. Kozeruk skzrk@i.ua O. V. Korzhyk ov.korjik@aae.kpi.ua D. I. Volovik volovyk@radap.kpi.ua G. S. Pukha pukha@radap.kpi.ua

Introduction. The studied problem is relevant due to the growing use of unmanned small aircraft for mobile services of the mail and goods delivery, surveillance and security. At the same time, the danger of their use in events/campaigns, which pose a threat to both public and private interests, is increasing. Principally different devices are applied for surveillance; each type has its advantages and disadvantages. Passive acoustic surveillance tools provide stealth observation, but have a small detection range. It is possible to increase detection distance by improving the receiving microphones module design and developingeffective monitoring and localization algorithms. Theoretical Results. The paper presents the design of an acoustic module in the form of a tetrahedron with microphones located on its vertices. It is proposed to scan the space by angular coordinates using algorithms to generate a controlled power characteristic or controlled correlation characteristic. The theoretical justification of scanning algorithms, the results of the calculation of directivity characteristics and estimates of the error in determining the angular coordinates for each method are provided. Laboratory studies were conducted on direction finding of a noise source by the acoustic module prototype. Despite of reverberation in the room, it was possible to verify the theoretical results and confirm the advantage of the algorithm for the correlation formation of directivity. Conclusions. The results of the work can be used to create acoustic direction finders and systems for localizing noise objects. The proposed algorithm of controlled correlation characteristic can be used in monitoring tools to assess the acoustic characteristics of premises, for example, to experimentally determine the location and estimate sound absorption of enclosing constructions/the obstacles, to localize breaches in sound isolation.

2020-09-30T00:00:00+03:00 Copyright (c) 2020 S. O. Kozeruk, O. V. Korzhyk, D. I. Volovik, G. S. Pukha http://doi.radap.kpi.ua/article/view/221499 2020-12-28T03:59:29+02:00 T. A. Khodniev t.khodniev@kpi.ua M. S. Holub m.holub@xinity.dev O. V. Kuzhylnyi o.kuzhyl@xinity.dev O. М. Lysenko o.m.lysenko@kpi.ua A. Y. Varfolomieiev a.varfolomieiev@kpi.ua

In present study the challenges of reducing transmission latencies of a real-time video stream acquired from cameras connected via the MIPI CSI interface were addressed. In the study, the main components of the video stream acquisition/transmission latency are given, the degree of their contribution to the total latency was analyzed, the assessment on the potential ability to influence them when developing a real-time video stream acquisition/transmission systems was given. The issues connected with using the frame buffering in such systems are designated, primarily the impact on the total latency value when having a framebuffer in such a system. The limitations of the existing MIPI module implementations of some ARM microprocessors resulting in latency increase for MIPI CSI camera video stream acquisition were characterized. The structural and functional organization based on the use of digital streaming buses, fragmentation of video frames and DMA transactions for MIPI CSI video stream acquisition systems was proposed, which does not require the use of framebuffers and, as a result, provides the possibility of reducing the overall video stream acquisition latency. The proposed structural and functional organization could be implemented based on SoC-FPGA solutions, including the use of the existing IP-cores. Pragmatic peculiar features were described and the corresponding expression for estimating the limiting value of the latency for the proposed structural and functional organization was given. For experimental verification, a prototype of the video stream acquisition/transmission system, based on the Zynq-7000 SoC-FPGA family of Xilinx following the proposed structural and functional organization was created. Its specifics and corresponding features of its implementation were discussed in the paper. The performance of the obtained prototype was estimated, and the possible directions towards further reduction of the overall latency of video stream acquisition/transmission were considered. The results of the study may prove useful to reduce the latencies of the video streams acquired from MIPI CSI cameras in real-time video stream transmission systems based on SoC-FPGA.

2020-09-30T00:00:00+03:00 Copyright (c) 2020 T. A. Khodniev, M. S. Holub, O. V. Kuzhylnyi, O. М. Lysenko, A. Y. Varfolomieiev http://doi.radap.kpi.ua/article/view/221502 2020-12-28T04:00:08+02:00 E. A. Nelin ye.nelin@gmail.com Ya. L. Zinher singer.yana@gmail.com V. I. Popsui popsui@kivra.kpi.ua Yu. V. Nepochatykh nepochatikh@kivra.kpi.ua

Introduction. Lowpass filters (LPFs) are used to suppress unwanted harmonics and spurious signals. Microstrip LPFs are widely used in various electronic systems. New, more stringent system requirements demand increased LPF selectivity. In the previous work, we considered the calculation of the fifth-order microstrip LPF with three-dimensional (3D) stubs. According to the results of 3D modeling, the LPF frequency response (FR) has a steepness close (but slightly worse) to the steepness of the FR LPF based on lumped elements. In the presented paper the optimization of the LPF with 3D stubs is performed, the experiment results for 3D stub and LPF are given. Optimized LPF has a steeper FR than LPF based on lumped elements. 1 Features of the fifth-order LPF with 3D stubs. The quasi-lumped inductance is made by a through hole in the dielectric with an overhead conductor above it, and the quasi-lumped capacitance is made by a blind metallized hole on the signal conductor side. In addition to the use of 3D reactive elements, the LPF has the following differences from traditional solutions: 1) the stub is connected to the line by a small contact pad; 2) the stubs are placed on different sides relative to the direction of wave propagation. 2 Optimization of the LPF. Value of the stub’s rejection frequency is affected by the stub-line T-junction parasitic inductance connected in series with the stub. Parasitic inductance value depends on the depth of the stub hole and the contact pad sizes. If the LPF stubs contact pads are different in sizes, their rejection frequencies will be different. This will widen the LPF suppression band. Thus, by choosing stub holes depth and contact pads sizes, you can optimize steepness and suppression band width the LPF FR. As a result of optimization, the LPF FR steepness increased from 20.0 to 22.9 dB/GHz and the suppression band widen from 1.9 to 3.8 GHz at the level of –60 dB. The optimized FR has a steepness higher than the FR LPF based on lumped elements equal to 21.5 dB/GHz. 3 Experimental results. Photos and experimental FRs of the 3D stub and LPF with 3D stubs are given. 3D stub experimental and calculated values of the rejection frequency, the rejection level and the relative error of the calculated values are 6.41 and 5.72 GHz, −51.5 and −49.4 dB, 11% and 4%, respectively. The experimental LPF FR is in a good agreement with calculated one. 4 Results discussion. The presence of the third size in the microstrip elements provides not only a significant increase in their efficiency, but also additional design possibilities. Since the value of the parasitic inductance, which determines the rejection frequency, depends on the 3D stub hole depth, this parameter, as well as the contact pads sizes are optimization parameters to the FR steepness and suppression bandwidth. Conclusion. The use of 3D stubs as quasi-lumped capacitances allows to optimize the LPF FR by choosing the stubs hole depth and the stub contact pad sizes. As a result of LPF optimization, the FR steepness increased and the suppression band widen. The steepness of the optimized FR is higher than the FR LPF based on lumped elements.

2020-09-30T00:00:00+03:00 Copyright (c) 2020 E. A. Nelin, Ya. L. Zinher, V. I. Popsui, Yu. V. Nepochatykh http://doi.radap.kpi.ua/article/view/221500 2020-12-28T03:59:41+02:00 S. V. Zabolotnii s.zabolotnii@chdtu.edu.ua A. V. Chepynoha a.chepynoha@chdtu.edu.ua A. M. Chorniy a.chornii@chdtu.edu.ua A. V. Honcharov a.honcharov@chdtu.edu.ua

The work is devoted to the estimate accuracy comparative analysis of the experimental data parameters with exponential power distribution (EPD) using the classical Maximum Likelihood Estimation (MLE) and the original Polynomial Maximization Method (PMM). In contrast to the parametric approach of MLE, which uses the description in the form of probability density distribution, PMM is based on a partial description in the of higher-order statistics form and the mathematical apparatus of Kunchenko's stochastic polynomials. An algorithm for finding PMM estimates using 3rd order stochastic polynomials is presented. Analytical expressions allowing to determine the variance of PMM-estimates of the asymptotic case parameters and EPD parameters with a priori information are obtained. It is shown that the relative theoretical estimates accuracy of different methods significantly depends on the EPD shape parameter and matches only for a separate case of Gaussian distribution. The effectiveness of different approaches (including valuation of mean values estimates) both with and without a priori information on EPD properties was investigated by repeated statistical tests (through Monte Carlo Method). The greatest efficiency areas for each of methods depending on EPD shape parameter and sample data volume are constructed.

2020-09-30T00:00:00+03:00 Copyright (c) 2020 S. V. Zabolotnii, A. V. Chepynoha, A. M. Chorniy, A. V. Honcharov http://doi.radap.kpi.ua/article/view/221496 2020-12-28T03:58:54+02:00 L. M. Artiushyn artleonid2017@gmail.com Yu. О. Kolos yakolos@ukr.net N. M. Karashchuk knm7@ukr.net R. О. Avsiievych zeman-zeman@ukr.net D. V. Koval smartradio.koval@gmail.com

An improved methodology for calculating an antenna in the form of the open end of a rectangular waveguide with partial dielectric filling (PDF) and an excitation pin is introduced.An improvement in the antenna calculation method is provided by simultaneously taking into account the effective dielectric constant of a partial dielectric filling, changing the dimensions of the excitation pin and its displacement relative to the waveguide axis to reduce the geometric dimensions of the waveguide cross section and antenna matching in a certain frequency band enhancement. With this purpose, the value of the effective dielectric constant can be found through the intrinsic transverse vector functions of the hollow waveguide. In particular, the method provides an improved equation (9) to calculate the normalized conductivity of a coaxial waveguide transition from the side of a rectangular waveguide, which allows matching the excitation pin with the coaxial power line by determining (optimizing) its size and position in the waveguide. The obtained formula is used for normalized shunt conduction introduced by a resistance-loaded pin z1 and z2 , which may be applied in various certain cases when changing the nature of the load resistances z1 and z2 when calculating and designing other antennas and elements of microwave technology. The graphs of the dependences of the voltage standing wave ratio (VSWR) on the frequency for different radius, length of the excitation pin and its displacement relative to the axis of the rectangular waveguide are presented. With the optimal size and position of the excitation pin, the antenna matching in a certain frequency band is improved (the VSWR is reduced to a level not exceeding 1.18 in the 6-8 GHz frequency band).Also, the use of PDF allows to reduce the geometric dimensions of the cross section of the waveguide (up to 61% or more) without changing the electric size (for the 6–8 GHz frequency band the cross-sectional size of a rectangular waveguide for a wave H10 is 23 × 10 mm at a relative dielectric constant of plates thick cx = 6 mm, which equals to εr = 1,9). The charts of normalized antenna patterns in the E and H planes are presented. The reliability and validity of the results obtained is ensured by the convergence of the calculation results under boundary conditions with known results and the convergence of the formulas obtained in units of measurement.

2020-09-30T00:00:00+03:00 Copyright (c) 2020 L. M. Artiushyn, Yu. О. Kolos, N. M. Karashchuk, R. О. Avsiievych, D. V. Koval http://doi.radap.kpi.ua/article/view/221503 2020-12-28T04:00:22+02:00 O. F. Dubyna Fedorovich_daf@ukr.net O. V. Andreev Andreev@radap.kpi.ua T. N. Nikitchuk tnikitchuk@ukr.net O. M. Svintsytska Svintsytska@radap.kpi.ua

Introduction. Currently, information on the spatial description of objects is used in many areas of human activity. One of these types of information are the coordinates of the objects. These data are used in cartography, the construction of digital maps and 3D models, for the operation of the navigation means, etc. There are many software for design and analysis of digital elevation models. These are modules and packages like Spatial Analyst, 3D Analyst, ArcGIS packages, program MapInfo (MapInfo Corp.), Autodesk Map 3D of AutoCAD (Autodesk Inc.) and others. Common to them is build automation of soprovich terrain models, including the combination of the images of the stereopair, what is necessary to measure heights of objects for automated creation of digital elevation models of the earth's surface one of the key quality indicators is the accuracy of determining the heights of objects. The main influence on this indicator provides measurement error of parallax when processing stereosystem. Obtaining analytical expressions for the accuracy of the determination of the height of the object. To obtain the formula of calculating accuracy of measuring the height of objects used decomposition of the function into a Taylor series. Currently, the standard deviation of measurement errors of height of flight of the aircraft, the basis of stereozone and focal length, usually known with enough high accuracy. The main influence on the accuracy of determining the heights of objects during automatic processing of images is the accuracy of parallax. When measuring parallax, the problem is reduced to the search and discovery of images of the object in the second picture on the image of the object on the first image and measuring its position over images of other objects and noise. Using the formula of Kramer-Rao for the potential measurement accuracy of the image coordinates of the object in the picture, the Fourier transform and the parseval equality proof the identity, the formula obtained accuracy potential of combining stereochemical (measurement of parallax). We used the extreme-correlation combination method, as it can be applied for virtually any signals and systems of measurement. Analysis of the obtained results. The analysis of the obtained formulas shows that the overlay accuracy of the images deteriorates with the increase of the power spectral density of the noise on the first and second images and reducing the similarity of one image with another and also with the decrease in the effective width of a mutual spectrum spatial stereo. Increasing the value of the basis stereozone error of measurement of heights of objects first improves and then deteriorates. This deterioration is caused by the fact that the images of a stereo pair are obtained from different spatial points and images arise of perspective distortion and the distortion due to relief. Accordingly, as the base of removal increases, these distortions will increase. Conclusions. The advantage of this approach is the use of finite analytical expression. It provides the ability to calculate the potential accuracy of defining object heights when building a DMR with modern applications. The disadvantages include the complexity of calculating the moments of mutual spatial spectrum of stereo images. This approach can be applied when planning the shooting mode and the Earth surface imaging equipment for mapping, 3D models, etc.

2020-09-30T00:00:00+03:00 Copyright (c) 2020 O. F. Dubyna, O. V. Andreev, T. N. Nikitchuk, O. M. Svintsytska http://doi.radap.kpi.ua/article/view/221504 2020-12-28T04:00:36+02:00 O. Ya. Kaliuzhnyi oleksa.yakov@gmail.com

Problem statement. With the development of radio communication technologies, especially mobile, the choice of radio channel models is playing an increasingly important role. In this paper, one of the currently popular models is considered, namely, a Two-Wave radio propagation with Diffuse Power scattering, which is abbreviated in the literature as TWDP. For this model, both exact and approximate expressions for the Probability Density Function (PDF) and the Cumulative Distribution Function (CDF) of the signal envelope are known. However, their common disadvantage is the high complexity in terms of practical application. In this regard, this paper considers the possibility of a much simpler approximation of the PDF and CDF of a signal envelope based on the Nakagami’s distribution. Method development. The approximation of distributions by the Nakagami method comes down to the calculation of the second and fourth moments of a signal envelope at a channel output. Such calculations are performed in the paper, which allows to represent the specified moments as functions of two parameters of the TWDP channel: the K-factor and Δ-parameter depending from the ratio of beams amplitudes.Analysis of the approximation errors. Errors were estimated by comparing the calculations for the PDF and CDF as per exact formulas and calculations using the Nakagami approximation. In parallel, calculations were also carried out as per the approximation formulas known in the literature. The analysis showed that the Nakagami method gives errors in the calculation of the CDF that are acceptable for practical needs in all ranges of parameters values K and Δ. At the same time, the accuracy of the PDF approximation in comparison with other known methods was not very satisfactory.Conclusions. Studies carried out in this paper have confirmed the possibility of approximating the CDF of the signal envelope in the TWDP channel by the Nakagami distribution. However, the results of such approximation for the PDF were less satisfactory. The usefulness of the obtained results for the interpretation of the data of field experiments is also noted.

2020-09-30T00:00:00+03:00 Copyright (c) 2020 O. Ya. Kaliuzhnyi http://doi.radap.kpi.ua/article/view/221501 2020-12-28T03:59:56+02:00 O. F. Luhovskyi atoll-sonic@ukr.net A. I. Zilinskyi zilinski.andrew@gmail.com A. V. Shulha a.liashok@kpi.ua I. A. Gryshko griwko@ukr.net A. D. Lavrinenkov alavrinenkov@hotmail.com O. S. Haletskyi haletskijos@gmail.com O. P. Zavalii oleksandrzavaliy15@gmail.com

Introduction. The creation of modern ultrasonic cavitation equipment for filtering working fluids in various technological processes is associated with the study of the interaction of a liquid load with ultrasonic emitters, taking into account the influence of the geometric shape of the cavitation chamber. The efficiency of the operation of ultrasonic cavitation devices for filtration is a rather urgent issue today and directly depends on the quality of this agreement. Problem statement. To build an ultrasonic filter with a regeneration effect and to increase its efficiency, it is necessary to create a calculation method that will take into account both the impedance of electro-acoustic emitters and the complexity of the geometric shape of the cavitation chamber. Development of calculation methods. The proposed method for calculating the geometric dimensions of the acoustic resonance system of the modular section of the tubular ultrasonic cavitator, which is excited by folded piezoelectric drive-emitters, which carry out longitudinal vibrations and are installed on the outer surface of the tubular vibrator. Simulation results. The results of modeling in the Abaqus Student Edition 2018 software environment are presented, confirming the possibility of creating ultrasonic flow cavitators, the vibrator, which are excited in a radial-flexion mode of vibration, for the technological process of ultrasonic cavitation filtration with the regeneration effect. Conclusions. The proposed calculation technique allows designing cylindrical ultrasonic cavitation filter chambers with a regeneration effect. Repeated practical verification of the presented method for calculating resonant acoustic systems has confirmed its sufficient accuracy under the applied assumptions.

2020-09-30T00:00:00+03:00 Copyright (c) 2020 O. F. Luhovskyi, A. I. Zilinskyi, A. V. Shulha, I. A. Gryshko, A. D. Lavrinenkov, O. S. Haletskyi, O. P. Zavalii