Вісники та науково-технічні збірники, журнали
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Item Метод підвищення енергетичної ефективності HQPSK сигналів(Видавництво Національного університету "Львівська політехніка", 2016) Бондарєв, А. П.; Максимів, І. П.; Максимюк, Т. А.Показано можливість зростання енергетичної ефективності систем коміркового зв’язку за рахунок зменшення порогового відношення сигнал/шум за заданої частоти появи бітової помилки, з використанням особливого типу квадратурної фазової модуляції (HQPSK) і модифікованого фазового детектора. Обидва методи мають і переваги, і недоліки. Комбінація цих двох методів теоретично може зменшити їх недоліки, роблячи їх вигіднішими, ніж наявні методи. With the development of cellular communications, the different problems of effective spectrum utilization to provide a high quality of service for large number of mobile users have been emerged. For the last years the development of wireless communications became a large scale, inducing developers of radiotechnic devices to find new solutions to the problem of effective utilization of the allocated spectrum and effective power maintenance. Many types of spectral-efficient modulation of radio signals and new protocols that enable efficient distribution of network traffic have been proposed so far. One of the key parameters that are used for channel efficiency estimation is signal-to-noise ratio (SNR): the higher SNR results in lower bit-error rate and vice versa. Dependence between bit-error rate and signal-to-noise ratio is the key characteristic of the communication channel and optimization of this characteristic is an important task for communication networks. This paper shows the possibility of reducing the signal-to-noise ratio while maintaining the required bit-error rate by using specific type of quadrature phase shift keying (HQPSK) complemented by modified phase detector. Both methods have their advantages and disadvantages. The combination of these two methods can theoretically reduce their cons while effectively exploiting their advantages. The feature of the first method lies in power saving approach, providing the use of only one quadrature component during signal modulation, while the second quadrature component is coded using additional frequency subcarriers. The second method allows detection of quadrature signals at high noise power condition. This benefit is achieved by implementation of specific narrowband filters into phase detector.Item Дослідження методів знешумлення інтерферограми білого світла(Видавництво Львівської політехніки, 2015) Хома, АннаПроаналізовано джерела спотворень інтерферограми білого світла. Обґрунтовано методику та досліджено ефективність знешумлення синтезованого сигналу інтерферограми з використанням цифрових фільтрів та вейвлет-перетворення. Результати апробовано на реальній інтерферометричній картині. Проанализированы источники искажений интерферограмы белого света. Обоснована методика и исследована эффективность фильтрации синтезированного сигнала интерферограмы с использованием цифровых фильтров и вейвлет-преобразования. Результаты апробированы на реальной интерферометрической картине. White light interferometry (WLI) is a non-contact measurement technique which is commonly used in determining the mechanical quantities such as geometric dimensions, position, and surface topography of the object. The main areas of use of the white light interferometers are micro- and nanotechnology, biomechanics, polymer chemistry, semiconductor equipment, and others. The measuring channel of optical interferometer includes the optical part and the computer unit. The accuracy of surface reconstruction depends on the quality of interferogram registration (optical part) and metrological properties of the reconstruction algorithm (computer unit). In practice interferogram registration is accompanied by different distortions, including optical nonlinearities and noise. Reduce of the distortions destabilizing effect can be achieved by processing the obtained interferogram in a computing unit by special algorithms. The aim of the work is analysis of methods for white light interferogram denoising. The article analyzes the distortion sources of white light interferogram and the ways of their processing. The technique of researchis based on analyzing the effectiveness of denoising the synthesized white light interferogram with signal-tonoise ratio of 30 dB. Quantitative parameter for evaluating the filtering effectiveness is signal-to-noise ratio. Firstly the researches were conducted on one-dimensional data (for the central line of interferometric pattern). This article examines the possibility of WLI denoising with digital filters (frequency domain) and wavelet transform (time-frequency domain). When using digital filters, the non-recursive filters were selected, as they are characterized by a linear phase response that will keep the shape signal. Filtering of interferogram signal using nonrecursive filter has not produced satisfactory results, as in one case with noise suppression the part of useful signalis damaged, and the signal-to-noise ratio was 15 dB. By increasing the cutoff frequency of the filter, signal shape does not undergo distortion, but there are some artifacts, especially in its central part. The reason is that the signal lies partly in the frequency dominated, where the noise predominates. The signal-to-noise ratio was 35 dB. Wavelet transform allows to decompose a signal to approximating and detailing components, with higher levels of detailing component responsible for scheduling and signal noise can be set to zero without signal distortion. Application of wavelet transformation made it possible to achieve better denoising results compared to digital filters with signal-tonoise ratio about 50 dB. Taking into account these results, the wavelet transform method is adapted to the two-dimensional data (interferometric pattern). Compared to the one-dimensional data the denoising is slightly lower, as evidenced by the signal-to-noise ratios about 40 dB. This is due to the fact that the interferogram signal intensity decreases as the distance from its center. The effectiveness of the denoising method based on wavelet transform was investigated on a real white light interferogram obtained for a spherical surface. Defects observed in the interferometric pattern after denoising are caused by optical distortions.Item Визначення області допустимих параметрів фільтрів у модифікованому детекторі сигналів із квадратурною модуляцією(Видавництво Львівської політехніки, 2015) Бобало, Ю. Я.; Бондарєв, А. П.; Максимів, І. П.У роботі описано результати імітаційного моделювання у програмі Matlab приймання сигналів з квадратурними видами модуляції, зокрема OQPSK, за умови використання модифікованого детектора фазомодульованих сигналів. У результатах наведено залежності відношення сигнал/шум до ймовірності появи бітової помилки модифікованого детектора та класичного детектора, на основі чого зроблено висновки щодо його ефективності. This paper describes the Matlab simulation results of receiving signals with quadrature modulation, such as OQPSK, using modified phase detector. As the result, the BER-to-SNR diagrams were presented for modified and classical detector. The conclusions about its effectiveness were made. There are new methods of modulation signals that allow effective use of the frequency band, and communication systems (eg. trunking) that can effectively distribute the network traffic. However, further development of communication systems is limited by threshold SNR, which is one of the determining factors for the calculation of the capacity of the channel. This paper shows the possibility of increasing noise immunity and capacity of modern cellular communication systems and trunking communication without increasing transmitter power. The improved PLL resistance to noise without changing of dynamic properties is implemented using a modified synchronous phase detector. The proposed scheme of modified PLL device differs from the classical analogue by the narrow band pass filters, placed before the detector, and high-band filter after it. The simulation processes of detection OQPSK signals which were used in modern systems such as cdma2000 were made. For as close as possible to the real analogue, the phase detector in imitation model was implemented with levelling filters. These filters are used in communication systems to reduce intersymbol interference that occurs in the digital channel. Research was carried out for the case of signal detection by classical and modified detectors. The aim of the research was to determine the bit-error rate (BER) in the received signal at a particular value of SNR. The obtained BER-to-SNR values for the classical phase detector were compared with similar ratios given in the open literature. The research results show that modified detector is more efficient than classical detector due to its higher noise immunity. As a result of simulation model of the modified detector research in Matlab program the recommendations for selecting detector filters parameters at high noise level were made. This makes possible to use them in the designing of modern phase demodulators. The modelling results show the potential for increasing the efficiency of existing cellular communications that use complex types of phase modulation with no additional energy costs. The results of modification using narrowband filters before detector of OQPSK signals can significantly improve its noise immunity and energy efficiency.Item Шляхи підвищення завадостійкості у системах коміркового зв’язку(Видавництво Львівської політехніки, 2012) Бондарєв, А. П.; Максимів, І. П.Здійснено імітаційне моделювання приймання OQPSK сигналів модифікованим фазовим детектором. Експериментально встановлено область значень параметрів детектора, за яких приймання сигналу відбувається належно під час впливу на сигнал високого рівня шуму, та знайдено відношення BER до SNR. This work presents the simulation of OQPSK signals receiving by modified phase detector. The area of detector's parameters values at which the receiving of signal works properly during high ratio noise influence was experimentally determined and BER-to-SNR ratio illustrated.Item Дослідження впливу шуму приймача випромінення на точність вимірювання температури за випроміненням багатоспектральними методами(Видавництво Львівської політехніки, 2010) Гоц, Н. Є.; Пянтковскі, Т.Розглянуто вплив шумів приймача випромінення на похибку пірометра у процесі його калібрування. Визначено математичну залежність між похибкою вимірювання температури та відношенням сигнал/ шум за різної кількості спектральних каналів пірометра, що досліджено за допомогою математичного моделювання.Eradiation receiver impact on the pyrometer error in the process of calibration has been considered in the proposed article. The mathematical dependence of temperature measurement error on signal/noise ratio at various amount of spectral pyrometer channels is determined by the modeling.