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Web applications supporting education of audio signal processing
Malcher, Tomáš ; Mokrý, Ondřej (referee) ; Rajmic, Pavel (advisor)
This bachelors thesis deals with a creation of web applications using JavaScript language. These web applications should be helpful in signal processing classes by showing and explaining different phenomenons to students. Students can see how different parameters affect the outcome of said issue. The theory needed for understanding and implementation is covered by this thesis. Thesis covers key parts of the code of said web applications and the libraries used for their implementaition.
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Optical signal detection and maesurement of low deflections using the Michelson interferometer
Kováč, Petr ; Hudcová, Lucie (referee) ; Křivák, Petr (advisor)
The dissertation is concerned with the description and utilization of interference of two coherent optical rays. In addition, the conditions of coherence and its connections with the occurance of interference are discussed. Michelson's interferometer is used for the practical utilization of the interference effect. The possibility of measuring relatively small changes is demonstrated - deviation of piezocrystal, measurement of the coherent length of optical source and measurement of the index of refraction of tramsparent materials. The manner of optical coherent detention and its utilization in optical communication systems is indicated. After demonstration of the principle was carried out the measuring of detection of optical signal modified by the external modulator.
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Vectoring in xDSL systems
Rada, Dominik ; Číž, Radim (referee) ; Šilhavý, Pavel (advisor)
This bachelor's thesis presents the approximation of VDSL2 and G.fast transmission systems according to pre-selected cable types. The thesis is also focused on the principle of vectoring and its use. The components of the thesis are explained by initialization process in modems with support of vectoring and approximation of Pre-Coder algorithms. A part of the thesis is a created user application in MATLAB, which displays the influence of vectoring on the transfer rates based on user input. In addition, the application captures primary and secondary line parameters, transmission characteristics, and transmitted masks.
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A Method to Supress Interferences in Wigner-Ville Distribution
Pikula, Stanislav ; Pazdera, Luboš (referee) ; Hájek, Karel (referee) ; Beneš, Petr (advisor)
The doctoral thesis focuses on signal representation in the time-frequency domain with constant resolution. In theoretical introduction the possibilities of displaying a signal in time and frequency are summarized. Attention is concentrated on comparison of short-time Fourier Transform (STFT) and Wigner-Ville Distribution (WVD). The latter achieves a significantly better resolution, especially for a linearly modulated signal. The disadvantage of WVD, which is the presence of interferences resulting from the calculation of the instantaneous autocorrelation function, is described in detail. These interferences are due to the presence of multiple components in the signal or its non-linear modulation. Subsequently, several methods are discussed, which can suppress these interferences, but at the cost of resolution loss. One of the interference suppression methods is smoothed pseudo Wigner-Ville distribution. It is further used in this thesis for the analysis of interference suppression when various filtrations in the time-frequency plane are applied. Several signals with multiple components or various non-linear modulations are used. Based on the analysis, a method using a set of variously smoothed pseudo Wigner-Ville distributions is designed to estimate the time-frequency representation with high resolution and minimal interferences. To compare the results to other methods, the quantitative metrics used in the literature are compared. To select the appropriate one a new metric is suggested. It is applicable to simulated signals and uses mean square error. Based on the comparison, the Stankovi\'{c} measure is selected as the most appropriate for comparing results. The selected metric is used to determine the appropriate minimal number of differently smoothed pseudo Wigner-Ville distributions. Using the selected metric, the proposed method is compared with other methods. These are STFT with optimized window length, S-method with optimized parameter and optimization method using radial Gaussian kernel (RGK). These methods are compared based on the set of signals previously used for interference suppression analysis. In addition, noises are added to the signals. Finally, the methods are also compared based on the real bat echo signal. In conclusion, the proposed method outperforms the compared methods in suppressing interference and resolution.
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Radiation pattern shaping of the optical transmitter
Csonka, Gábor ; Němeček, Jiří (referee) ; Wilfert, Otakar (advisor)
This work deals with questions of space assembling of several optics beams. There are mentioned the base features and values of space distribution of beam intensity in laser beam. The forms of diffusion of space localized light that is described by beam optics. There is a characterization of Gaussian beam, and diffraction of several beams. There is mentioned a simulation an assembling of two and more beams. It contains model of assembling incoherent beams. The work also includes suggestion of final layout of laser beams, which form optical transmitter with radiating characteristics, resistant to defects evoked by atmosphere.
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Coexistence of the communication systems in ISM band
Nowak, Dan ; Kejík, Petr (referee) ; Prokopec, Jan (advisor)
The purpose of this work is to study the physical layer technology of the communication systems working in the ISM band, to describe coexistence mechanisms in the selected frequency band, consequently to create models of the physical layers in the Simulink interface, to simulate synchronous transmission of the devices and to modify the model in order to correspond with coexistence mechanisms described in IEEE standard 802.15.2. The practical part of this paper examines the effect of Wi-Fi device output power on the transmission speed during synchronous transmission with Bluetooth device.
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Coexistence of wireless systems LoRa and Bluetooth
Paul, Filip ; Kratochvíl, Tomáš (referee) ; Polák, Ladislav (advisor)
Bakalářská práce je zaměřena na koexistenci LoRa a Bluetooth technologií v bezlicenčním 2.4 GHz ISM pásmu. Práce se skládá ze dvou hlavních částí, jmenovitě teoretické a experimentální. Ve své teoretické části se věnuje popisu fyzické vrstvy obou systémů a definuje koexistenční scénáře, které mohou mezi oběma systémy nastat. V experimentální části je navržen a zrealizován měřící testbed pro měření koexistenčních scénářů, které mohou nastat mezi LoRa a Bluetooth systémy v 2.4 GHz ISM pásmu včetně následného zpracování naměřených dat. Na závěr je navrhnuta laboratorní úloha a založená na experimentální části diplomové práce, která slouží pro edukativní účely pro kurz mobilních komunikací vyučovaný na univerzitě VUT.
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Dynamic laser interferometer
Chovaneček, Libor ; Drexler, Petr (referee) ; Fiala, Pavel (advisor)
The theme of this bachelor´s project is dynamic laser interferometer. The project is firstly focused on theory, where it explains the term of interference and principle of operation of interferometer on specific types of interferometers. Different types of lasers used in interferometers are mentioned there. The next part of this paper is focused on assemblage of interferometer with description of particular parts. There are mentioned two methods of signal processing. The last part deals with confirmation of proper functioning of measuring system.
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QoS optimization and modern communication services delay analysis
Novák, Přemek ; Škorpil, Vladislav (referee) ; Endrle, Pavel (advisor)
This thesis consists of theoretical and practical parts. The theoretical part contains an analysis of the problems of wireless networkssolutions individual standards and methodologies to ensure quality of service. In the practical part using the OPNET Modeler, a number of different simulation models and their evaluation. It is a model of individual standards, support mobility and interference effects on quality of service.
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Computer modelling of data transfer over power lines
Křivka, Petr ; Mlýnek, Petr (referee) ; Mišurec, Jiří (advisor)
The master‘s thesis is focused on data transfer over power lines. The influence of connected devices on data signal is studied. In this thesis, you can find the descriptions of PLC technology characteristics, sources of signal interruption and, mainly, the method of modelling the PLC channels as a multipath signal propagation environment is thoroughly discussed. There are models of PLC channels using this method projected in Simulink. The analysis of the influence of connected devices to bit error rate of a signal is processed. The devices are modelled by connected impedance.
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