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Spread spectrum modulator
Lejsková, Alena ; Kováč, Michal (referee) ; Maršálek, Roman (advisor)
This thesis deals with a method of spectrum-spreading of the data signals transmitted in the radio channel. There exist three different ways of spreading application, they uses pseudorandom sequences and also orthogonal sequences. In these systems we can find various kinds of modulations, one of them (Quadrature Phase Shift Keying) is shown at the end of the thesis. Spectrum spreading orthogonal multiplex OFDM is based on this method. The thesis wants to present the principle of the spectrum spreading method and the description of systems, transmitters and receivers that are using this method.
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The OCDM system model
Sekanina, Tomáš ; Miloš, Jiří (referee) ; Maršálek, Roman (advisor)
Master thesis The OCDM System Model is focused on problematics of multi carrier modulation techniques and in detail analyses the OCDM system. The first part of the work contains theoretical and mathematical description of digital communication system in general. The next part focuses on OCDM system and Fresnel transform, whose discrete form is kernel of the system. Digital model of the OCDM system is realized in programming language MATLAB. In the digital model is performed simulation of information from transmitter to receiver in AWGN and fading channel. The results are evaluated from the viewpoint of the system resilience against errors and achievable system throughput. The end of the master thesis is dedicated to mutual compatibility and comparison between OCDM and OFDM system.
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THE REDUCTION OF SIGNAL DYNAMIC IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEX SYSTEMS
Urban, Josef ; Lúč, Andrej (referee) ; Galajda,, Pavol (referee) ; Maršálek, Roman (advisor)
This doctoral thesis is focused into the area of multicarrier radio communications systems. These systems are perspective for current and incoming mobile communications and wireless networks. Advantages of multicarrier systems like better multipath propagation resistivity are redeemed by some disadvantages. The high peak to average power ratio of transmitted signal belongs to these disadvantages, for its inconvenience for high efficient power amplification. The thesis concerns with peak to average power ratio reduction methods for OFDM systems, that belongs to the most used multicarrier systems. One of the main objectives is the modification of the existing methods with the intention of complexity reduction. Following subject of interest is the analysis of suitable methods combinations possibilities for more significant peak to average power ratio reduction. One part of this thesis is research of influence of these methods on the OFDM signals with different parameters.
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Study of Lignite Organic Matter
Doskočil, Leoš ; Maršálek, Roman (referee) ; Havelcová, Martina (referee) ; Pekař, Miloslav (advisor)
This work deals with the study of organic matter in the South Moravian lignite using the available physico-chemical methods and the results obtained are eventually considered for non-energy applications of lignite. Lignite organic matter was studied by degradation methods, which included CuO oxidation, thermochemolysis with TMAH and DFRC method. Special attention was paid to the lignite oxidation with hydrogen peroxide, which was carried out under different reaction conditions (time and temperature). Thermal degradation was performed in an inert atmosphere in order to observation of chemical change of lignite (including lignite after extraction with chloroform, demineralised lignite, remineralised lignete) during pyrolysis by means of various methods, especially TG-FTIR for analysis of gaseous products and FTIR for analysis the residual lignite after pyrolysis. Further, water-soluble fractions from lignite were characterized, particularly in terms of the content of organic substances.
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Methods for quadrature modulator imbalance compensation
Povalač, Karel ; Valenta, Václav (referee) ; Maršálek, Roman (advisor)
Quadrature modulator (demodulator) is used in transmitting (receiving) part of many devices. Unwanted imbalance can influence amplitude, phase or DC offset of modulator (demodulator). Correction of imbalance was a main subject of thesis. Simulations of these methods were created in MATLAB and results were compared. Basics of methods were implement on programmable logic field by program Xilinx ISE. Development kit V2MB1000 with analogue board Memec P160 was chosen for this purpose. In the last part were compare simulation results with practical measurement.
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ZigBee implementation for Automotive Industry
Zatloukal, Martin ; Maršálek, Roman (referee) ; Prokopec, Jan (advisor)
This bachelor’s thesis describes possibilities of usage of ZigBee communication protocol in automotive industry, transport and logistics. Thesis also deals with ways of practical implementation of ZigBee protocol including typical cases solutions, designing and realization of necessary electrotechnical devices and modules followed by compilation of control software and experimental measurements of these devices in real traffic flow. In the first part of thesis, there are some basic features and parameters of ZigBee reminded, followed by ways of ZigBee communicator usage description and adumbrating how to perform integration with existing practical systems. The second part is about analysis of ZigBee data system construction, communication system scheme design and pre-projection of block schemes of its particular cells. The third part concretizes requested functions and features of these cells and describes ways of its hardware realization. The fourth section describes controlling software design, connection and controll of functions using PC and additional programs, using of X-CTU software offered by MaxStream Company to set up XBee parameters and using of AVR Studio 4 offered by Atmel Company to set up ATmega16 processor. The last part is taken by completation of hardware and software, tests with a few of XBee chips and network nodes in laboratory conditions and examples from the real traffic range measurement.
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Fading channel hardware simulator
Pirochta, Pavel ; Kováč, Michal (referee) ; Maršálek, Roman (advisor)
Fading channel is a communication channel that experiences different interference and fading due to multi-path signal propagation. The fading channel is designed by the finite impulse response filter with the time-varying impulse characteristic. The realisation of this filtr is based on the TDL (Tapped Delay Line) model, which simulate signal delay and signal attenuation in each branch. The aim of this thesis is to create the VHDL design of selected fading channel simulator and its description for hardware implementation into the FPGA.
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Non-energy Applications of Lignite
Majzlíková, Petra ; Maršálek, Roman (referee) ; Janoš, Pavel (referee) ; Pekař, Miloslav (advisor)
This thesis deals with various physical-chemical aspects of agricultural and environmental applications of the South Moravian lignite. The main attention was paid to the behavior of lignite in an aqueous environment and the application potential of lignite as a cheap, effective and universal sorbent. In the experimental part of the thesis, aqueous extracts of lignite were characterized in detail (by measurement of pH, conductivity, and by the qualitative and quantitative determination of inorganic constituents). The high sorption affinity towards polar (cationic dyes) and nonpolar compounds (petroleum products) was confirmed experimentally. At last, simple methods of the laboratory preparation of lignite granules was designed and optimized. The main aim of this part was to combine the unusual sorption properties of lignite with an improvement of the end-use properties of the product (user-friendly handling, controlled release of the lignite into the aqueous environment, etc.). The thesis represents a complex compilation of the results of pilot experiments which represent the starting point of detailed future works focused on the non-energetic application of this valuable natural material.
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