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Laser Doppler anemometry
Osička, Tomáš ; Lízal, František (referee) ; Jedelský, Jan (advisor)
This bachelor thesis deals with laser Doppler anemometry (LDA). It is a modern, non-intrusive flow measurement technique. The work deals with theoretical principles and components of the method. The experimental part is devoted to setting of the system. Vector plot and profile plot display the measurement results.
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Modulations in PLC systems
Procházka, Vít ; Kouřil, Jiří (referee) ; Krajsa, Ondřej (advisor)
The bachelor thesis describes principles and methods of Powerline Communications, practical usage possibilities both in industrial applications but mainly in broadband systems that may represent promising competition to conventional broadband access, e. g. xDSL connections without the need of new wiring, WIFI etc. The thesis also focuses on problems that can occur in the communication channel from the view of electromagnetic compatibility and assorted interferences. The 50 Hz frequency electric network (60 Hz in the USA) was not designed for data signal transmission, problems may arise mainly at higher frequencies and broadband communication. It is necessary to implement methods which enable transfer of information signal through a communication channel with minimalization of problems such as interference, cable attenuation, electromagnetic compatibility, bit error rate (BER), etc. Furthermore, currently used modulation principles and their characteristics are described, such as spread spectrum modulation DSSS, FHSS, traditional OFDM, alternative modulations FMT and DWMT with filter banks. The last chapter of the bachelor thesis features models of particular modulations created in the Matlab-Simulink program and the conclusion presents advantages and disadvantages of their implementation in PLC systems.
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Crosstalk analysis and modelling
Novotný, František ; Mišurec, Jiří (referee) ; Zeman, Václav (advisor)
The thesis concerns the problem of interference modelling for xDSL technologies and Ethernet. The introduction describes the origin of crosstalk, that arise during the operation of the systems and the physical properties of the lines, therefore, the next section describes the properties of the primary and secondary parameters of the homogenous line and their modelling. In order to achieve higher data rates on the metallic line, systems with larger frequency spectrum are applied, resulting in a greater attenuation of the line. This issue and the characteristics determination of the transmission systems are subjects of the mathematical models, which are divided according to the modelling of primary or secondary parameters. The main goal of this work is to describe the effects which influence the performance of data transfer via xDSL and Ethernet technology focusing on internal and external disturbances acting on the cable lines. This is the crosstalk at the near and far end, adaptive white noise, radio frequency interference RFI and impulse noise. Following part of the thesis deals with the properties of xDSL technologies, specifically ADSL2+ and VDSL2 and Ethernet. Another aim is to design applications which enable to test the performance of xDSL and Ethernet transmission systems with its own award simulations interference. The conclusion describes the design and implementation of laboratory experiments for measuring of the efficiency and spectral properties of xDSL. The proposed laboratory protocols are annexed to this thesis, including the measured waveforms.
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Analysis of an Electromagnetic Wave on the Boundary between Electromagnetic Materials
Kadlec, Radim ; Lazar, Josef (referee) ; Macháč, Jan (referee) ; Kroutilová, Eva (advisor)
The proposed dissertation thesis contains an analysis of conditions on the boundary between layers having varied electromagnetic properties. The research is performed using consistent theoretical derivation of analytical formulas, and the underlying problem is considered also in view of multiple boundaries including the effect of the propagation of electromagnetic waves having different instantaneous speed. The author presents a survey and formulation of the basic characteristics of methods used for electromagnetic wave propagation analysis; in this respect, special emphasis is placed on radial models. The processing of the topic involved the designing and verification (using a set of different, layered planar materials) of algorithms to analyze the electromagnetic field components. The algorithm was assembled to enable simple evaluation of all components of the electromagnetic field in relation to the speed of the wave propagation in a heterogeneous environment. The proposed algorithms are compared by means of different numerical methods for the modelling of electromagnetic waves on the boundary between materials; moreover, electromagnetic field components in common points of the model were also subject to comparison. When in conjunction with tools facilitating the analysis of material response to the source of a continuous signal, the algorithms constitute a supplementary instrument for the design of a layered material. Such design enables the realization of, for example, recoilless plane, recoilless transition between different types of environment, and filters for both optical and radio frequencies.
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Coexistence of DVB-T2 and LTE in the 800 MHz band
Walach, Dominik ; Miloš, Jiří (referee) ; Polák, Ladislav (advisor)
This bachelor thesis deals with the study and evaluation of coexistence scenarios which can occur between DVB-T2 and LTE systems in the UHF band 800 MHz Both DVB-T2 and LTE systems are briefly described, and their common frequency bands are defined. An appropriate laboratory workplace is proposed and realized for the measurement, analysis and evaluation of the DVB-T2 and LTE coexistence scenarios. These systems work in adjacent or even in the same frequency bands. Thereby these systems can coexist, and different coexistence scenarios can occur.
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Power distribution network model
Bradáč, Lubomír ; Mišurec, Jiří (referee) ; Mlýnek, Petr (advisor)
The thesis is focused on PLC technology issues and thus the data transmission over a power-line. This work describes characteristics of the PLC technology, its usage, functional principles and used modulation techniques. The main part of the work describes individual kinds of interferences in the network. The method of necessary steps against these interferences by using the right modulation and relevant coding is also described in the thesis. On the basis of theoretical knowledge, the models of interferences are realized in Matlab/Simulink. The simulative model of power-lines with random parameters is designed and realized for each elected techniques of modulation (BPSK, QPSK, ASK, FSK). The method of PLC channels modeling is chose as a multipath signal spreading for topology with one and two branching and the dependence of their transmission functions are inquired too. The analysis of interference influence on the data transmission is performed via the created models. All acquired results are compared and evaluated in the conclusion of this thesis.
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Variable Two-Way Loudspeaker Cabinet - Laboratory Tool
Rehák, Jan ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
The objective of this work is to build a two-way loudspeaker system that will enable changing loudspeaker topology in both vertical and horizontal axes and to suggest two laboratory tasks. The theoretical part of this work will briefly discuss loudspeaker crossovers. Then it will discuss how topology of loudspeakers in a loudspeaker system can affect its behavior at crossover frequency. Frequency characteristics of various loudspeaker baffles will be shown. On these, the effect of a baffle’s exterior on its behavior will be discussed. A two-way loudspeaker system will be designed. The construction process and drawings of each part are also included in this work. The finished product will be tested and, following from these tests, a conclusion will be drawn about the validity of the theoretical assumptions of its design. After that, appropriate parameters of a crossover for the two-way loudspeaker system will be chosen.
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Design Rules for Electronic Systems with ATMEL Microprocessors from the EMC Point of View
Kaštan, Jiří ; Svačina, Jiří (referee) ; Urbanec, Tomáš (advisor)
This diploma thesis is dealing with the basic knowledge of the Electromagnetic compatibility. It’s concretely target on electromagnetic interference flowing from the application of electronic gas control by Honeywell company. Author compile the power control board with including software in language C. The next alternates of power control board with the separated microprocessor were designed for the more extended source detection. On these boards there were explored shielding surface features placed directly under the microprocessor. The application reducing the interference was designed in accordance to the rules finding out during this diploma thesis writing.
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Intelligent control of train track model
Prokš, Jiří ; Hégr, Ondřej (referee) ; Pavlík, Michal (advisor)
The aim of this thesis is design of elements intelligent control of train track model. The first part of the thesis is focused on principle of data communication. It explains what it is data communication and how it works out. Practical part of the thesis is focused on designe of communication. Data communication is realized by infrared radiation. Practical part describes the funcional parts of system and their design, such as: control part, receiver and transmitter, switching elements and h-bridge. Properties of elements specialize for model of railway are considered in design. Summary of the design’s parameters, use, advantages and disadvantages are described at the end of this thesis.
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Angular velocity measurement with fiber optic interferometer
Sodomka, Pavel ; Šedivá, Soňa (referee) ; Havránek, Zdeněk (advisor)
This bachelor thesis deals with the proposal and implementation of optic-fibre interferometer using the Sagnac phenomenon which measures the angular speed. In the theoretical part of this work, the possible interferometers are closer described and specified, base of wave interference, problems of the rotatory movement. The Sagnac phenomenon is explained and described here. Further the possible constructions of the optical-fibre interferometers for the measurement of the angular speed, including the described errors, which prevent the correct assembling and the implementation of the sensor. In the practical part of this work, the optical-fibre interferometer with the minimal balanced configuration. The individual optical and optical-fibre elements are selected and described to the given configuration, such as the source of radiation, polarizer, controller of polarization, divider, phase modulator, isolator, detector, optical fibre and optical-fibre coil. There is the specified and based problem which did not allow to successfully finish the assembled optical-fibre interferometer. In conclusion of this work there is the recommendation how to solve the caused problem.
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