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SDR Signal Processing for Portable Monitoring Station
Svobodník, Petr ; Záplata, Filip (referee) ; Šebesta, Jiří (advisor)
Goal of this thesis is to develop portable monitoring station for radio spectrum monitoring and its controlling application for use by Czech Telecommunication Office. The station is based on Software Defined Radio (SDR) and capable of monitoring in the range of 1 MHz - 6 GHz. Developed application controls not only the SDR but also the external RF unit (including choice of receiving antenna, filter, optional amplification/attenuation and azimuth of antenna rotator). Measurement processed by computer and displayed graphically in form of spectrum diagram and waterfall diagram. Furthermore, the application will perform spectral measurement in compliance with requirements of International Telecommunication Union. The application is also capable of recording into the file and of analyzing historical data from the previous measurement.
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Hardware MISO Emulator for Fading Channels
Rez, Jan ; Pítra,, Kamil (referee) ; Šebesta, Jiří (advisor)
This thesis is devoted to study the possibility of solving a hardware MISO emulator for fading channels and design of experimental device. The theoretical part starts with the theory of propagation of electromagnetic waves in a different types of environment, follows the principles and phenomena describing the radiocommunication channels and gradually gets up to specific channel models used for planning radio links. The actual design study of emulator is based on theoretical knowledge mentioned in this thesis. The basic principle of each channel model and thus so the emulator for fading channels is Tapped Delay Line model. From the point of view of the peripheral emulator solutions are designed with two topology circuits, parallel and serial-parallel. Emulator control method, mechanical arrangement, selection of topology circuit, components selection, desing of the PCB and software design is also analyzed. The results of this thesis is prototype production of experimental device and final discussion about achieved requirements and tasks.
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Automatic Antenna Tuner
Šváb, Jaroslav ; Lukeš, Zbyněk (referee) ; Šebesta, Jiří (advisor)
This degree work deals with the design and implementation of an automatic antenna tuner for short-wave transmitters. The device works within the short-wave range in (1.5 MHz - 30 MHz) band according to the selection of the given frequency. Its principle is that the tuner has a small range of adapted impedances, but it is usually sufficient for fine tuning of most deviations in the system of antenna 50 - feeder 50 - transceiver outlet 50 . It is also equipped with memories which the settings for the individual bands or frequency segments are stored into. Then the transition from one band to another is quick, easy and, first of all, safe, which is a great advantage. In automatic mode, a SWR limit from which the tuner should start to tune can be set. Interconnection with a TRX is not necessary in a fully automatic mode, the device tunes automatically after keying if the set limit of SWR has been exceeded. The automatic tuning is very quick with this device, if the antenna being tuned is not stored in the memory the tuning lasts ca 0.5 - 6 s, if the tuner uses the memory. It could be said that the work with the tuner is without problems, it is possible to learn to control it in a short time. The tuner is small and light. The result of the whole project is a compact device controlled by the user by means of push buttons.
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Control system for lasertag weapon
Svozil, Martin ; Kubíček, Michal (referee) ; Šebesta, Jiří (advisor)
This thesis describes the design of equipment for Lasertag. The proposal is designed in cooperation with other collaborators on the project. This work is focused on gun unit and its components. The whole system will be implemented using the microcontroller, which subsequently controls the entire system with its components. The work should be implemented and tested to the thesis.
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DC-AC converter 12 V / 230 V for car applications
Jezerčák, Martin ; Šebesta, Jiří (referee) ; Brančík, Lubomír (advisor)
This work deals with a proposal for increasing DC/AC inverter for use in cars to power electronic devices on 230 V. This work is divided into two parts, theoretical and practical. It consists of three chapters. In the first chapter I developed a voltage converter, its breakdown, a breakdown by function, and the usage of individual connections. The proposal converter with the integrated circuit IR2153 is described in the second chapter. In the third chapter I processed readings and I visualized graphical dependencies of converter that was produced and purchased.
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Exhaustion control system
Bršel, Boris ; Šebesta, Jiří (referee) ; Fedra, Zbyněk (advisor)
Topic for my bachelor’s thesis is control system of exhaustion for wood industry. It´s very comprehensive issue, and since I am without bigger experience in this division I have chosen to create easier model of exhaustion system. I would like to continue in this project in master´s thesis too. My thesis consists in description the requisites for system like this, draft of the making and also practical making for joinery manufactory. I have decided control the parts of system by microcontrollers, which communicate with each other wireless and also decide about activity of parts of system of exhaustion in workshop like this. The role of this thesis was also to compare achieved results with other possibilities of control of exhaustion from the economic and technological site too.
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Measuring the velocity of projectiles by laser beam
Šmerda, Jaroslav ; Šebesta, Jiří (referee) ; Lukeš, Zbyněk (advisor)
Muzzle velocity is the speed of bullets, guns at the moment it leaves the barrel of a gun. Since this is a parameter related to the storyline, which takes place only shortly after the bullet leaves the barrel, this figure is the transition ballistics. The aim of this work is to design and construct a device for measuring the speed. Measurement consists in measuring the interval at which the bullet crosses the two laser beams. From this data, the performance will be calculated.
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Synchronization of measuring devices by optical fibres
Petr, Ondřej ; Šebesta, Jiří (referee) ; Dřínovský, Jiří (advisor)
The aim of this work was to get acquainted with the possibility of transmission of RF signals using optical cables. And design synchronization modules to transmit the reference signal, so that the source and the receiver of the signal are time-synchronized and mutually galvanically separated using optical cable. To transmit and receive optical signals through optical fiber, I chose the transmitter and receiver of the series HBR- 0400 the company Agilent Technologies.
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Laboraty Pulse Power Supply Using Output Linear Stabilization
Lednický, Marek ; Dušek, Martin (referee) ; Šebesta, Jiří (advisor)
This thesis deals with switched mode power supplies. The theoretic part of the thesis consists of historical development and the elementary schemes of switched mode power supplies. It also includes the comparing with linear regulators. Next, it contains the description of individuals parts switched mode power supplies as a rectifiers, power supplies and stabilizers. There is a proposal and fixing of laboratory pulse power supply using output linear stabilization in the practical part of the paper.
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Power amplifier for shortwave radioamateur bands
Smutný, Štěpán ; Šebesta, Jiří (referee) ; Lukeš, Zbyněk (advisor)
The amplifier is designed in the class AB, for which is typical acceptable efficiency and relatively low quiescent power consumption. As active components, the MOSFETs transistors are used. Their quadratic transfer characteristic allows for a gain control by means of quiescent current setting. The principle of MOSFETs function will be described, along with their utilization in the class AB amplifier. Since the amplifier processes signals in the shortwave band, parasitic capacitances of the transistors reduces gain greatly. Therefore, these capacitances will have to be compensated by positive feedback. First, the function of the amplifier will be verified in PSPICE program, then design or selection of real components (including transformers, heat sink and bias control) will be carried out. By performing measurement on assembled amplifier, we have verified the gain control (doubling the quiescent current increases gain by 3dB). If the quiescent current is set to 1250mA, the gain exceeds 20dB in the range from 1.4MHz to 13.5MHz. Gain at high frequencies was achieved thanks to compensation by positive feedback.
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