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A Contribution to Optimal Synthesis of Filters
Szabó, Zoltán ; Hájek, Karel (referee) ; Král, Bohumil (referee) ; Sedláček, Jiří (advisor)
The presented dissertation thesis is focused on the optimization of filtering circuit synthesis. In the five main sections of this work, the author analyzes partial problems related to several areas within the synthesis of modern filtering circuits. The first chapter constitutes an examination of elementary aspects which characterize present-day integrated circuits in voltage feedback operational amplifiers, and this main content is further complemented with a view on possible application of these circuits for the designing of filtering circuits as proposed within subsequent parts of the thesis. In this context, the second chapter contains a description of the design and optimization of digitally controlled universal filters tunable by means of digital potentiometers originally produced for audio technology. These digitally controlled circuits are increasingly utilized as analog preprocessing blocks in digital signal processing systems. The most extensive portion of the dissertation is dedicated to a complex analysis of individual configurations of economical, purposely lossy active function blocks and modern voltage operational amplifiers. This part of the thesis aims at providing a detailed insight into the characteristics of individual configurations of examined circuits; furthermore, in this respect, the author proposes a comparison of various application possibilities relating to these circuits and their wider use in the field of active frequency filters optimization. The described section of the work also includes a definition and examples of application of the designed and realized program, which facilitates significant simplification of purposely lossy ARC filters. In the penultimate part of the dissertation thesis, the design, development, and verification of a suitable synthesis procedure are presented together with the optimization of data and (in particular) power models of EMC filters. Based on the verification of characteristics inherent with the designed models of EMC filters, the suggested measuring procedure related to these filters is described, including the design of a station for measuring elementary parameters of line anti-interference devices up to very high frequencies. In the last section of the thesis, the author discusses the procedure of air ions concentration measurement through an aspiration condenser and analyzes the systematic and random errors as well as the optimization of filtration characteristics of the applied measurement method. This part includes the description of the design and characteristics of the realized fully automated measurement system with an aspiration condenser.
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Impedance spectroscopy of organic conductors and semiconductors
Černošek, Michal ; Sedláček, Jiří (referee) ; Hubálek, Jaromír (advisor)
This thesis deals with organic materials and determining their electrical parameters. In the thesis are discussed methods of deposition of organic layers and their measurement. Described are the aspects, which are characteristic for organic materials. They will briefly mention some new components and commercial systems. Special attention is given to conducting polymers and determining their parameters. In the experimental part were measured VA and impedance characteristics of the conductive polymer PEDOT-PSS. The research was also about material degradation in time and effects of thickness on the electrical parameters.
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Precise universal timer
Bohátka, Jan ; Murina, Milan (referee) ; Sedláček, Jiří (advisor)
Nowadays the precision of the time is highly required. Often not even the user is aware of the possibility to use different services thanks to the fact that the time is synchronized by some means. There is a plenty of possibilities how to keep exact time: through the use of atomic clock, by synchronization through the internet, radio after as much as the GSM, DCF. The signal DCF77 that is available in a great part of Europe is precise enough for most of the common goods and services. The signal is broadcasted from long-wave sender in Germany located not far from Frankfurt. In the thesis I described possibilities of the DCF signal reception and proposed the device able to decode the signal. For the usage and the configuration of the device a PC is required, after the configuration the device is able to work without a connection to the PC. Module enables to switch on and off four uniphase devices into tension 230V and electric current 10A. The most important part is microcontroller Atmega8 that decodes an signal, switches off and on the loads and operates the clock. Atmega8 does not contain USB port so for a comfortable communication it was necessary to complete the module by a converter RS232 USB. Software of the microcontroller is programmed in C-language and the AVR Studia environment. Application control is designed in C#-language and the Visual Studio 2005 Professional environment.
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ARC filters with modern active elements
Sedláček, Petr ; Murina, Milan (referee) ; Sedláček, Jiří (advisor)
The aim of this project is to compare the characteristics of low pass and high pass filters designed by various methods of synthesis. Firstly, the attributes and characteristics of filters and realisations of higher order filters using normed low pass filter and approximation of gain-magnitude frequency response are described and then used in application. The circuits that substitute coils directly or undirectly using the Bruton transform are discussed next. The practical part of project concerns of design of high pass and low pass itself, using two methods of synthesis. Proper real operational amplifier has to be choose for used frequency. In the final part of work the designed circuits were realized and their characteristics were measured and examined.
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Adaptive antialiasing frequency filter
Sovadina, Václav ; Murina, Milan (referee) ; Sedláček, Jiří (advisor)
The aim of this project is to become acquainted with the Bessel approximation function and to present the possible connections of the adaptive antialiasing filter. Then, cascade and partition filter realizations are designed and their computer analysis are carried out. Furthermore, the thesis deals with the options of electronic realignment of filters. A common connection of digital potentiometer along with the block diagram of the whole mechanism are described. The next part presents a construction of the analogue part of the filter, measuring of its real characteristics and the control circuit for the analogue part.
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Electronic circuits with active elements at current mode
Bačkovský, Pavel ; Sedláček, Jiří (referee) ; Murina, Milan (advisor)
This bachelor’s thesis deals problems with current feedback amplifiers and their comparison with voltage feedback amplifiers. Then it adverts to mutual differences and compares their parameters. This thesis shows basic circuits with current sources and with power boost of this circuits. This thesis designs conception of current source. Simulation, complete details for realization of current source, drawing printed circuit and specification card used parts are part of this work. In the end this work the parameters of current source are checked.
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Biosensor of halogenated substances as device using fluorescence method
Sedláček, Jiří ; Prokop,, Zbyněk (referee) ; Hubálek, Jaromír (advisor)
This master thesis deals with design and construction of device for optic biosensor. The device are using for detected halogen compound in the water. For excitation testing sample is used LED diode about wave length 590 nm. Photocounter is used for detection of the emitted light after fluorescence Such as fluorescent marker are 5(6)-carboxynaphthofluorescein. The thesis is divided into three head parts. The first part includes the theory needed for realization; the second part takes in detail description of the construction and function of the device and the last part describes measurements with the device.
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Digital conversion of analog signals
Čermák, Petr ; Sedláček, Jiří (referee) ; Murina, Milan (advisor)
My work is focused on digital elaboration of the analog signal. In my work the analysis has been carried out in all parts of digit chains processing analog signal. The entranced variable is signal from measuring coil, which is afterwards strengthen and transfer to a sampler. The sample signal is processed by an A/D converter and then sends to a parallel port. On the basis of acquired data the scheme has been constructed for sample processing. The transfer to the parallel port is done (made) in two steps, at first one part of the word is transferred and then the rest of the word follows. Between the converter and sampler is tight relationship and synchronization. Both of them are managed from one central bus.
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Adaptive active band - pass
Velička, Pavel ; Murina, Milan (referee) ; Sedláček, Jiří (advisor)
The aim of this thesis is to find and propose solutions adaptive ARC frequency bandpass filter, where it will be possible to change the bandwidth and tuning the center frequency. Centre frequency will be tuning in the range from 10kHz to 100kHz. Bandwidth is tunable to the maximum range that will enable us to select involvement. The thesis selected two methods of implementation of the filter. It made the comparison and selection of improved variants. Thesis includes calculations of the resulting variant filter and describes how to tune the filter, and then simplify the tune selected filter. Bachelor thesis includes a complete filter design for its implementation. A suitable method of electronic tuning were selected digital potentiometers controlled programmed microcontroller. This method was also subsequently implemented.
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Trust in the Czech Republic
Filipová, Silvie ; Sedláček, Jiří (referee) ; Brychta, Karel (advisor)
The diploma thesis „Trust in the Czech Republic“ deals with new institute in Czech law legislation. The first part is focused on theoretical knowledge of the Trust Fund, it is history and similar institutions based abroad. The second part deals with the process of establishment of the Trust and show methodical instructions for the system of taxation of income related to the operation of the Trust Fund.
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