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Tunable ARC frequency filter
Kufa, Martin ; Murina, Milan (referee) ; Sedláček, Jiří (advisor)
This bachelor thesis deals with ARC frequency tunable filters. The introductory chapter generally focuses on the basic terms of the frequency filters, such as the mathematical expression of the transfer function, types of selective filters, tolerant field, etc. The next section describes the actual higher-order ARC filters and cascade sequencing, especially ARC band reject and possibilities of its implementation. Following is a concrete realization of the ARC filter to band reject with suggestions for tuning the frequency components in the frequency range 10 kHz to 100 kHz and retuning quality factor. Finally, this work contains the printed circuit board (PCB) design of the ARC frequency analog and digital filter section for tuning F0 frequency and quality factor Q setting using digital potentiometers. Furthermore, it also outlines the flowchart of the program for digital control.
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Synthesis of Modern Structures of Frequency Filters
Friedl, Martin ; Hájek, Karel (referee) ; Brančík, Lubomír (referee) ; Sedláček, Jiří (advisor)
Within modern frequency structures, the filter frequency region of up to 10 MHz constitutes a promising research topic that currently attracts intensive attention of specialists interested in the problem. The main reason of this fact consists in that the rapid development of modern technology allows the production of innovated structures of the analog frequency filters required in the defined band. In this context, however, it is also necessary to refine the methods applied in the synthesis and optimization of these structures; such improvement should be carried out with respect to fundamental properties and usability of today's active elements (operational amplifiers with voltage feedback whose Gain Bandwidth Product ranges within units of GHz, operational amplifiers with current feedback, conveyors, transimpedance operational amplifiers). In this thesis, active blocks of synthesis inductors (SIs) and frequency dependent negative resistors (FDNRs) are examined in detail, and the author provides novel formulas to define the basic parameters of the dual circuits. Due emphasis was placed on optimizing the basic building blocks of the second order and defining the variation of their properties caused by the addition of modern active elements. The blocks were analyzed and modified in view of their possible use in higher-order circuits. For active filters of a higher order, simulations were performed to indicate the actual sensitivity of the cascade and non-cascade ARC structures. The following phase of the research comprised mainly the designing of several filters, and this activity was further completed with the verification of the methodology for the synthesis and optimization of higher-order loss ladder filters with modern active blocks. Special attention was paid also to the methods enabling the optimization of such filters, which are invariably based on RLC prototypes. In order to verify the theoretical conclusions, the author materialized a large number of sample optimized filters and measured their parameters. The closing section of the thesis describes the use of the filters in specific applications.
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The MEMS sensors usability for position detection
Bobalík, Lukáš ; Sedláček, Jiří (referee) ; Žák, Jaromír (advisor)
Within this Master’s thesis, design and construction of a strapdown inertial navigation system based on MEMS sensors is described. The thesis includes theoretic analysis of physics behind determining the position of an object based on the object’s aceleration and changes in the object’s orientation in space. Included is also an overview of mathematical methods related to the position calculation.
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Adaptive frequency filter
Dolák, Jan ; Murina, Milan (referee) ; Sedláček, Jiří (advisor)
This thesis deals with passive and active frequency filters and their realization. The mail goal of my thesis was to design, simulate and realize adaptive frequency filter with the possibility of alternating it's parameters. The designed filter should be an active band stop filter of fourth kind with the possibility of alternating it's resonance frequence f0 and it's coefficient of quality Q. At the beggining it was needed to study the theory of frequency filters, types of frequency filters, which are often used in praxis, their properties and ways of their realizations. Use of active filters with operational amplifiers was optimal possibility of their realization. Because of there was given them the biggest attention in this part of the thesis. Then it was searched the most acceptable solution of required band stop filter, witch would have the best properties. Digital potentiometers operated by microcontroller were chosen for setting different values of various parameters. Designed circuits were realized after the decision and adaptation of optimal wirings and then the programme for operating of microcontroller and digital potentiometers was configured. By this way designed circuits were experimentally measured.
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Ultrasonic distance measurement
Giemza, Michal ; Žák, Jaromír (referee) ; Sedláček, Jiří (advisor)
This thesis describes the design and realization of an ultrasonic distance meter. Is discussed about the principle of distance measurement using ultrasound and all physics laws, that occur during the measurement. It was selected the most appropriate measurement method, was also discussed about different types of ultrasonic transducers and was selected an appropriate converter for the specified task. The following part describes all function parts of the meter together with the processing of the detected ultrasonic signal. Next part is focused on the realization of the meter and programming, including the control of the graphical display and communication over the USB bus. The last part deals with the measurement with the completed meter to verify the functionality and the right choice of measurement method and circuit solution.
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RESONANT AND QUASI-RESONANT SWITCHMODE POWER SUPLIES
Vašina, Petr ; Sedláček, Jiří (referee) ; Murina, Milan (advisor)
This project focuses on issues and solutions to switch mode power suplies. The first part discusses comparison of analog and switching power supply stabilized, and their essential involvement. Further addressed the concept of peripheral participation resonant switch mode power suplies. This chapter is progressively designed input circuit, the main part of the switching resources, output circuit and feedback circuit comparison. At the end of the project is the komplete wiring diagram with a list of used parts. Under the proposal was designed printed circuit, is characteristics were measured.
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Integration of advanced artificial intelligence methods with log management security systems
Sedláček, Jiří ; Mikulec, Marek (referee) ; Safonov, Yehor (advisor)
Cyber security is a very important aspect of everyone’s daily life. With the ever-expanding cyberspace and its growing influence on the real world, the issue of cyber security is all the more important. The theoretical part of the thesis describes the basic aspects of security monitoring. Also, the process of collecting event logs and their management is briefly described. An important means of security monitoring is the management of security information and events. Its advantages, disadvantages and possible improvements with artificial intelligence are discussed. Security orchestration, automation and response functions are also mentioned in the theoretical part. Machine learning techniques such as neural networks and deep learning are also mentioned. This section also focuses on cyber operations centres in terms of improving the efficiency of human ”manual” labour. A survey of possible machine learning techniques for this use case has been conducted, as the lack of human resources is a critical issue within security operations centres. The practical part of the thesis involves setting out a goal (text sequence classification) that could make the work considerably easier in terms of manually categorizing event logs according to their source. For this set task, security monitoring related data was collected from different log sources. In the practical part, the methods for processing this data are also described in detail. Subsequently, a suitable neural network model was selected and its technical description was performed. Finally, the final data processing and the process of training, validating and testing the model are described. Three scenarios were developed for this process, which are then described in detail in the measurement results.
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Resonant and quasi-resonant converters
Krška, Vlastimil ; Sedláček, Jiří (referee) ; Murina, Milan (advisor)
Project is engaged in concept and realization of quasi – resonant converter with switching in minimum voltage which derive benefit from resonance capacitor and inductor. It is one of the possibilities how to increase efficiency of switch – mode power supply. While using resonant converters the losses are reduced, when the resonant inductor will connect and disconnect at zero current in inductor, or at zero voltage on inductor. Base of the power supply is chip NCP1337. Concept comes from detailed analysis functions of integrated curcuit and others curcuits of switch – mode power supply. Project includes a complete concept of all partial curcuits, description of a construction and the main parameters measured on the realized sample.
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Antialiasing frequency filter
Kocián, Daniel ; Murina, Milan (referee) ; Sedláček, Jiří (advisor)
The bachelor´s work deals with a project of the connecting of the antialiasing electronically turnable ARC filter of the low pass of the fifth order with the Butterworth approximation with the adjustable limited frequency FM in the extent 10 kHz – 100 kHz. The theoretical part includes a short summary and a description of constituent blocks of the complete device. Then the problems of the frequency filters are analyzed there. The practical part consists the project of the printed circuilts of all constituent blocks, then the calculation of all circuited components of ARC filter of the type of low pass for all limit frequencies of the filter. The result of the all work is a device which consists of five blocks and its core is the microcotroler ATmega16. For the electronic turnabling of the filter there are used digital potenciometers. The inseparable part is the enclosed CD-ROM which includes all made materials.
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