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Influence of magnetic and electromagnetic fields on signals transmitted by optical fibres
Schneider, Tibor ; Vrba, Kamil (referee) ; Münster, Petr (advisor)
The diploma thesis deals with the influence of magnetic and electromagnetic fields on signals transmitted by optical fibers. Subsequently, the results of individual measured values are evaluated and analyzed, which were measured using an interferometer and a polarimeter. The first part deals with the theoretical analysis of the principles of interference and polarization of light. It further explains the basic operation of the above-mentioned devices as well as the immunity of the optical fiber to EMI. The second part of the work presents selected devices and technologies that were used as a source of electromagnetic or magnetic radiation. Subsequently, individual phenomena are plotted both in the course of time and with the help of a spectrogram or Poincaré sphere. From the measured results we can conclude that the commonly available technologies, which were selected for the diploma thesis, will not cause greater negative problems to the signal on measured frequencies in optical fibre, that could degrade the transmitted signal.
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Antenna preamplifier for EMI measurements
Sedlák, Milan ; Urbanec, Tomáš (referee) ; Dřínovský, Jiří (advisor)
The master thesis deals with the design of a low noise preamplifier operating in the frequency range from 30 MHz to 1 GHz, usable for measuring and testing of electromagnetic interference in the electromagnetic compatibility test rooms. The introductory, theoretical, part is focused on the analysis and description of the necessary properties of the low noise preamplifier required for the subsequent design. The practical part deals with the selection of suitable components, simulation, design and subsequent realization of low noise preamplifier. At the end of the thesis the design and the final verification measurements are described and discussed.
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Coupling mechanisms of transmission interference
Chromý, Stanislav ; Vedral,, Josef (referee) ; Havlíková, Marie (advisor)
The primary focus of the Bachelor's Thesis is placed on description of dominant interference sources and coupling mechanisms of interference signals transmission from the source of interference into influenced system including main principles of minimization and elimination of interference impact on a system. A relevant part of the Bachelor's Thesis describes coupling mechanisms of interference signal transmission into a real cable system including derivation of theoretical coupling mechanism transmission and its subsequent verification by means of simulated non-harmonic signal measurement.
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Measurement and analysis of audio-frequency differential disturbances in distribution systems
Doseděl, Tomáš ; Havránek, Zdeněk (referee) ; Drápela, Jiří (advisor)
This thesis deals with voltage disturbances in audio-frequency propagated in distribution networks. In the theoretical part, a creation and effect of these interferences are discussed as well as current methods of their measurement. In the practical part of the thesis, a measurement device based on a frequency filter was developed. This measurement device is able to measure audio-frequency disturbances up to 250kHz without suppresion of audio-frequency disturbances. The maximum frequency on the output is limited by either 125kHz or 250 kHz filter.
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Optimum layout of workplaces security checks of passengers
Bordovský, Lukáš ; Janík, Radomír (referee) ; Šplíchal, Miroslav (advisor)
The final master’s thesis analyzes the individual elements of Security control workplace and solves their optimization with respect to the rulemaking side of things, and integration into the existing space layout with a vision of the increasing demand for transport. Solves the issue of electromagnetic interference elimination in the detection equipment and suggests possible solutions to overcome them. The work is primarily related to the Prague - Ruzyne airport.
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Pacemakers and electromagnetic interference
Lojková, Lea ; Sekora, Jiří (referee) ; Havlíková, Marie (advisor)
This work is focused on cardiac pacemakers and sources of electronic interference. The project partly follows another thesis made in the same field of interest (Ing. Kulík, Dept. of Control, Measurement and Instrumentation) and uses similar methodics of measurement. In the theoretical part of the work, the principles of nuclear magnetic resonance and magnetic resonance imaging are briefly explained and most common methods used in MRI are described, as well as the definition of a cardiac pacemaker, main events in pacemaker history and development. Cardiac pacemaker as a system is described in more detail, including construction, control, most common sensors and the ways of use. Electromagnetic interference of cardiac pacemakers and implantable cardioverter defibrillators is processed via a complete review since the oldest scientific paper from December 1991 till May 2009. In the second part, measuring of magnetic field is described, as well as the possibilities of monitoring of its effects on cardiac pacemakers. In fact, there are two possible ways of measuring. off-line exposition of the sample to the magnetic field followed by data acquisition via pacemaker programmer or the continuous on-line monitoring of the pacemaker activity by the means of measuring PC card. While the first method is reliable in cases where the is no sign of malfunction and makes the experiments with a dynamic exposition of sample possible, in some cases it detects a virtual malfunction also in cases where in reality the devices works perfectly. The second method enables a reliable continuous monitoring of pacemaker activity during the whole experiment and its only problem is a higher level of signal noise caused by the sample movement.
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Differential and Common Mode Conducted Emissions Measurement
Matýsek, Michal ; Soldán, Josef (referee) ; Dřínovský, Jiří (advisor)
This work deals with interfering signals and noises, possibilities of their measurement, their reduction and afterwards with design of LISN. The theoretical part analyzes formation of interfering signals, their types, with possible measuring instruments for each type of these signals and their properties. In framework of practical part LISN for long-term load of 5A, frequency range from 150 kHz to 30 MHz, with possibility to measure symmetrical and asymmetrical noise separately and also with possibility to switch to normal mode of LISN was developed. For better results LISN was realized as two stage LC filter.
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Measurements of electromagnetic interference in anechoic and semi-anechoic chambers
Deneš, Roman ; Růžek, Václav (referee) ; Dřínovský, Jiří (advisor)
This thesis is focused on a detailed analysis of the mechanisms of electromagnetic wave propagation in anechoic chambers. The analysis takes into account the influence of the measurement distance, setup of anechoic chamber and other parameters. Furthermore, the work deals with a validation of both types of anechoic chambers and examines the impact of selected parameters on the measurement results. Based on the theoretical analysis and practical measurement, the comparation between semi and fully anechoic chamber, or a three and ten meter measuring distance was made. This thesis also contains a detailed analysis of sources of the uncertainty.
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Electromagnetic field scanner and its utilization in EMC measurement
Chupáč, Michal ; Číž, Radim (referee) ; Kubánek, David (advisor)
Master’s thesis is focused on making the acquaintance of EMC issues and ways of electromagnetic field scanner RS321 utilization for pre-compliance measurements. First part contains analysis of available equipment’s influence on measurement results on the basis of gathered specification. Next part includes an example measurement used as operational manual for scanner and its controlling program. The most important part is correction evaluation for performed EMI measurement of signal generator using its EMC certification protocol and application of gained correction curve on independent EMI measurement of device tested by EMC testing laboratory. Other possibilities of scanner utilization are mentioned in the next chapters. Last part of the thesis contains suitability evaluation of EMC scanner on the basis of findings from performed measurements.
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Virtual Measurement System for the Anechoic Chambers
Váško, Ondřej ; Soldán, Josef (referee) ; Dřínovský, Jiří (advisor)
Master thesis examines a selected part of electromagnetic compatibility. In this work, there is theoretically discussed how electromagnetic interference appears and how is spread through free space environment. To eliminate ambient interference signals, the measurements have been performed in anechoic chamber where the undesirable interference signals were suppressed. In the thesis, there are also described parameters of EMI receivers and limits of electromagnetic interference. The description of calculations of the antenna height for finding maximum intensity of electric field strength for standard measurement distance has been made. For proposed transformed measurement distance, calculations of intensity electric field with addition of parameters measuring antenna and object under test were performed. Correction curves for conversion intensity electric field have been obtained as the result.
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