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Frequency synthesizer for microwave communication systems
Klapil, Filip ; Vondra, Vlastimil (referee) ; Kasal, Miroslav (advisor)
The main aim of the thesis is to develop a solution of a frequency synthesizer for a microwave communication systems. Specifically, it suggests a design for frequency synthesizer with phase-locked loop. At beginning of the thesis the principle and basic properties of this method of signal generation are explained. Then it is followed by a brief discussion of the parameters of synthesizers and their influence on design. Another part of the work is the analysis of circuit the frequency synthesizer with the phase-locked loop MAX2871, which is followed by a proposal for the design of the frequency synthesizer module hardware. The last part of the work deals with practical implementation, verification of function and measurement of achieved parameters and their evaluation.
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SMV-2019-58: Development of programmable acquisition system with pulse generator
Vondra, Vlastimil
The contract research project consists of:\n• assessment of the equipment specification in terms of the equipment implementation possibilities using the contractor's instrumentation,\n• analysis of the requirements of the assignment and development of the generator solution methodology,\n• preparation of a proposal for implementation according to the desired characteristics,\n• manufacturing mechanical and electrical parts and purchasing the necessary components,\n• Verification of theoretical initial requirements by practical measurements at a designated location\n• assembling 1 piece of experimental equipment,\n• installation, calibration of equipment at the filling site,\n• Operator training at the client's.\n
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Low Noise Amplifier for the S Band
Benites Ayala, Ivan Alejandro ; Vondra, Vlastimil (referee) ; Kasal, Miroslav (advisor)
This master's thesis presents the design and the realization of a low noise amplifier (LNA) for the S band of radio frequency spectrum from 2.3 GHz to 2.4 GHz. This thesis is mainly focused on stability and impedance matching networks study. Ansoft Designer and ANSYS HFSS programs are used for this design to simulate the LNA. Different low noise devices are simulated in order to find the best results for the final design. Moreover, a coaxial cavity resonator is designed in the input of the LNA and works as a band pass filter. Finally, the LNA is fabricated and its properties compared with the simulation results.
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Hemodynamic modelling in the calf — A pilot study
Matějková, M. ; Jurák, Pavel ; Soukup, L. ; Halámek, Josef ; Viščor, Ivo ; Langer, P. ; Vondra, Vlastimil
With increasing age, the cardiovascular system loses its efficiency. The goal of this work was to investigate the hemodynamic system response to a head-up tilt test in two groups of different aged people. We used a model for describing this response in the right calf based on a non-invasive, non-occlusive, bioimpedance signal measurement technique. A decrease in the bioimpedance value in the calf during the head-up tilt test is associated with the accumulation of blood in the calf, which can be expressed by a model parameter. Subjects were examined in both a head-up tilt test and a supine position. 50 healthy non-smoking volunteers were divided into two groups according to age. The impedance signal during the tilt test for each subject was fitted by a model exponential function: Z0 model EF(t) =A exp(-t/B)+C, where Z0 model EF(t) is the calculated model of electrical impedance in the calf by an exponential function, A is the amplitude of impedance change, B is the time constant of the impedance decrease, C is the value of the steady state after the tilt test and t denotes time. A lower time constant B shows a faster filling of the vascular system in the investigated part. The Mann-Whitney test (p-value<;0.005) revealed that the time constant B for the older group was significantly lower than for the young group (145.24+/- 80.28 vs. 239.23+/-136.59 sec.). A lower time constant value means a faster response to blood filling in the lower limbs and directly reflects decreased vessel elasticity. This time constant was lower in the older group. The results show increased vessel stiffness in old age and could lead to a non-invasive evaluating the cardiovascular system state.
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SMV-2017-29: Current generator for 3D space coil systém GMP4
Vondra, Vlastimil
Development of an advanced experimental system for adjustment of the magnetic field inside the 3D coil system according to defined requirements, including the time programming of the magnitude and direction of the magnetic. field vector. The system is equipped with accurate monitoring of the actual magnitude of mg. field vector that is connected in the feedback loop.
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Solid State Power Amplifier for the L-Band
Pecen, Vojtěch ; Vondra, Vlastimil (referee) ; Kasal, Miroslav (advisor)
The goal of this diploma's thesis is to create a design of a two stages amplifier working in a band reserved for the secondary surveillance radar at the frequency of 1090 MHz. Output power of the amplifier should be 20 W and efficiency should be as high as possible. Because of this the second stage is designed in class C. Contents of this diploma's thesis include a theoretical analysis, simulations of the amplifier parameters, comparison of the Ansys Designer and AWR Microwave Office simulation programs and design of both stages of the amplifier, followed by a comparison of the measured parameters with the simulations.
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Bioimpedance signal processing
Valíčková, Vladimíra ; Vondra, Vlastimil (referee) ; Soukup, Ladislav (advisor)
Theoretical part of this Bachelor thesis deals with properties measurement and use of bioim-pedance signal for medical diagnostics. The practical part deals with detection of important points in derivate bioimpedance signal that may be further used in various medical applicati-ons. This work compares three detection methods. The best results were achieved by a de-tection with fixed interval there were excluded only 1,09 % values. Very similar results had detector dependent on constant bioimpedance. Here was excreted 1.18 % of detections. Algo-rithms that are dependent on length of RR interval perform worse. Furthermore, there is cal-culated the Pulse wave velocity in six parts of the human body in a horizontal and tilt patient position. In the tilt position were the pulse wave velocity about 38.59 % faster than in hori-zontal.
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Processing of a continual blood pressure signal
Svobodová, Ivana ; Soukup, Ladislav (referee) ; Vondra, Vlastimil (advisor)
Bachelor thesis contains a general description of the blood pressure phenomenon and its importance and also deals with diseases, such as hypotension and hypertension. The work also includes a literature review of blood pressure measuring methods. Closely are discussed the non-invasive methods. The result of the work is also a unique program designed in Matlab, which is developed for signal processing of continuous blood pressure measurement for detection of SBP and DBP and MAP, pulse after pulse. To verify the functionality of the program, the further implementation was carried out in GUI. In conclusion, the obtained data are beeing analyzed statistically.
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Processing of heart sounds signals
Němcová, Simona ; Matějková, Magdaléna (referee) ; Vondra, Vlastimil (advisor)
This bachelor thesis is focused on the heart sound signal. It describes the principles of hear sound formation, measurement methods and especially the analysis of the measured phonocardiography signal. In the practical part of this thesis, the algorithm for detecting the first and the second heart sounds is designed by using MATLAB software. Its principle is realized in finding maximum or center of gravity in the filtered phonocardiography signal.
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Thermal comfort and its estimation
Žáková, Monika ; Vondra, Vlastimil (referee) ; Nováková, Zuzana (advisor)
This paper summarizes the problems of human thermoregulation and its measurement, with a focus on the method of indirect calorimetry in resting conditions at different ambient temperatures and during physical activity. It also introduces the issue of human thermal comfort and the methodology of its monitoring using thermal manikin. It describes PowerCube Ergo (Ganshorn, Germany) and Cardiovit AT-104 (Schiller, Switzerland), the diagnostic devices used to spiro-ergometry measurements. It introduces the options to export data. The work proposes the protocol for measuring the thermoregulation of the small group of volunteers, which is realized by the practical part. According to the same protocol is monitored thermal comfort of the thermal manikin. In MATLAB is created the application, allowing clear analysis of measurement records. The data are evaluated and discussed.
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