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Design of a new iontometer with wireless communication and weather station
Kadlček, Václav ; Hrabina, Jan (referee) ; Roubal, Zdeněk (advisor)
This diploma thesis deals with the design of an autonomous system for the measurement of the concentration of atmospheric ions. This is a new version of the already asembled Iontmeter by UTEE FEKT. Unlike the previous version, this new one should be completely independent of electrical network and configurable even without a PC. The design includes increased water and dust resistance, wireless transmission from the weather station and its own temperature, atmospheric pressure and relative humidity sensor.
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The design of rf impedance meter
Wiesner, Jiří ; Hrabina, Jan (referee) ; Roubal, Zdeněk (advisor)
The first part deals with the basic methods for measuring an unknown impedance. After determining the parameters of the desired impedance analyzer method was chosen AC unbalanced Wheatstone bridge. As a source of harmonic signal has been selected direct digital synthesis circuit and measure provides the analog vector voltmeter. Subsequently, it is discussed the issue of determining the sign of the unknown phase impedance. The thesis describes the wiring of circuit AD8302 and circuit AD9958 direct digital synthesis for which it is also an example of the code. It discusses the design and simulation of a reconstruction filter. Finally there are the measured output voltage and spectrum synthesizer.
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Metal detector for industrial use
Stehno, Rostislav ; Hrabina, Jan (referee) ; Szabó, Zoltán (advisor)
The goal of this project is explore and study the ways of metal detecting and create a metal detector for industrial use. When the device were inventing, a lot of methods were studied and the impulse detect method were chosen as the most perspective way of metal detecting, thanks to a huge electronics parts possibilities. After experiences with preceding device was necessary to redesign it. Main target of this thesis is to increase the computing power of detector. For this purpose will device need a new microcontroller. Device will communicate with PC trough a USB port. The device will have a battery which allows device to run for a few hours. Processing of measured data will be make even with DFT which will lead to better analyze of mass and type of conductor under device.
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Digital audio wireless transmission
Juráň, Jeroným ; Hrabina, Jan (referee) ; Szabó, Zoltán (advisor)
This document describes the design of evaluation boards for wireless transmission of audio signal. The boards use WiSA compliant modules. It describes schematics of transmitter board, receiver board and boards of both AD and DA converter. Secondly the document describes the designed PCBs and demonstrates the results by photodocumentation. It also includes description of C library for using FLASH memory to store data and the C driver for FT800 chip and the typical application using this chip including touch
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Smart metering
Lahodný, Libor ; Hrabina, Jan (referee) ; Szabó, Zoltán (advisor)
Semester paper describes the design of smart sockets and their management. Sockets are wirelessly controlled by a central unit. The socket has an integrated sensor, designed to measure current consumption of the device. If necessary, it can remotely disconnect the unit plugged in socket from AC network. Work includes analysis of individual system elements, design of electrical schematics and PCB. In the construction is included ethernet module, which is used to display data using a computer.. The device has been constructed and tested.
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Optical frequency distribution with full compensation of induced phase noise
Pravdová, Lenka ; Čížek, Martin ; Hrabina, Jan
In applications demanding high optical frequency stability, two or more reference stages are usually necessary to ensure the laser source's short-term and long-term stability. The short-term stability can be obtained by locking the laser to a high-finesse optical cavity, while the long-term stability can be formed by, for example, a hydrogen maser referenced by a synchronisation signal from a GPS receiver. During the distribution of stable optical frequencies to the target applications, the transmitted signal is affected by the interfering effects of the surrounding environment. This is especially evident in optical fibre transfers, where acoustic interference, vibrations and environmental temperature changes cause induced phase noise. This work describes the distribution network of stable optical frequencies between individual frequency references within the ISI CAS laboratories. The key parts of the setup are realised by free-space optics, and all of the optical links are fully compensated to induced phase noise effects.
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Frequency references and dissemination
Hrabina, Jan ; Pravdová, Lenka ; Šarbort, Martin ; Čížek, Martin ; Holá, Miroslava ; Oulehla, Jindřich ; Pokorný, Pavel ; Lazar, Josef ; Číp, Ondřej
The work deals with an overview of research topics of the “Frequency references and dissemination” group, Department of Coherence Optics, Institute of Scientific Instruments, Czech Academy of Sciences. These topics include frequency locking of lasers by laser spectroscopy and high-finnese optical cavities, digital holography and optical frequency tranfers through fiber and free-space optical links.
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System of frequency standards at the ISI
Čížek, Martin ; Hrabina, Jan ; Pravdová, Lenka ; Číp, Ondřej
The contribution presents a system of frequency standards developed at the Institute of Scientific Instruments of the Czech Academy of Sciences. It discusses the need for highly coherent optical frequency references for demanding experiments in spectroscopy with cooled atoms. The system comprises interconnected standards operating in the radiofrequency and optical parts of the electromagnetic spectrum, including an active hydrogen maser, a fiber laser locked to a high-finesse optical resonator, and an optical frequency comb. The relative frequency stability of these standards is analyzed, highlighting their suitability for different integration times and applications. The article also describes the experimental setup for comparing the stability of the frequency standards at the Institute of Scientific Instruments with those at the BEV laboratory in Vienna using a stabilized phase-coherent optical fiber link. The results demonstrate the excellent stability of the frequency standards reaching the -15th order of magnitude, essential for spectroscopy and ion trapping experiments.
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