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Laboratory High-Frequency Generator
Konzal, Jan ; Záplata, Filip (referee) ; Šebesta, Jiří (advisor)
This thesis describes a proposal of laboratory high frequency generator based on the principle of indirect analogue synthesis with a phase sling. The first part of the work describes the principle of a direct numerical and indirect analogue synthesis. Frequency range of the designed generator is up to 900 MHz. The output of the generator is designed to be up to 12dBm. Output impedance is 50 . To reach a frequency of oscillation lower than 800 MHz, the principle of fusion is used. Further, the control was suggested to be carried out by a microprocessor. Operating is realized using a keyboard and a rotary encoder.
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Concept of three-phase active rectifier
Bareš, Jiří ; Pazdera, Ivo (referee) ; Huták, Petr (advisor)
This work deals with three-phase active rectifier control. In first, theoretical part it describes several control strategies with focus on voltage oriented control. For this type of control a design is worked out, and created model and its simulation is described. Second, practical part deals with realisation on microcontroller TMS320F28335, which is main processing unit of device lent by company Elcom. Therefore in this part abilities and settings of the controller along with developped control algorithm are described. Reached results of measurement are then presented and in the conclusion they are evaluated.
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Power source for pulse magnetron sputtering
Schulz, Jakub ; Magát, Martin (referee) ; Šteffan, Pavel (advisor)
The presented thesis deals with the design and assembly of the generator for pulse magnetron sputtering. The designed device is capable of generating two square wave signals via its counter-working outputs. Both signals have independently adjustable frequency, pulse count and duty ratio. Both signals originate from two frequency syntheses controlled by microcontroller PIC16F877A. All the settings are entered by four buttons and are shown on an alphanumeric display with 16x4 characters. The duty ratio is adjusted using a special module.
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Laboratory Model of the Vortex Speed Indicator
Kazda, Ondřej ; Kolka, Zdeněk (referee) ; Biolková, Viera (advisor)
This work is concerned with posibility of measuring a wind flow by Von Karman vortex sheed structure. The bluff body is situated in the way of air flow propagation and consequentally vortexes will be appeared. Important part of speedmeter design is measurment chamber must allow to vortex sheed propagation. The transient and the reciever are situated vertically to propagation of flow.The Ultrasonic carrier is transmitted and modulated by freqency of vortex sheeding in measurment chamber.Demodulator uses PLL to “focusing“ detection of the ultrasonic beam. This can be indicated like lock and unlock phase loop. From known value of sheed frequency can be directly calculated speed of flow.
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Spectrum Analyzer up to 500 MHz
Čada, David ; Vimperk), Tomáš Baráth (Rohde Schwarz (referee) ; Šebesta, Jiří (advisor)
This project deals with design and realization of the spectrum analyser using double superheterodyne topology with frequency range up to 500MHz. This work solves hardware blocks like phase lock loops, intermediate frequency filters, saw filter, crystal filter, logarithmic detector. Content of work is also design description and tuning of spectrum analyzer parts.
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Design of magnetic bar-code read head
Kadlčík, Libor ; Drexler, Petr (referee) ; Mikulka, Jan (advisor)
Magnetic bar-code is composed from ferromagnetic bars printed on a substrate. The amount of ferromagnetic material is low, therefore reading magnetic barcode requires sensitive methods. Principle of methods of sensing both low-intensity magnetic field (fluxgates) and detecting low concentration of ferromagnetic material (resonant circuit, differential sensor) will be described. There are sensors producing frequency-modulated signal, therefore we focus on frequency demodulators as well. Signal acquired by sensor suffers from convolution distortion, reconstruction methods will be introduced. The assembled device consists of sensing oscillator, frequency demodulator, amplifier and reconstructing circuit. Frequency demodulation is done by phase-locked loop or differential demodulator. Reconstruction is based on detection of inflection points, producing square signal (representing bars of barcode). Design of these blocks is described. The device is able to read magnetic barcodes and reconstruct convolutionary distorted acquired signal. The differential demodulator exhibits low noise and low temperature drift (contrary to phase-locked loop). Signal produced by reading 2 mm wide bars is reconstructed without any problems, bars of width less than 1 mm cause troubles in certain cases (due to high degree of convolution distortion).
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Control Unit for VHF Radio Receiver with Frequency Synthesizer
Sobotka, Martin ; Šebesta, Jiří (referee) ; Vyskočil, Pavel (advisor)
The aim of this work is to propose the involvement of the control unit for receiving VHF radio and its practical implementation. Adding a panel on the appropriate tuner unit leads to a complete receiver to receive radio broadcasts. My work is to focus on two frequency bands: VHF band for broadcasting and VHF band for air radio communication. This paper describes a process of selection of component, their description and integration into a complete circuit, a description of the control program for the microcontroller and a description of control device. Scheme and the draft for the manufacture of printed circuit board is attached.
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Laser with Narrow Spectral Linewidth for Metrology of Length
Pham, Minh Tuan ; Smrž, Martin (referee) ; Peterka,, Pavel (referee) ; Číp, Ondřej (advisor)
Práce se zabývá stabilizací diodového laseru pracujícího na vlnové délce 729 nm, který slouží pro přesnou spektroskopii a interakci se zachycenými a chlazenými ionty vápníku. Interakce s iontem vyžaduje, aby excitační laser měl extrémně úzkou šířku spektrální čáry. V práci jsou vysvětleny důležité postupy a metody vedoucí k dosažení provozu laseru se spektrální šířkou čáry v řádu Hz či nižší. Součástí práce je sestavení optické sestavy pro tento laser a k ní potřebných elektro-optických prvků. Hlavní důraz je kladen na techniky stabilizace laserové frekvence pomocí externích referencí, jejich teoretický popis a implementace je rovněž součástí této práce. Jako první přístup o zúžení spektrální čáry je zvolena metoda uzamknutí optické frekvence laseru na vybranou komponentu hřebene optických frekvencí pomocí elektronických fázových závěsů. Měření spektrálního šumu bylo provedeno pomocí dvousvazkového interferometru s nevyváženými rameny. Dosažené výsledky potlačení šumu u takto uzamčeného laseru byly poté porovnány s režimem laseru volně běžícího. Dalším postupem je uzamčení spektrální čáry laseru na velmi úzkou čáru vysoce jakostního optického rezonátoru. Touto metodou jsem dosáhl laseru s velmi úzkou spektrální čáru (v řádech desítek Hz), avšak s krátkodobou stabilitou. Finálním krokem bylo pak sestavení a použití techniky "trasfer oscillator", která zajistila dodatečnou kompenzaci nežádoucího driftu rezonančního modu optického rezonátoru a tímž zajistila dlouhodobou stabilitou celého systému. Takto stabilizovaný laser na 729 nm byl testován ve spektroskopii na zakázaném přechodu opplerovsky zchlazeného iontu vápníku.
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Wideband 6GHz RF Signal Generator
Mička, Josef ; Kubíček, Michal (referee) ; Urbanec, Tomáš (advisor)
The goal of this thesis is a design of a wideband high frequency generator with an adjustable output amplitude. The generator is based on a frequency synthesizer ADF4355. The power level of an output signal is adjustable by an attenuator HMC1119. The created generator is accesisible trough an user-friendly control panel or by SCPI commands. Frequency synthesis can run in an integer mode or a fractional mode. The output signal has a very low phase noise when it is running in the integer mode.
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