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Shortwave power amplifier
Fiala, Roman ; Vařacha, František (referee) ; Prokeš, Aleš (advisor)
This master’s thesis describes RF power amplifier design. The designed amplifier has been built. The first three chapters outline basics about radio frequency amplifiers. The basic theory needed for amplifier implementation is also described there. In the fourth chapter the power amplifier is designed. The design is based on the theoretical knowledge. Complete amplifier contains RF preamplifier, power amplifier and filters. The OrCAD PSpice, Ansoft Designer SV and EAGLE programs have been used for the design and verification of some sections of circuits. Measurement results of the built amplifier are in the fifth chapter. This thesis contains also the draft for laboratory exercise.
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Design and construction of audio power amplifier
Růžička, Jaroslav ; Kratochvíl, Tomáš (referee) ; Brančík, Lubomír (advisor)
This bachelor’s thesis is concerned with amplifier classes, integration end-level, protective circuits and concrete concept of class AB power amplifier, including concept of preamplifier and power amplifier. Features of designed circuits were simulated in PSpice software. These individual concepts of modules are connected with DPS. This thesis contains results of measurement and photos of amplifier.
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Parameters of Communication Systems Based on OFDM-CDMA
Blumenstein, Jiří ; Kocur,, Dušan (referee) ; Baudoin, Genevieve (referee) ; Fedra, Zbyněk (advisor)
Cíl disertační práce leží v oblasti modelování a vyhodnocení bezdrátových komunikačních systémů s dvojrozměrným rozprostíráním signálu a jejich klíčových parametrů v závislosti na vybraných vlastnostech moderního bezdrátového komunikačního řetězce. Výzkumné metody použité v této práci spočívají především ve vývoji softwarového simulátoru pro prostředí Matlab, s jehož pomocí, a s využitím statistického přístupu, jsou navržené algoritmy ověřeny. Dále je použit simulátor fyzické vrstvy dle 3rd Generation Partnership Project Long Term Evolution (3GPP LTE), vyvinutý na Technické univerzitě ve Vídni. Tento představuje ideální platformu pro implementaci metody dvojrozměrného (2D) rozprostírání a její vyhodnocení s přihlédnutím k současným bezdrátovým komunikačním systémům. Zjištění prezentovaná v této práci představují především ověření účinnosti systému nazvaného jako Variable Spreading Factor - Orthogonal Code Frequency Division Multiplex (VSF-OFCDM), který využívá principu 2D rozprostírání signálu a zjištění, že VSF-OFCDM systém překonává systémy využívající Orthogonal Division Frequency Multiplex (OFDM), nebo Code Division Multiple Access (CDMA). Dále byla navržena metoda 2D rozprostírání signálu v systému LTE, kde se též potvrdila její účinnost. Díky účinnějšímu potlačení vlivu rychlé variace přenosového kanálu v závislosti na frekvenci a čase, dosahuje systém VSF-OFCDM znatelně vyšší datové prostupnosti.
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Voltage amplifier for Electrical field generation
Nedbal, Jan ; Szabó, Zoltán (referee) ; Kubásek, Radek (advisor)
This bachelor’s thesis is about design and practical realization of the voltage amplifier for generating an electric field defined trace. First part is introduced design of function generator and a DC power supply symmetric. In the second part is the design and simulation of power amplifier in class A and high voltage DC source. The last part is consists of measurements on a function generator, power amplifier and high voltage DC source.
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Class D audio power amplifier
Kaláb, Lukáš ; Petržela, Jiří (referee) ; Kratochvíl, Tomáš (advisor)
This project aims on completed design and consequential realization of prototype of the class D audio power amplifier. Amplifier works for home listening and should power at 2 x 50 W. The machine contains finall degree, correcting pre-amplifier and power supply. The basis for realization of the design (connection diagram, design of printed connections boards, distribution and list of parts) are made in Eagle software. Mechanic configuration of all parts in the body of the amplifier is also part of the work.
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Seqence circuit for radioamateur transciever
Dvořák, Pavel ; Šnajdr, Václav (referee) ; Lukeš, Zbyněk (advisor)
In this paper we will deal involving short-wave radio station and its control by the sequencer. Mostly it will be a time delay of the PA and the antenna switching relay in the transmitter (TX) to receiver (RX) side. Time delays will be controlled programmatically using ATmega 16 microprocessor, which will form part of the main control sequencer. The delay will set the total time of keying in messages, when we take into account the loss due to delayed first symbol. Keying will be done from several sources, among the main sources will be ordered from keying the radio, telegraph keys, and PC. The transmission signal is used amplitude modulation (SSB) in the CB zone.
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Design and Implementation of Active Loudspeaker System with Digital Input
Uchytil, Filip ; Balík, Miroslav (referee) ; Schimmel, Jiří (advisor)
The work is focused on a design of an active loudspeaker system with a bi-amp amplifier and a digital input. There is described the theory of a loudspeaker enclosure design and its practical implementation. Furthermore the work deals with a design and construction of input circuits such as a preamplifier, Baxandall tone control, active crossover, all-pass filter and S/PDIF. On the basis of the amplifier´s theory the optimal construction of amplifiers and their design are selected. The complex design of the loudspeaker box is devised so that it would reach a maximum acoustic power during the preservation of a low distortion.
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Class D audio amplifier for active loudspeakers
Cupák, Jan ; Punčochář, Josef (referee) ; Kratochvíl, Tomáš (advisor)
This master's thesis deals with design of D class audio final amplifier, which was output power 400 W for 4 ? load impedance. Designed audio amplifier is specifical for active speaker, which consists of satelite speakers and subwoofer. Further more it deals also with other functional blocks, e.g. balanced input preamplifier, active crossover and protection for safety running. Outcome of this work are schemes of each functional blocks of D class audio amplifier, whose functionality was verified by simulation. Thesis also contains full reference material including mechanical arrangement of functional blocks on printed connection board. The conclusion contains the measured parameters of function blocks of produced prototype and complete photographic documentation.
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HF and IF circuits of shortwave radiostation
Šnajdr, Václav ; Vágner, Petr (referee) ; Lukeš, Zbyněk (advisor)
The study, description, design and implementation of selected blocks of multiband shortwave radio station are dealt with in the thesis. Focus is placed on the concept of multiband shortwave radio stations, with an emphasis on high frequency and intermediate frequency circuits. The first chapter is devoted to description of the transceiver block diagram which is designed as superheterodyne. The design of bandpass input filters, intermediate frequency crystal filters and output filters is described. Simulation results and the measured characteristics of the implemented functional blocks are presented. Furthermore, the amplifier circuits which maintain impedance matching of individual blocks are discussed. SSB signal generation in the transmitter part of radio station and final stage power amplification are depicted.
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High Efficiency Microwave Power Amplifiers - Laboratory Experiment
Gajzler, Jakub ; Svačina, Jiří (referee) ; Urbanec, Tomáš (advisor)
This Diploma thesis deals with methods that increase efficiency of transistor amplifiers. In the first part of the thesis we describe theoretical background of the constructions of power amplifiers. At first we deal with the classical method that is concerned with a change of position of the static operating point. Secondly we cover the multi harmonic manipulation method (MHM). This method is concerned with a proper loading of particular harmonic components and consequential shaping of voltage runs and currents on the collector. In the second part of the work we have constructed the substitutes of particular accesses. Constructed classes are AB, F and FMHM. Basic S parameters and output signal spectrum were measured. We can see from the calculated efficiencies AB = 11%, F = 16% a Fmhm = 18%, big increase of efficiency F and FMHM only by changing output network.
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