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VHF/UHF Front-End for Software Receiver
Losenický, Roman ; Vágner, Petr (referee) ; Šebesta, Jiří (advisor)
The first part of this work contains the detailed analysis of the basic VHF and UHF receiver characteristics. The most important parameters, like Noise figure, selection or gain, are qualified shortly. The following chapter analyzes above-mentioned parameters and shows some calculations and analysis to design a receiver. In the third part the receiver design is proceed. It specifies a basic block diagram. The base of design is formed by a mixer SRA-1+, which choice is not part of this project. Design of preselectors is the main goal of the project. They use BF998 FET transistors and band pass filters determining three frequency bands: 140-145 MHz, 220-230 MHz and 420-430 MHz. Filtered signals go on into the channel selector afterwards. The user can determine , which one of the three input signals will be routed to the mixer, using a switching diode HSMP3823. Each part, including preselector amplifier and filters, is placed into the separated tinned boxes. These boxes are linked with the switching circuit by the coaxial line.
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Low noise 70 cm band amplifier
Klügl, Jan ; Vágner, Petr (referee) ; Urbanec, Tomáš (advisor)
This master's thesis is engage in suggestion of low noise 70 cm band amplifier with filter and diode attenuator. At first the thesis describes the basic parameters of amplifier, for example gain, noise figure and dynamic extent. Later in detail describes individual parts, which are the device consist of. At every part of system is mentioned the diagram of connection and values of components, which are ascertained from calculation, simulation and recommendation of producer. The characteristic parameters of amplifier were measured after construction.
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Precise Frequency Generator - DDS
Kratochvíl, Petr ; Vágner, Petr (referee) ; Baran, Ondřej (advisor)
This work deals with frequency generators based on the direct digital synthesis method DDS. Basic principles and attributes of the frequency generator DDS are explained. The text describes parameters influencing and defining a quality of the generated signal. The list of available integrated circuits realizing the direct digital synthesis is mentioned. A construction of the DDS generator with a device AD9954 and the generator control are described. At the end of the work, the function and parameters of the designed generator are verified.
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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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Doble-balanced mixer - laboratory equipment
Dušek, Libor ; Baran, Ondřej (referee) ; Vágner, Petr (advisor)
The aim of this work was double-balanced mixer implementation, which will be used like laboratory equipment. This thesis deals with design of the double-balanced mixer from first theoretical principles to a practical design of a laboratory equipment. For the practical design the integrated mixer SA612 was used. Input signal to the mixer up to 500 MHz frequency can be used. For required operation external oscillator and fifth-order low pass filter were constructed. Oscillator was designed for fixed frequency 32 MHz. Fifth-order low pass filter was inserted between the mixer and the oscillator, because of filtering higher harmonics. The second aim of the work was measuring double-balanced mixer basic parameters, such as Compression Point (P-1dB) and Intercept Point (IP3). For the IP3 measurement, another one device was required. It consists of the power combiner for mixing two frequency close signals and third-order bandpass filter, which selects required frequency band. Finally, the laboratory equipment was fabricated and its real parameters were measured.
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Low-noise S-band amplifier
Potěšil, Dušan ; Vágner, Petr (referee) ; Kasal, Miroslav (advisor)
This work deals with design, simulation and realisation of a receiving systém of an S-band front end for satellite communication. The first part of the project is designed the low noise amplifier (LNA) with high associated gain. The basic point of the design is choice of the active device. In the present time are available the ultra low noise transistors based on the GaAs with high mobility electron. The two-stage LNA has been designed with Agilent ATF-55143. It is pseudomorphic HEMTs ,which work in an enhancement mode.These transistor do not require a negative bias voltage and have extremely good typical noise figure. The design includes an interdigital tuned band pass filter between stages. The second part of the project is search another way design circuit. There are designed two LNA with paralel coupled line filter. The first has been applied on a PTFE substrate Duroid 5880 with relative permitivity 2,2 and tg d = 0,009. The substrate FR-4 (r = 4.34) with the thickness 0.06” was used for the realization.
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Thermoregulator of piezoelectric crystal unit
Roubal, Zdeněk ; Vágner, Petr (referee) ; Kasal, Miroslav (advisor)
This thesis deals with thermal stabilization of crystal oscillators. A simple thermostat of piezoelectric crystal unit is designed in first part. Main emphasis is set to low input power. The second part deals with crystal oscillators with 102,5MHz and 10MHz frequency. They are simulated with Ansoft Designer software. Both of these oscilators are measured for short term and midterm frequency stability.
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Low-noise amplifier for 145 MHz band
Pivoňka, Rostislav ; Vágner, Petr (referee) ; Baran, Ondřej (advisor)
This work contains a description of low noise amplifier (LNA) working on 145 MHz. This amplifier consists of three parts. They are input circuit, active device and output circuit. The amplifier is designed with transistor BF 998 on substrate FR4. The design and simulations are performed by means of software Ansoft Serenade. The design was completed with the help of design equations and Smith chart methods. The input of amplifier is noisy matched and output of amplifier is matched on impedance 50 ohms. The noise factor in frequency band 144 – 146 MHz is about 0,85 dB. The amplifier gain is in this band circa 16dB.
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Tuner for UHF Receiver with Low Power Consuption
Kaštánek, Martin ; Vágner, Petr (referee) ; Urbanec, Tomáš (advisor)
The purpose of this work was to make a proposal for input parts of receiver for band 430 to 440 MHz. A model of chosen semiconductor triode BFP540 was created in simulation software. Possibilities how to decrease consumption of this semiconductor triode, keeping the profit, were investigated through the simulation.In compromise consumption, keeping the profit of the amplifier - an optimal operating point for this semiconductor triode UCE = 1,2 V and IC = 2 mA was found. It was tested through the testing wiring with noise microstrips conformity. Ascertained knowledge was used for construction of tuner for UHF receiver. An operating point of input amplifier of UHF receiver was owing to power supply amplifier forced for bigger effectiveness to UCE = 2,65 V and IC = 2,0 mA. Suppression of mirror frequency is provided with Helix filter of the third order, because of intermediate frequency 10,7 MHz. Mixing on intermediate frequency is made again by semiconductor triode BFP540. Selectivity of receiver is provided with intermediate frequency crystal filter 10,7 MHz with bandwidth 15 kHz. Designed input part enables reception of SSB, FM and digital types of modulation.Bandwidth intermediate frequency exit is adapted to this request To receive particular modulation , it is necessary to complete intermediate frequency signal way with appropriate intermediate frequency filter.
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Influence of traffic accessibility with unemployment rate in the Region of Český Krumlov
Vágner, Petr ; Květoň, Viktor (advisor) ; Pova, Patrik (referee)
Traffic accessibility is used to be mentioned in connection with regional development and economy. In my bachelor thesis, I analyse and bring out relationships between unemployment rate and traffic accessibility in the Region of Český Krumlov. I open with characterizing traffic accessibility and its influence on regional development, with a view to unemployment, and I mention theoretical approaches associated with this topic. Later on, I describe statistical and geographical methods used in the practical part of my thesis to bring out relations between the unemployment rate in particular municipality and the accessibility of centers of working microregions. Based on the analysis results, I evaluate hypothesis of higher unemployment in municipalities with low accessibility by public transport and supposed influence of increasing distance and municipalities traffic location.
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