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Studies of Influences of Oscillators Frequency Instabilities in Satellite Communication Systems
Baran, Ondřej ; Baláž, Igor (referee) ; Šimša, Jan (referee) ; Kasal, Miroslav (advisor)
The dissertation thesis deals with a study of an influence of a simultaneous incidence of an additive thermal noise and a multiplicative phase noise on the useful signal transmission in narrowband satellite communication systems. While the additive thermal noise affects the useful signal only on the receiver side of the communication system, the multiplicative phase noise is produced in all system oscillators. One investigates how the receiver filter bandwidth reduction takes effect on the influence of individual noise types. The thesis is divided into four units. The first one (chapters 4 and 5) solves the ways of modeling of both noise types. In the second part (chapter 6), on the simple example, the primary analysis of the phase noise influence is made. Basic modulation schemes used in the satellite communication are also discussed (chapter 7). Third part (chapter 8) is devoted to the modeling of a general digital system with a M PSK modulation made directly on the main carrier wave. The last part (chapter 9) describes the modeling of a digital system with a BPSK modulation on the auxiliary subcarrier wave followed by an SSB modulation on the main carrier wave. General conclusions are deduced from obtained simulation results.
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Adjustable switching power supply
Vyroubal, Rostislav ; Urbanec, Tomáš (referee) ; Baran, Ondřej (advisor)
The aim of this bachelor’s thesis is to create a summary of the convertors, their principles, and to propose the convertor with specific parameters. The printed circuit board is designed for this convertor. Designed convertor is manufactured. Its specific parameters are measured and compared with theoretical parameters. A heatsink is designed for this convertor.
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Antennas Controller in Azimuth and Elevation
Mílek, Čestmír ; Baran, Ondřej (referee) ; Kasal, Miroslav (advisor)
The aim of this semester project is the construction of device which drives an antenna system whose movement is realized by YAESU or EGIS antenna rotors. This antenna controller provides driving on basis data received from PC connected through the USB or autonomous by including required direction or by choosing target satellite from a list in microcontroller. For autonomous function device contains alphanumeric LCD display and four basic buttons. Also it contains PS/2 interface for connecting a numeric keyboard. Rotors driving are realized by two separate driving interfaces for YAESU and RS-232 controlled drivers. Communication with PC is provided by the USB.
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VSAT Terminal Model
Kudlička, Miroslav ; Ondráš, Radek (referee) ; Baran, Ondřej (advisor)
This work deals with the description of the communication using the VSAT satellite network. A used network topology, frequency bands, satellite orbits and also an access technology are defined. The next part is focused on the VSAT terminal, where the block diagram is shown. A model of the indoor unit IDU is designed in the system background of Ansoft Designer. Individual parts of the system model are analyzed in terms of input variables. The results of the simulation are shown. The curves of BER before Viterbi decoding and after Viterbi decoding are shown too.
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Linear Transponder Model
Pospíšil, Miroslav ; Ondráš, Radek (referee) ; Baran, Ondřej (advisor)
This master’s thesis deals with satellite transponders. Firstly, satellite communication basics, satellite services definitions, frequency bands and satellite orbits are investigated. The second chapter forms the satellite transponders analysis. The transparent transponder and the transponder with on-board processing are described. Finally, a transponder model is designed and simulated in communication chain.
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FM Coincidence Detector - Laboratory Equipment
Mlčoch, Jiří ; Urbanec, Tomáš (referee) ; Baran, Ondřej (advisor)
This work is aimed at an analysis of frequency demodulation, design, simulation, and construction of a coincidence demodulator. Chapter 1 explains the basic characteristics of frequency modulated (FM) signals and provides an overview of the required signal bandwidth, the signal spectrum, and the signal-to-noise ratio after demodulation. Chapter 2 describes each type of FM demodulator separately, and it includes all significant types of demodulator for FM radio broadcast. The function of the coincidence demodulator and its characteristics are explained in detail. Chapter 3 contains a theoretical solution of the phase shift network. Calculated values of the circuit elements are verified by simulation with a view to the total harmonic distortion of the demodulator output signal. Chapter 4 describes the front-end circuit of the receiver. Here, the filter design and the mixer circuit description are provided. The final part of the thesis presents the applicable laboratory task.
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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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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 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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