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Methods for quadrature modulator imbalance compensation
Povalač, Karel ; Valenta, Václav (referee) ; Maršálek, Roman (advisor)
Quadrature modulator (demodulator) is used in transmitting (receiving) part of many devices. Unwanted imbalance can influence amplitude, phase or DC offset of modulator (demodulator). Correction of imbalance was a main subject of thesis. Simulations of these methods were created in MATLAB and results were compared. Basics of methods were implement on programmable logic field by program Xilinx ISE. Development kit V2MB1000 with analogue board Memec P160 was chosen for this purpose. In the last part were compare simulation results with practical measurement.
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Software defined transceiver for radio amateur use
Paus, Anton ; Povalač, Karel (referee) ; Žalud, Václav (referee) ; Šrámek, Petr (advisor)
This project deals with possibilities of using the software defined radio conception for radio amateur use in a short wave band and its subsequent implementation into properly designed hardware. The aim of this work is to design a transceiver that would be capable of working in AM, FM, SSB, and CW modes. Within a theoretical part of the project the architectures of software defined radios and their components are discussed. This part was focused mainly on analog parts of the chain, such as amplifiers, filters and converters. Signal processing algorithms for both receiver and transmitter working in desired modes are studied subsequently and their computer models are built. Designed algorithms are implemented into FPGA structure (Virtex -5).
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Generic logic analyzer
Tajč, Martin ; Povalač, Karel (referee) ; Kubíček, Michal (advisor)
The aim of the project is to design a generic logic analyzer based on an FPGA. The analyzer should be able to analyze protocols such as I2C, SPI, RS232, RS485 and GPIO. The captured data can be observed using an embedded graphical display or using a PC. The PC can be used to control the analyzer and to save the captured data. The thesis is divided into several parts. First, the basic structure of the analyzer is described including detailed description of its particular components. Later on, the most common protocols that can be decoded using the analyzer are described. Finally, the FPGA subsystem and microcontroller application are presented together with corresponding source codes.
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Spectrum sensing and multicarrier systems optimization for cognitive radio
Povalač, Karel ; Šimša, Jan (referee) ; Galajda,, Pavol (referee) ; Maršálek, Roman (advisor)
The doctoral thesis deals with spectrum sensing and subsequent use of the frequency spectrum by multicarrier communication system, which parameters are set on the basis of the optimization technique. Adaptation settings can be made with respect to several requirements as well as state and occupancy of individual communication channels. The system, which is characterized above is often referred as cognitive radio. Equipments operating on cognitive radio principles will be widely used in the near future, because of frequency spectrum limitation. One of the main contributions of the work is the novel usage of the Kolmogorov – Smirnov statistical test as an alternative detection of primary user signal presence. The new fitness function for Particle Swarm Optimization (PSO) has been introduced and the Error Vector Magnitude (EVM) parameter has been used in the adaptive greedy algorithm and PSO optimization. The dissertation thesis also incorporates information about the reliability of the frequency spectrum sensing in the modified greedy algorithm. The proposed methods are verified by the simulations and the frequency domain energy detection is implemented on the development board with FPGA.
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Classification of digital modulation type
Balada, Radek ; Kováč,, Michal (referee) ; Povalač, Karel (advisor)
The aim of master’s thesis is a classification of digital modulation type. The interest in modulation classification has been growing for last years. It has several possible roles in both civilian and military applications such as spectrum sensing, signal confirmation, interference identification, monitoring and so on. Modulation classification is an intermediate step between signal detection and successful demodulation. Therefore the known methods are based on different statistics obtained from received signals. These statistics can be derived from continuous time signals and they hold for sampled signals.
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Detection of radio communication signal in frequency domain
Zátyik, Ján ; Povalač, Karel (referee) ; Maršálek, Roman (advisor)
The purpose of my bachelor’s thesis is to describe different methods of detection of radio communication signal in frequency domain. Describes principle of methods Bartlett, Welch, Multitaper, Yule-Walker and Burg for power spectrum estimation of signal. Compares simulation of methods based on described theory with methods of the software MATLAB. Firstly, performs simulation for noiseless signals OFDM, 8PSK, CDMA and finds out their usability for these signals. Secondly, repeats simulations with the same configuration of methods for noisy signals and finds out their usability for real signals.
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Miniature PC monitor realization
Nečesaný, Jaroslav ; Povalač, Karel (referee) ; Frýza, Tomáš (advisor)
Objective of the Master Thesis was to bring in two solutions of miniature PC display. One of them uses the VGA signal as the source of the data. The second uses USB for communication. Display using USB was chosen to be produced. Device contains LCD screen, SD card reader and audio DAC with mini speaker. Software running on the PC allows user to watch part of the screen of the computer. Position and size of the chosen part may be varied. The display may be controlled by touch screen. One part of the software running on PC is a simple video player.
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