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Wireless transmission interference modeling (AWGN, Rayleigh, Rice fading channels)
Hloušek, Tomáš ; Gleissner, Filip (referee) ; Mikulka, Jan (advisor)
This thesis describes and models wirelesss transmission intereferences in real communication channels. A signal received on a fading channel is subjected to a multiplicative distortion and to the usual additive noise. Real channel adds to the signal noise and fadings. Gaussian noise is a result of channel awgn. Fadings is implicated by multipath propagation of signal in Rayleigh and Rician channels. Main goal of this project is to program BERsolve, which is created in tool GUIDE in Matlab. User program BERsolve makes it possible to analyse bit error rate and symbol error rate for some types of channel models, which are defined by standard COST207. BERsolve offers some other functions i.e. display time behaviour, constellation diagram and spectrum. This program provides us with an overview representation of problem by multipath interferences in communication channels.
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Implementation of restoring method for reading bar code
Kadlčík, Libor ; Bartušek, Karel (referee) ; Mikulka, Jan (advisor)
Bar code stores information in the form of series of bars and gaps with various widths, and therefore can be considered as an example of bilevel (square) signal. Magnetic bar codes are created by applying slightly ferromagnetic material to a substrate. Sensing is done by reading oscillator, whose frequency is modulated by presence of the mentioned ferromagnetic material. Signal from the oscillator is then subjected to frequency demodulation. Due to temperature drift of the reading oscillator, the demodulated signal is accompanied by DC drift. Method for removal of the drift is introduced. Also, drift-insensitive detection of presence of a bar code is described. Reading bar codes is complicated by convolutional distortion, which is result of spatially dispersed sensitivity of the sensor. Effect of the convolutional distortion is analogous to low-pass filtering, causing edges to be smoothed and overlapped, and making their detection difficult. Characteristics of convolutional distortion can be summarized into point-spread function (PSF). In case of magnetic bar codes, the shape of the PSF can be known in advance, but not its width of DC transfer. Methods for estimation of these parameters are discussed. The signal needs to be reconstructed (into original bilevel form) before decoding can take place. Variational methods provide effective way. Their core idea is to reformulate reconstruction as an optimization problem of functional minimization. The functional can be extended by other functionals (regularizations) in order to considerably improve results of reconstruction. Principle of variational methods will be shown, including examples of use of various regularizations. All algorithm and methods (including frequency demodulation of signal from reading oscillator) are digital. They are implemented as a program for a microcontroller from the PIC32 family, which offers high computing power, so that even blind deconvolution (when the real PSF also needs to be found) can be finished in a few seconds. The microcontroller is part of magnetic bar code reader, whose hardware allows the read information to be transferred to personal computer via the PS/2 interface or USB (by emulating key presses on virtual keyboard), or shown on display.
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Ultrasonic Directional Speaker
Sedlák, Jiří ; Michalec, Jaroslav (referee) ; Mikulka, Jan (advisor)
The master´s thesis deals with theoretical research and practical application of the principle of spreading acoustic waves through nonlinear medium. The theoretical part describes five different types of amplitude modulation and their mathematic representation, which were verified by the program Matlab. Next, the impedance characteristic of ultrasound PZT transducer was measured and the design of PWM modulator and class D amplifier was described. The practical part of the master´s thesis contains the realization of the parametric loudspeaker assembled from the class D amplifier and the PWM modulator. In conclusion, the designed parametric loudspeaker was measured and the individual types of amplitude modulation were compared with respect to the total harmonic distortion of transmitted useful signal.
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A System for Eye Movement Tracking
Urbanová, Lucie ; Marcoň, Petr (referee) ; Mikulka, Jan (advisor)
V této bakalářské práci jsou diskutovány možnosti a aplikace systému pro sledování pohybu očí, obsahující i aktuálně na trhu používané produkty. Práce následně uvádí řešení takového systému. Obsahuje návrh a realizaci držáku pro pevné uchycení kamery. Práce obsahuje i realizaci softvéru vytvořeného v C/C++ za využití Visual Studia a knihoven OpenCV. Tato aplikace sestává z procesů detekce očí, testování a vyhodnocení. Jako součást práce je provedeno a vyhodnoceno testování vytvořeného systému. Práce rovněž posuzuje vlastnosti systému a nabízí připadná rozšíření.
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Segmentation Methods in Biomedical Image Processing
Mikulka, Jan ; Přibil, Jiří (referee) ; Dostál, Otto (referee) ; Gescheidtová, Eva (advisor)
The PhD thesis deals with modern methods of image processing, especially image segmentation, classification and evaluation of parameters. It is focused primarily on processing medical images of soft tissues obtained by magnetic resonance tomography (MR) and microscopic images of tissues. It is easy to describe edges of the sought objects using of segmented images. The edges found can be useful for further processing of monitored object such as calculating the perimeter, surface and volume evaluation or even three-dimensional shape reconstruction. The proposed solutions can be used for the classification of healthy/unhealthy tissues in MR or other imaging. Application examples of the proposed segmentation methods are shown in this thesis. Research in the area of image segmentation is focused on methods based on solving partial differential equations. This is a modern method for image processing, often called the active contour method. It is of great advantage in the segmentation of real images degraded by noise with fuzzy edges and transitions between objects. The results of the thesis are methods proposed for automatic image segmentation and classification.
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Implementation narrowly directed beeper
Hladký, David ; Drexler, Petr (referee) ; Mikulka, Jan (advisor)
The present final thesis discusses the transmission of a narrowly directional parametric sound beam through an amplitude-modulated ultrasonic wave, utilizing the effect of auto-demodulation in a nonlinear medium and ensuring the subsequent processing of the input signal for the parametric sound transmitter. Emphasis is placed on the mathematical tools that relate to parametric sound transmission in a nonlinear medium. The basic part of the thesis describes a parametric speaker and the associated amplitude modulation techniques, which constitute a major prerequisite for the processing of the transmitted signal. In the following section, the author then analyzes the computational intensity of these techniques, considering applicable hardware approaches. Finally, the fabrication and practical use of the proposed solution are discussed, including the measurement of typical parameters such as the spatial radiation characteristics, total harmonic distortion, and transmission channel bandwidth.
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Estimation of instantanenous frequency
Mik, Šimon ; Mikulka, Jan (referee) ; Kubásek, Radek (advisor)
This bachelor’s thesis describes different instantaneous frequency estimators. Various methods are implement into Matlab software and there are introduced conclusions of testing. Methods are compared in two aspects. The first aspect is accuracy of method which depend on time progress input signal. The second aspect is accuracy of method which depend on ratio frequency of input signal and sampling frequency. Outcomes of tests are compared. The result of this work is evaluate properties each method.
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A laboratory task to verify the properties of audio devices
Staňková, Karolína ; Marcoň, Petr (referee) ; Mikulka, Jan (advisor)
The aim of this thesis is familiarization with the parameters of an audio device and their measurements according to the standards (AES17-2018 and ČSN EN 60268-3). A laboratory task for the Measurement in Audio Engineering course is designed, based on the study of the standards. The first part of the thesis deals with detailed analysis of the measurements of different parameters of audio device. The described procedures are consequently employed to design the laboratory task. The second part of this thesis is dedicated to design the laboratory task. The automatized system based on HP VEE platform was developed to provide the multiple measurement. The attachments of this thesis contain the student’s manual for the laboratory task, the sample protocol, the testing measurement manual and the sample protocol for the testing measurement.
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Perfusion image processing
Dolníček, Petr ; Dvořák, Pavel (referee) ; Mikulka, Jan (advisor)
The goal of this diploma thesis was to create a script in MATLAB, which is capable to load DICOM pictures, read the data in their headers and then select the right series for perfusion analysis. This analysis is based on detection of contrast fluid in bloodstream and tissue and right interpretation of concentration changes of this fluid in time. This work is trying to describe a way of building an ultimate system capable of autonomous tumor analysis and classification. In the end, there is an analysis of DICOM sample performed by created script.
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Portable digitally controlled stabilized source of symmetrical voltage
Hynek, David ; Drexler, Petr (referee) ; Mikulka, Jan (advisor)
This thesis deals with a design of a power supply for a measuring equipment for a geophysical mapping intended to do a reconstruction of an electrical impedance of a ground environment of water reservoirs. The power source is going to be used for laboratory measurements and for outdoor experiments. The thesis describes the selection of suitable components, equipment design and testing. The theoretical part explains the functions of used components and the principle of an electrical impedance tomography. The conclusion summarizes the properties of the proposed solution and evaluates the final product.
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