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Wavelet Based Filtering of Electrocardiograms
Smital, Lukáš ; Smékal, Zdeněk (referee) ; Halámek, Josef (referee) ; Kozumplík, Jiří (advisor)
This dissertation deals with possibilities of using wavelet transforms for elimination of broadband muscle noise in ECG signals. In this work, the characteristics of ECG signals and particularly the most frequently occurring type of interference are discussed firstly. The theory of wavelet transforms is also introduced and followed by design of the simple wavelet filter and the more sophisticated version with wiener filtering of wavelet coefficients. Next part is devoted to the design of our filter, which is based on wavelet wiener filtering and is complemented by algorithms that ensure full adaptability of its parameters when the properties of the input signal are changing. Suitable parameters of the proposed system are searched automatically and the algorithm is tested on the complete standard electrocardiograms database CSE, where it achieves significantly better results than other published methods.
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Estimation of accuracy of speech technologies based on signal quality and audio content richness
Nezval, Jiří ; Smital, Lukáš (referee) ; Schwarz, Petr (advisor)
This thesis discusses theoretical analysis of the origin of speech, introduces applications of speech technologies and explains the contemporary approach to phonetical transcription of speech recordings. Furthermore, it describes the metrics of audio recordings quality assessment, which is split into two discrete classes. The first one groups signal quality metrics, while the other one groups content richness metrics. The first goal of the practical section is to create a statistical model for accuracy prediction of machine transcription of speech recordings based on a measurement of their quality. The second goal is to evaluate which partial metrics are the most essential for accuracy prediction of machine transcription.
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Software ECG generator
Hendrych, Marek ; Smital, Lukáš (referee) ; Vítek, Martin (advisor)
The diploma thesis deals the cretion of the ECG signal and its potential morphology. A signal is generated using a program that is created in MATLAB. On the basis of these methods of describing the signal, was chosen method, based on the similarity of ECG with sinus respectively. triangular pattern. Generated by the program can draw the ECG signal by assignment of pulse rate, lenght of the signal, sampling rate and modifications of the waves and oscillations. One or more predefined noise can be added to the signal. Generated signal is possible to save to the format that supports program MATLAB.
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Preprocessing of ECG signals for detection of significant points
Strouhal, Martin ; Smital, Lukáš (referee) ; Vítek, Martin (advisor)
This work aims to find out the best filter design method for getting out parasitic elements in ECG signal. There are defined origin and frequency qualities of these elements. Individua filter design methods are compared according to number of filter coefficients, effectivity and influenc to useful signal. I created several digital filters by various design methods and tested them on ten ECG signals. From the experiment ensued: all filters were able to get out brum, but filters designed by distribution of zeros and poles had the lowest number of coefficients. On the other hand same filters were disable to get out drift with very sheer course.
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ECG quality estimation
Pospíšil, Jan ; Smíšek, Radovan (referee) ; Smital, Lukáš (advisor)
This bachelor thesis deals with the question of estimation of the quality of the ECG signals, which is a key parameter for determining the diagnosis. The theoretical part deals with the basic knowledge concerning cardiac physiology, electrocardiography and finally the types of interferences that can occur during the measurement. The following practical part will deal with the published methods and the proposal of methods for estimating signal quality and their testing on artificial and real data.
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Wavelet Filtering of ECG Signals
Mrázek, Jiří ; Vítek, Martin (referee) ; Smital, Lukáš (advisor)
This thesis deals myopotential denoising of ECG signals with using wavelet transform. There was used wavelet denoising subsequently wiener wavelet filtering. In both cases were found the most suitable coeficients for the best denoising. It is meant mainly settings suitable parameters for ideal filtration setting value of threshold, number of decomposition level, selection of thresholding and type of filter. These parameters are tested on real signals. Denoising is realized in Matlab version R2009b.
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ECG quality evaluation
Vencel, Michal ; Vítek, Martin (referee) ; Smital, Lukáš (advisor)
This seminar work deals with the topic of evaluating the quality of ECG signals. The introductory chapters explain the basic characteristics of ECG signals - measurement, the form of the measured signal, methods of analysis. The cardiac physiology and pathology is presented. The most common types of noise that occur in ECG signals are also mentioned. Further, the reader is acquainted with the importance of the issue of evaluating the quality of ECG signals. In the practical part of the work, two own methods for ECG quality evaluation are presented. First, a brief theoretical introduction to the techniques used in the creation of methoda is given, followed by a description of the principle of algorithms. In order to compare the functionality of the proposed methods, three more methods from other authors are presented. Their principle is briefly described. In the final chapter, all methods are subjected to functionality testing. The results are examined and all methods are compared with each other.
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Multilead decision rules in detection of QRS complexes
Šikner, Tomáš ; Smital, Lukáš (referee) ; Vítek, Martin (advisor)
QRS complex is the most significant component of the ECG signal. Detection of the QRS complex is the first step to analyze the ECG signal. It serves as a starting point to measure out of the signal. The single-lead detector and the multi-lead detector are carried out in this work. Both detectors are designed in Matlab. The detectors use the characteristic steep slope of the QRS complex to its detection. The detectors were tested on the CSE database.
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Sleep apnea detection from ECG records
Trnková, Simona ; Smital, Lukáš (referee) ; Králík, Martin (advisor)
The aim of this work is to propose an algorithm for the detection of sleep apnea from the respiratory signal that was extracted from the ECG signal. The work includes the theory of sleep medicine, methods for extracting the respiratory curve from the ECG signal and methods for detecting apnoeic sections. In the practical part, the algorithm for estimating the breathing curve and models classifying apnoeic sections are described and evaluated.
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