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Beamforming using microphone arrays
Bartoň, Zdeněk ; Schimmel, Jiří (referee) ; Míča, Ivan (advisor)
The aim of the master thesis is to sum up theoretical information about beamforming methods of microphone arrays and to verify their functionality. At the beginning of this work there are simulated different varietes of linear uniform and nonuniform microphone arrays and circular arrays. The results are verificated by a practical measurement in ideal conditions. Then I will focuse on implementation of the DAS(Delay And Sum), SAB(Sub Array Beamforming), CDB(Constant Directivity Beamforming), CDB-CA(CDB-Circular Arrays) beamformer including theoretical and practical verification of the functionality in ideal conditions. At the end of this thesis are all beamforming methods compared with each other at SNR(signal to Noise Ratio) and directivity parameters.
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ECG quality evaluation
Scholasterová, Viktorie ; Němcová, Andrea (referee) ; Smital, Lukáš (advisor)
This bachelor’s thesis deals with ECG quality evaluation. Its main goal is to examine the theoretical basis for a realization of selected methods for ECG quality evaluation. In the theoretical part of the thesis there is described electrocardiography, morphology of electrocardiogram, types of signal interference and Holter recorders. A basic procedure of ECG quality evaluation including filtration, detection of important characteristics of ECG signal and an overview of chosen methods follows. The practical part contains a description of three methods for ECG quality evaluation – a method of average heart rate, a method of calculation signal-to-noise ratio (SNR) and a method of band-pass filters. Finally, the results of the methods using artificial data, real-time data and data from a competition PhysioNet/Computing in Cardiology Challenge 2011 are evaluated.
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Measurement of noise characteristics of MEMS accelerometers
Mihaľko, Juraj ; Klusáček, Stanislav (referee) ; Beneš, Petr (advisor)
The aim of this bachelor`s thesis was to determine noise static parameters of MEMS accelerometers. It is a limiting parameter for the activity with them. If the manufacturer gives the values of MEMS accelerometers noise compare them with measured values. The work contains comparison the noise of cards and determines which is better suited to measuring chain for measuring noise. Noise of the MEMS accelerometers was measured in static mode. Next step was to propose measurement setup for evaluation noise parameters of MEMS accelerometers in dynamic mode. For evaluation noise in dynamic mode was used new card. The possibility of using this measurement setup was verified. In dynamic mode were noise of three MEMS accelerometers in axis Z measured and one three-axis accelerometer in all three axis.
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Adaptive OFDM
Nowak, Dan ; Valenta, Václav (referee) ; Maršálek, Roman (advisor)
The purpose of this paper is to study the possibilities of the OFDM system adaptive modulation. The study presents mechanism for acquiring the necessary data of every frequency subchannel using pilot signals and application of these data for system adjustment. The paper introduces the water-filling principle for subchannel power allocation on the basis of their SNR and adaptive modulation mechanisms for variety of OFDM usage. These mechanisms are implemented into a MATLAB model. The code is then transformed into graphical representation and using USRP2, the signal is transmitted by real world channel.
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Assessment of speech signal quality
Tuleja, Peter ; Balík, Miroslav (referee) ; Míča, Ivan (advisor)
This paper discusses methods for evaluating the quality of the speech signal. Briefly describe the subjective methods for determining the quality of the speech signal. From subjective methods the pair-wise comparison and MOS score are presented. Objective intrusive methods are described in more detailed way - namely methods of the segmental SNR evaluated in time domain, method of the segmental SNR evaluated in the frequency domain and frame normalization method which uses LSE based estimator. At the end of this paper is described an experiment, in which the aforementioned methods are compared and than statistically evaluated.
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ECG quality evaluation
Bracková, Michaela ; Němcová, Andrea (referee) ; Smital, Lukáš (advisor)
This diploma thesis deals with the topic of the ECG quality evaluation. The theoretical part of the thesis contains an overview of the methods, which were studied and an explanation of the basic principles connected with the quality evaluation of the ECG signals. The practical part deals with the implementation of three selected methods, one of which is the continuous evaluation of signal quality by means of SNR (signal to noise ratio) calculation. The results of these methods are further discussed and compared.
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Simulation of synthetic diffusion tensor data
Labudová, Kristýna ; Mézl, Martin (referee) ; Labounek, René (advisor)
This work deals with different approaches to imaging of diffusion intensity with magnetic resonance. Individual approaches are described and compared. Gaussian model for approximation of diffusion profile is analysed and mathematically determined in details. The next part of this work concerns about process of simulation synthetic diffusion tensor data, adding noise to data and estimation of diffusion tensor from noisy data. Estimation’s accuracy is rated according to deviation of fractional anisotropy of estimated and original tensor and also according to deviation of the main eigenvectors of both tensors. Accuracy of the estimation is evaluated automatically with the programme. There is realization of graphical interface for simulation as well as for automatical evaluation of results described in details. At the end of this work all results are processed and commented and there is also recommendation for optimal adjustment of the data acquisition. 120 gradient directions are the most optimal of all analysed direction. It provides sufficient accuracy of results with optimal time of data acquisition which is suitable for clinical praxis.
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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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Segmentation of ECG signals based on their quality
Zobačová, Barbora ; Maršánová, Lucie (referee) ; Vítek, Martin (advisor)
This semestral thesis deals with methods for continuous estimation of the quality of the ECG signal. The theoretical part includes the functional anatomy of the heart, the basics of electrocardiography, the types of noise that can be found in the ECG records, and a description of several methods for the continuous estimation of the ECG signal quality. Next here are some approaches to segmenting ECG signals based on their quality. The practical part deals with the implementation of two methods. The first method is the SNR estimation method based on the Wiener filter. The second method is the method of segmentation of ECG signals based on their quality. Both methods were tested on artificial and real signals.
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Image processing of MRI
Němcová, Simona ; Jiřík, Radovan (referee) ; Krátká, Lucie (advisor)
This thesis deals with the cartilage imaging using magnetic resonance. At first, there is mentioned physical principle of the magnetic resonance phenomenon and the most commonly used excitation sequences, followed by the description of the 9.4 T MR imaging system Bruker BioSpec 94/30 USR, which was used for measurement in the practical part. The next part is dedicated to the composition of cartilages and describes the temporomandibular joint, due to its suitability as an object for cartilage imaging. The series of MR scans of temporomandibular joint were taken with different acquisition parameters and evaluated by program designed through the MATLAB software. The program can be used for viewing scanned images, evaluating their contrast and determining the T1 relaxation time of the tissues by creating T1 maps.
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