|
|
Automatic Classification of Digital Modulations
Kubánková, Anna ; Novotný, Vít (advisor)
This dissertation thesis deals with a new method for digital modulation recognition. The history and present state of the topic is summarized in the introduction. Present methods together with their characteristic properties are described. The recognition by means of artificial neural is presented in more detail. After setting the objective of the dissertation thesis, the digital modulations that were chosen for recognition are described theoretically. The modulations FSK, MSK, BPSK, QPSK, and QAM-16 are concerned. These modulations are mostly used in modern communication systems. The method designed is based on the analysis of module and phase spectrograms of the modulated signals. Their histograms are used for the examination of the spectrogram properties. They provide information on the count of carrier frequencies in the signal, which is used for the FSK and MSK recognition, and on the count of phase states on which the BPSK, QPSK, and QAM-16 are classified. The spectrograms in that the characteristic attributes of the modulations are visible are obtained with the segment length equal to the symbol length. It was found that it is possible to correctly recognize the modulation with the known symbol length at the signal-to-noise ratio at least 0 dB. That is why it is necessary to detect the symbol length prior to the spectrogram calculation. Four methods were designed for this purpose: autocorrelation function, cepstrum analysis, wavelet transform, and LPC coefficients. These methods were algorithmized and analyzed with signals disturbed by the white Gaussian noise, phase noise and with signals passed through a multipass fading channel. The method of detection by means of cepstrum analysis proved the most suitable and reliable. Finally the new method for digital modulation recognition was verified with signals passed through a channel with properties close to the real one.
|
|
|
Processing of heart sounds signals
Němcová, Simona ; Matějková, Magdaléna (referee) ; Vondra, Vlastimil (advisor)
This bachelor thesis is focused on the heart sound signal. It describes the principles of hear sound formation, measurement methods and especially the analysis of the measured phonocardiography signal. In the practical part of this thesis, the algorithm for detecting the first and the second heart sounds is designed by using MATLAB software. Its principle is realized in finding maximum or center of gravity in the filtered phonocardiography signal.
|
|
|
Measurement of ECG signal for TWA analysis
Řezáč, Petr ; Vítek, Martin (referee) ; Kozumplík, Jiří (advisor)
The thesis deals with possibilities of using wavelet transform in the field of surface electrocardiogram (ECG) signals denoising and ECG signals measuring. Several algorithms have been used to detect and estimate T-wave alternans (TWA), such as spectral method (SM), Poincaré Mapping (PM) or correlation method (CM). T-wave alternans, also called repolarization alternans, is a phenomenon appearing in the electrocardiogram as a consistent fluctuation in the repolarization morphology on every-other-beat basis. Electrical TWA has been recognized as a marker of electrical instability, and has been shown to be related with patients at increased risk for ventricular arrhytmias. Presence of TWA has been reported in a wide range of clinical and experimental situations including long QT syndrome, myocardial infarction, angina pectoris, acute ischemia, etc. Projected methods of detection TWA are realized in Matlab software, and they are experimentally verified on real ECG signals from the European ST-T Database.
|
|
|
Time-Frequency Signal Analysis
Kubala, Matej ; Polok, Lukáš (referee) ; Bařina, David (advisor)
This bachelor thesis is dealing with explanation of time-frequency signal analysis. Basic definitions and terms of signal processing and spectral analysis will be explained, especially focused on transfer time domain into freqency and inverse. The main objective of thesis is to explain in detail and compare two of the most popular methods, Fourier transform and Wavelet transform. Results will be illustrated on implemented application, which loads sound record and computes frequency in specific time using these methods.
|
|
|
Noise reduction for low dose CT data
Holub, Zbyněk ; Odstrčilík, Jan (referee) ; Chmelík, Jiří (advisor)
The aim of this work is comparing of methods which are used for filtration of low dose CT images. This filtration is realized due to suppress of noise in final image and better visble of details. This work contains design and realization of selected filtration methods. Wiener´s correction coefficient and filtration with usage of WAVELET TRANSFORM are introduced in detail view. These methods are created in Matlab®; with the option to set para-meters of filteres. The filters are tested on 3D CT lungs image data. In the end of this work is a ranking of filter‘s quality and choosen of the most optimal approach.
|
|
|
ECG noise influence on compression using SPIHT algorithm
Bartošovský, Petr ; Vítek, Martin (referee) ; Hrubeš, Jan (advisor)
The thesis provides an analysis of the ECG signal, focusing on the possible types of interference occuring in the signal. These types of interference are closely examined and their realization in the MATLAB programming environment is characterized. The SPIHT algorithm is introduced and the possibilities of its use are discussed. Futher, the application of this algorithm to the ECG signal containing individual types of interference generated by means of the designed interference generator is described and the impact of the SPIHT algorithm on the specific types of signal interference is analyzed. Finally, the obtained results are evaluated.
|
|
|
Restoration of overexposed digital image
Zonygová, Kristýna ; Veselý, Vítězslav (referee) ; Rajmic, Pavel (advisor)
The Bachelor thesis deals with the recovery of overexposed grayscale images based on sparse signal representation. For image conversion to another representation wavelet transform was used. In this representation, the solution of convex optimization which demand on relax signal sparse and restored pixels values was searched for. In this case, the proximal Douglas-Rachford algorithm was applied which uses two proximal operators. The implementation was carried out in numerical computing enviroment MATLAB using the Wavelet Toolbox software. The PSNR (peak signal-to-noise ratio) was utilized to evaluate success rate of proposed method. The method was tested on 5 random images and compared to results of image manipulation software Adobe Photoshop Lightroom CC.
|
|
|
Restoration of overexposed digital image
Zonygová, Kristýna ; Veselý, Vítězslav (referee) ; Rajmic, Pavel (advisor)
The Bachelor thesis deals with the recovery of overexposed grayscale images based on sparse signal representation. For image conversion to another representation wavelet transform was used. In this representation, the solution of convex optimization which demand on relax signal sparse and restored pixels values was searched for. In this case, the proximal Douglas-Rachford algorithm was applied which uses two proximal operators. The implementation was carried out in numerical computing enviroment MATLAB using the Wavelet Toolbox software. The PSNR (peak signal-to-noise ratio) was utilized to evaluate success rate of proposed method. The method was tested on 5 random images and compared to results of image manipulation software Adobe Photoshop Lightroom CC.
|
|
|
Noise reduction for low dose CT data
Holub, Zbyněk ; Odstrčilík, Jan (referee) ; Chmelík, Jiří (advisor)
The aim of this work is comparing of methods which are used for filtration of low dose CT images. This filtration is realized due to suppress of noise in final image and better visble of details. This work contains design and realization of selected filtration methods. Wiener´s correction coefficient and filtration with usage of WAVELET TRANSFORM are introduced in detail view. These methods are created in Matlab®; with the option to set para-meters of filteres. The filters are tested on 3D CT lungs image data. In the end of this work is a ranking of filter‘s quality and choosen of the most optimal approach.
|
|
|
Processing of heart sounds signals
Němcová, Simona ; Matějková, Magdaléna (referee) ; Vondra, Vlastimil (advisor)
This bachelor thesis is focused on the heart sound signal. It describes the principles of hear sound formation, measurement methods and especially the analysis of the measured phonocardiography signal. In the practical part of this thesis, the algorithm for detecting the first and the second heart sounds is designed by using MATLAB software. Its principle is realized in finding maximum or center of gravity in the filtered phonocardiography signal.
|
guest ::
