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Analysis of the spectrum of cymbals and their time envelopes
Adamják, Adam ; Musil, Jaroslav (referee) ; Jirásek, Ondřej (advisor)
This Bachelor Thesis deals with the analysis of idiophones, the description of the measuring chain, and the analysis of the spectrum and time course of the measured samples. Based on spectral analysis, individual parameters and influences on the sound of cymbals were evaluated, such as the location of the blow or the type and hardness of the drum sticks. The theoretical basis also deals with the basic theory of the sound signal to the issue of noise and psychoacoustic perceptions. The conclusion deals with the basic mechanical properties and puts them into context with spectral analysis.
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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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Design and optimization of special low-level amplifier for measurement of air ions
Zdražil, Lukáš ; Bartušek, Karel (referee) ; Roubal, Zdeněk (advisor)
This Master thesis deals with low-current measurement in order of picoamps up to a few tens of femtoamps. Such low currents measuring is necessary for determination of air ions concentration. Disturbances, which are otherwise negligible for ordinary measurements must be considered. For example, leakage currents and noise generated in measuring device circuit. The choice of a precise operation amplifier with low input bias current is as important as the selection of low noise passive components. The aim of the thesis is to design and implement a precise low-level amplifier for the purposes of air ions concentration measurements.
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Sensor Security - Verification of Image Authenticity
Juráček, Ivo ; Španěl, Michal (referee) ; Zemčík, Pavel (advisor)
Diploma thesis is about image sensor security. Goal of the thesis was study data integrity gained from the image sensors. Proposed method is about source camera identification from noise characteristics in image sensors. Research was about influence of denoising algorithms applied to digital images, which was acquired from 15 different image sensors. Finally the statistical evaluation had been done from computed results.
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Acoustic generator for evoked potentials stimulation
Škutková, Helena ; Rampl, Ivan (referee) ; Chmelař, Milan (advisor)
Evoked potentials are electric brain response to external stimulus. They are important diagnostic no visual method in neurology. For their excitation use of different of kinds stimulation, most often: visual, auditory, somatosenzory, olfactory and gustatory. Evoked potentials are objective method for measurement sense perception. This master’s thesis is specialized to auditory evoked potentials and design acoustic generator for their stimulation. Auditory evoked potentials are primary used for objective audiometry, but they have another usage. In the first place, application is specialized on health sector. The aim of this master’s thesis is compact specified medical requirements with available technical resources.
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Precise voltage references
Budáč, Peter ; Ing. Miroslav Horáček, Ph.D., ÚPT AVČR Brno (referee) ; Zobač,, Martin (advisor)
The aim of this thesis is the realization of the workplace to measure long-term stability and temperature coefficient of precision voltage references. It analyses individual solutions precision voltage references and their important parameters for the stability of the reference voltage. It deals with the influence of thermoelectric voltages and methods how to minizme their effect on measurement error . In conclusion it proposes a solution of this measuring workplace, and evaluate the results measuring of long-term stability and temperature coefficient on selected precision voltage references.
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Evaluation of classification efficiency using ROC cruves
Dluhý, Vojtěch ; Sigmund, Milan (referee) ; Poměnková, Jitka (advisor)
This semestral thesis is focused on work eith the ROC curves. Introduces the reader with ROC curves and their use to analyzing signals. Also shows an algorithm for detecting sound of siren in record using a simple algorithm and evaluation of various jamming sound of sirens by displaying the ROC curves, supplemented by calculation and comparing the areas under these curves (AUC). The algorithm is written in a development enviroment Matlab.
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Identification of Speech Activity in Noisy Speech Signal
Pelikán, Martin ; Sysel, Petr (referee) ; Smékal, Zdeněk (advisor)
This paper is focused on identification of pauses in noisy speech signal and following filtering of the noise from the signal. Firstly the signal processing methods are theoretically described, then voice activity detectors and in the end noise filtering methods are described. Several voice activity detectors were created and their pause detection rate was compared.
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Precision audio preamplifier for headset measurement
Šimek, Michal ; Balík, Miroslav (referee) ; Hanák, Pavel (advisor)
This thesis deals with microphone and headphone preamplifier for microtelephone and headset. The design shall meet the electrical interface requirements set out in ITU-T Rec. P.381(08/2012). The design includes a voltage converter, microtelephone bias and both a battery and an external power supply. In this work is also described the design of printed circuit board and the solution of a low noise in the whole circuit. The aim of this thesis is to design, built and embed the laboratory fixture into a metal box. Finally, measure the product on an APx525 audio precision analyzer.
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Noise diagnostics of rectifier diodes PN junctions
Klimíček, Jaromír ; Macků, Robert (referee) ; Raška, Michal (advisor)
The thesis deals with the design of the measurement installation, which is intended for the microplasma noise measurements. This noise is being generated in the defective parts of the PN junction. The goal of this work is to design the measurement installation and to realize the fully functional workbench for the analogical noise related measurements and to determine the transfer function of the measurement installation. Main part of the work is to choose proper parameters for the measuring devices and to design the software intended for the automated measurements. Consequently, we have to process the measured waveforms of the microplasma noise, to determine the dependency of the noise on the signal magnitude and to calculate the power spectral noise density. Finally, we have to determine the transfer function of the measurement installation and to design the inversion filter.
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