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Realization of noise generator
Kalánek, Jakub ; Hadinec, Michal (referee) ; Kubásek, Radek (advisor)
This work occupy practical realization noise generator. The first part is concentrated on description accidental signal. In the second are color and sorts noises. The third part is concentrated on usage noise in practices. In the fourth part are sorts sources noise. The fifeth part is concentrated on circuit design and design easy noise generator and test Zener diode and set work point.
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Noise generator
Pospíšil, Miroslav ; Kubásek, Radek (referee) ; Fiala, Pavel (advisor)
The goal of bachelor’s thesis „Noise generator“ is circuit design and construction of noise generator. The first part is concentrated on description of random signals. There are circuits of noise generators in the second part. In the third part is example of utilization noise generator in microwave sensors. And in fourth part are designed circuit and made measurements.
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Electronic Noise of Piezoceramic Sensors of Acoustic Emission
Majzner, Jiří ; Šikula, Josef (advisor)
In our work the analysis of electrical and noise characteristics of piezoceramic acoustic emission sensors is accomplished. The objective of our work is to analyze and optimize the signal-to-noise ratio. The starting point is the explanation of the noise origin in the acoustic emission sensors. The voltage fluctuation is caused by the dipole vibrations due to their interaction with phonons. The frequencies of dipoles vibrations have statistical distribution and the total energy of these vibrations is proportional to the temperature. The statistical distribution of vibration frequencies leads to the origination of the 1/f type noise spectral density. The interaction between the phonons and electric dipoles is characterized by the imaginary part of susceptibility which is related to the transformation of electric energy to the mechanical energy of vibrations. This process is irreversible and this forms important theoretical question whether the Callen-Welton fluctuation dissipation theorem could be used for the description of fluctuation processes in the acoustic emission sensors. In our work the influence of the real and imaginary part of the susceptibility on the noise and electrical characteristics is solved, the dissipation of electrical energy characterized by the imaginary part of susceptibility is described and the connection between the imaginary part of susceptibility and the noise power spectral density is discussed. Due to the fact that these processes originate in the interaction between electrical dipoles and phonons, we give account of the temperature dependencies of equivalent series resistance and power spectral density of noise voltage, respectively. Piezoceramics stiffness contribute significantly to the resonance creation hence the pressure influence on the sensor noise characteristics was studied. The signal-to-noise ration improvement requires the piezoceramic sample diameter increase for its constant thickness. The ratio of the noise spectral density and sensitivity is independent on the sample thickness. The noise voltage is proportional to the square root of spectral density and frequency bandwidth that is why for the high signal-to-noise ratio it is necessary to minimize the signal amplifier frequency bandwidth. The noise voltage power spectral density increases with the temperature while the activation energy is 20 meV for the temperature 300 K, and 80 meV for the temperature 400 K, respectively. The power spectral density of planar oscillations decreases with increasing pressure and simultaneously the resonant frequency increases. The bandwidth of the normalized spectral density increases with the pressure for the planar oscillations while is invariable for the thickness oscillations. For the examination of the influence of the piezoceramic electrical polarization on the electrical and noise characteristics the experimental study of these dependencies was accomplished for samples without polarization, and samples polarized by electric field EP = 500V/mm and 1000V/mm, respectively. The samples without polarization show the noise of 1/f type only which corresponds to the Callen-Welton fluctuation dissipation theorem. The polarization leads to the generation of planar and thickness oscillations and the power spectral density of voltage fluctuation on the electrodes is proportional to the temperature, and inversely proportional to the imaginary part of permittivity, to the sample area S, and the frequency f.
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Anyalyze of photovoltaic cell by noise diagnostic
Husák, Marek ; Sládek, Petr (referee) ; Vaněk, Jiří (advisor)
The master’s thesis deals with the noise diagnostic in the solar cells. Describes the main kinds of noises. The samples were quality and reliability screened using noise reliability indicators. The samples were surveyed by measuring the I-V characteristics, the noise spectral density as a function of forward voltage and frequency. It was calculated the noise spectral density as a function of forward current.
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Electronic Noise of Piezoceramic Sensors of Acoustic Emission
Majzner, Jiří ; Šikula, Josef (advisor)
In our work the analysis of electrical and noise characteristics of piezoceramic acoustic emission sensors is accomplished. The objective of our work is to analyze and optimize the signal-to-noise ratio. The starting point is the explanation of the noise origin in the acoustic emission sensors. The voltage fluctuation is caused by the dipole vibrations due to their interaction with phonons. The frequencies of dipoles vibrations have statistical distribution and the total energy of these vibrations is proportional to the temperature. The statistical distribution of vibration frequencies leads to the origination of the 1/f type noise spectral density. The interaction between the phonons and electric dipoles is characterized by the imaginary part of susceptibility which is related to the transformation of electric energy to the mechanical energy of vibrations. This process is irreversible and this forms important theoretical question whether the Callen-Welton fluctuation dissipation theorem could be used for the description of fluctuation processes in the acoustic emission sensors. In our work the influence of the real and imaginary part of the susceptibility on the noise and electrical characteristics is solved, the dissipation of electrical energy characterized by the imaginary part of susceptibility is described and the connection between the imaginary part of susceptibility and the noise power spectral density is discussed. Due to the fact that these processes originate in the interaction between electrical dipoles and phonons, we give account of the temperature dependencies of equivalent series resistance and power spectral density of noise voltage, respectively. Piezoceramics stiffness contribute significantly to the resonance creation hence the pressure influence on the sensor noise characteristics was studied. The signal-to-noise ration improvement requires the piezoceramic sample diameter increase for its constant thickness. The ratio of the noise spectral density and sensitivity is independent on the sample thickness. The noise voltage is proportional to the square root of spectral density and frequency bandwidth that is why for the high signal-to-noise ratio it is necessary to minimize the signal amplifier frequency bandwidth. The noise voltage power spectral density increases with the temperature while the activation energy is 20 meV for the temperature 300 K, and 80 meV for the temperature 400 K, respectively. The power spectral density of planar oscillations decreases with increasing pressure and simultaneously the resonant frequency increases. The bandwidth of the normalized spectral density increases with the pressure for the planar oscillations while is invariable for the thickness oscillations. For the examination of the influence of the piezoceramic electrical polarization on the electrical and noise characteristics the experimental study of these dependencies was accomplished for samples without polarization, and samples polarized by electric field EP = 500V/mm and 1000V/mm, respectively. The samples without polarization show the noise of 1/f type only which corresponds to the Callen-Welton fluctuation dissipation theorem. The polarization leads to the generation of planar and thickness oscillations and the power spectral density of voltage fluctuation on the electrodes is proportional to the temperature, and inversely proportional to the imaginary part of permittivity, to the sample area S, and the frequency f.
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Realization of noise generator
Kalánek, Jakub ; Hadinec, Michal (referee) ; Kubásek, Radek (advisor)
This work occupy practical realization noise generator. The first part is concentrated on description accidental signal. In the second are color and sorts noises. The third part is concentrated on usage noise in practices. In the fourth part are sorts sources noise. The fifeth part is concentrated on circuit design and design easy noise generator and test Zener diode and set work point.
|
|
|
Anyalyze of photovoltaic cell by noise diagnostic
Husák, Marek ; Sládek, Petr (referee) ; Vaněk, Jiří (advisor)
The master’s thesis deals with the noise diagnostic in the solar cells. Describes the main kinds of noises. The samples were quality and reliability screened using noise reliability indicators. The samples were surveyed by measuring the I-V characteristics, the noise spectral density as a function of forward voltage and frequency. It was calculated the noise spectral density as a function of forward current.
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Noise generator
Pospíšil, Miroslav ; Kubásek, Radek (referee) ; Fiala, Pavel (advisor)
The goal of bachelor’s thesis „Noise generator“ is circuit design and construction of noise generator. The first part is concentrated on description of random signals. There are circuits of noise generators in the second part. In the third part is example of utilization noise generator in microwave sensors. And in fourth part are designed circuit and made measurements.
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Assessment of noise sources in resistors
Kuparowitz, T.
Thermal noise and 1/f noise are investigated at room conditions in three kinds of basic off-the-shelf resistors. Samples of carbon film, metal oxide, and cement fixed wire-wound resistors are evaluated. Measurement setup is created to acquire their noise spectral density. Their Noise Index and Hooge's constant are calculated and their useability in low-noise measurement setup is assessed.
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