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Tube Microphone
Škoda, Adam ; Šotner, Roman (referee) ; Staněk, Miroslav (advisor)
The presented thesis deals with a tube microphone using a condenser microphone capsule for sound capturing. Moreover, two essential aspects of a tube microphone – the basis of its operation and its design – are also discussed in this thesis. In the designed microphone, there is a vacuum tube known as ECC81. This vacuum tube is used as an amplifying element of an input sound signal. This paper also includes the choice of the most suitable microphone circuit, its modification and the design of a voltage source used for feeding and heating the vacuum tube. Some appropriate simulations were applied to find out the functionality of all designed parts of the microphone system. Following step was the practical realization of all microphone parts as well as the activation and the complete parameters and characteristics measurements of realized microphone system. After the provided measurements, the microphone was compared to equivalent commercial products. Evidently, the realized microphone is qualitatively similar to other commercial products. Presented thesis also contains the list of components and PCBs.
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Digital signal processing from MEMS microphones
Koníček, Cyril ; Pristach, Marián (referee) ; Fujcik, Lukáš (advisor)
Proposed bachelor thesis is focused to the filter design for digital signal processing from digital microphone (MEMS type). The microphone types, structure of AMDP421 digital microphone and digital filter types are described in details. Selected filters are modelled, designed and simulated in MATLAB tool to meet the filter specification. The results are sufficiently commented and assessed. Afterwards the digital filters are described in VHDL language and implemented to the target FPGA circuit. In frame of the work the extended modules to SPARTAN 3 STARTER KIT are developed and designed to evaluate and demonstrate the proper function of the proposed filter design.
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SAW resonator controlled FM transmitter
Pokorný, Josef ; Frýza, Tomáš (referee) ; Kolouch, Jaromír (advisor)
This thesis describes design of FM transceiver with SAW resonator. Theoretically analyzes properties of microphone, oscillator and choosing of fitting antenna where it's analyses theirs strong and weak sides. Transceiver has electret microphone. Signal from microphone is amplified by preamplifier OPA134. Further this paper contains oscillator build which output is amplified by monolithic power amplifier and routed through RF filter to antenna.
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Tube microphone preamplifier
Čacký, Adam ; Hruboš, Zdeněk (referee) ; Brančík, Lubomír (advisor)
The theme of the master´s thesis is design a microphone preamplifier which uses vacuum tube as a main amplifying element. Part of the work is theoretical assumptions for the optimal design and implementation of peripheral involvement, comparing the properties of components used and the resulting parameters of modeled device. The thesis also includes a proposal of the source unit for supplying all parts of the preamplifier. The results are accompanied by circuit simulations and laboratory measurements of the main parameters of the designed device.
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Spectral analyse of sound in space acoustics
Port, Martin ; Bereznanin, Martin (referee) ; Rozman, Jiří (advisor)
This thesis is an introduction to the problems of acoustics and is focused on the variables describing the noise. The methodology for measuring noise in relation with valid hygiene standards is analyzed in next section. The noise levels at work required by government regulation no. 148/2006 are summarized in a subsequent charter. The next section is an introduction to the analyzer PULSE 3560B from Brüel & Kjar. This work describes a software called Labshop, which is designed to analyze noise and vibrations. It also describes the most common features Acoustilyzer NTI AL1. The practical part was to measure the reverberation, noise, frequency spectrum and plott the distribution of noise with noise maps of various auditoriums.
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Localization of Combustion Engine Noise Origin with the use of Acoustic Emission
Rasch, František ; Mazůrek, Ivan (referee) ; Klíčník,, Martin (referee) ; Pražák, František (referee) ; Píštěk, Václav (advisor)
This doctoral thesis deals with the diagnostics of combustion engines, which have clearly suffered a mechanical damage. The text describes a basic principle of a diagnostics based on an observation of a noise of a running engine. There are mentioned the basic methods of a noise recording with direct conection to the specifics of measurement a running combustion engine noise. The introduction describes the spread of a vibration in solid structures. For the combustion engine vibration and source of noise is dedicated an independent chapter, which focuses on all noise generators, not only mechanical and thermodynamic but also noise caused by fluid and gas flowing. An integral part of the thesis is also a list and examples of signal processing, serving for efficient localization of the noise root cause. The noise statistics are compared with event diagram of engine investigation. Considering the information of the crank shaft position, we are then able to localize a possible root cause of the mechanical problem. For this purpose unique computer software for MS Windows operation system was developed. This system is able to generate event timelines of the piston engines. The inputs are basic engine data, such as the number of cylinders, ignition sequence, valve timing diagrams and information regarding two stroke or four stroke engine types. The program also allows us to detect a potential damage by direct comparison of the engine timeline and noise signal input. The thesis is also supplemented by measurements serving for key-parameter-diagnostics, i.e. the selection of the most suitable running engine operation. Comparison of different technical diagnostic approaches shows the suitability of mentioned diagnostic process.
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Network with capacitor microphone using FM modulation
Lapáček, Petr ; Říha, Kamil (referee) ; Káňa, Ladislav (advisor)
In bachelor's thesis I was interested in quality of the electrostatic transducer. I have described a theoretic pieces of knowledges in parts of FM modulations and the variables crystals oscillators. I have tried to propose a conception of the condenser mikrophone in the high-frequency circuit where one of the main part was the crystal oscillator, which part was the capacitor transducer, in capacity element representative uncertain capacities. By this way I have tried to create the modulator, whose modulation depend on the actual changes of capacities in the electrostatic changers. Finally I have interested in the demodulation in this way of creating the HF signal by the help of detection unit TDA7000 and likewise setup of integrated circuit.
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