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Power LED control using ATtiny
Martynek, Tomáš ; Kubánek, David (referee) ; Balík, Miroslav (advisor)
Target of this bachelor’s thesis is to develop suitable DC/DC converter for driving power LED with Atmel Tiny micro. There is PHILIPS white power LED – Luxeon Star/O as the light source used. Micro’s AD converter measures current through this LED. This value is used for current driving using PWM micro output. Whole device is accumulator powered, design allows usage of three AA alkaline batteries instead of NiMH accumulators. During design phase was choosing between 2 and 3 AA batteries power solution. Because of the longest working time, the final solution uses 3 AA batteries – in this configuration works the flashlight about 7 hours. Flashlight can charge NiMH batteries from external constant current power source. Micro controls whole charging process and disconnects accumulators from current source after full charge using method of negative voltage change. Timer method is backup method in case, when negative voltage drop is very small – the charging time is limited to max. 9 hours. Micro can detect bad or non-possible charged cells.
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Design and Implementation of Active Loudspeaker System with Digital Input
Uchytil, Filip ; Balík, Miroslav (referee) ; Schimmel, Jiří (advisor)
The work is focused on a design of an active loudspeaker system with a bi-amp amplifier and a digital input. There is described the theory of a loudspeaker enclosure design and its practical implementation. Furthermore the work deals with a design and construction of input circuits such as a preamplifier, Baxandall tone control, active crossover, all-pass filter and S/PDIF. On the basis of the amplifier´s theory the optimal construction of amplifiers and their design are selected. The complex design of the loudspeaker box is devised so that it would reach a maximum acoustic power during the preservation of a low distortion.
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Simulations of auditory space and azimuth&distance of sound source, for multichannel sound systems
Orlovský, Kristián ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
This thesis is aimed at simulation of auditory space. It describes the most frequently used panning method: Vector Base Amplitude Panning. Also is focused on image source method, which allows computing the parameters of direct sound wave and reflections in rectangular room. This method is compared with ray–tracing method, which is also often used. It deals with the matter of the frequency – dependent absorption of materials in reflection of the sound wave against the wall. On the basis of these information two applications were designed in MATLAB development environment. The first one allows the simulation of auditory space. The other one is the application for sound source panning by its azimuth and distance.
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Modern pitch-shifting algorithms and its aplication in virtual musical instruments
Křupka, Aleš ; Balík, Miroslav (referee) ; Trzos, Michal (advisor)
This diploma thesis deals with pitch shifting methods of acoustical signals. The theoretic part of this thesis involves description of three different pitch shifting techniques, these are the method using a modulated delay line, PICOLA method and method using a phase vocoder. The first two methods represent the processing in time domain, the third method represents the processing in frequency domain. In relation with the PICOLA method, the thesis also mentions algorithms for pitch estimation. The practical part demonstrates the use of these methods. There is described a sampler virtual musical instrument based on the playback of the sounds stored in memory. In this part the particular units providing the required functionality are described. The generating of sounds is controlled by the MIDI protocol. In the sampler is implemented the PICOLA method.
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Advanced method of signal time-stretching based on tonal and non-tonal segment detection
Vomáčka, Jan ; Trzos, Michal (referee) ; Balík, Miroslav (advisor)
This thesis deals with the method for time conversion of an audio signal based on a different approach to groups tonal and non-tonal segment signal implemented in Matlab. The first part deal with methods for musical signal processing based on time compression or expansion and describes the problems associated with the current way of implementing these methods. The following describes the methods of variable segmentation and tonal and non-tonal components detection in the audio recording. At the second part are these methods of variable segmentation, tonal component detection and time compression or expansion implemented in MATLAB. At the third part is performed testing on sound recordings and evaluation of results.
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Software implementation of the subjective assessments of sound quality
Špeta, Marek ; Balík, Miroslav (referee) ; Rášo, Ondřej (advisor)
The focus of this diploma thesis is on methods for the subjective assessment of sound quality according to recommandations given by International Telecommunication Union ITU. The thesis is thematically divided into four parts. The first part is an interpretation of methods based on internationally accepted standards (method of small impairments, MUSHRA, general methods). The second part describes the functional blocks of application developed for this thesis in LabVIEW enviroment. Next part explains its practical application, especially its running possibilities. The last part describes a listening experiment, aim of which was to verify the application's features and to compare the results of the subjective method used in the experiment with the results of the objective method PEAQ.
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Acoustical analysis of mechanical watsches
Dohnal, Marek ; Balík, Miroslav (referee) ; Sigmund, Milan (advisor)
This thesis is focused on the analysis of the characteristics of mechanical watches on the basis of their sound. There are theoretically analysed usual mechanical defects and disorders of watches and compensation of those defects. Particular attention is given to disorders, that can be extracted from the recorded acoustic sound of watches. There are also solved most appropriate methods of recording with a respect to the minimisation of ambient acoustic interference. The main part of this work is experimental measurement on watches and evaluation of achieved acoustic data. For this purpose, an autonomously running software were developed.
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Variable segmentation for sound signal processing
Garai, Szabolcs ; Míča, Ivan (referee) ; Balík, Miroslav (advisor)
This paper describes the methods used mainly in the filtration of audio signals -- noise reduction. It realizes segmentation with variable lenght of segment, constant overlap add and segmentation with variable lenght of segment and overlap add. These methods are then compared with comon methods of segmentation in dependance of the lenght of segment and used window function by the thresholding method. For this purpose it uses the database of audio records. In the first part it desrcibes the technique of audio signal processing with comon method of segmentation. According to this method it continues in design of signal processing by variable segmentation method, in which it is needed to modify the shape of window function, which influences and attributes are explained in next chapter. In practical part it describes the implemented methods in MATLAB programming language with each steps of testing. It continues with chart of enclosed files and the evaluation of the results of hearing tests.
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Subjective and Objective Assessment of Speech Quality
Bezdíček, Martin ; Balík, Miroslav (referee) ; Vondra, Martin (advisor)
This Bachelor's thesis is focused on subjective and objective methods for evaluation of speech quality. In the first part, the quality of transmitted speech signal and its distorting effects are given. Futher, subjective and objective methods for evaluation of speech are described. The objective methods: Signal to Noise Ratio (SNR), Segmental Signal to Noise Ratio (SSNR), the methods for evaluation in spectral area (Log Likelihood Ratio Measures and Cepstral Distance) and also Perceptual Evaluation of Speech Quality (PESQ). The next part deals with the correlation analysis which is used for the comparison of subjective and objective methods. In the last part of the bachelor thesis the results of subjective and objective methods are presented. Finally on the basis of correlation analysis with the results of subjective method, the best objective method is recommended.
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Universal diagnostic device for accumulators
Němec, Filip ; Lattenberg, Ivo (referee) ; Balík, Miroslav (advisor)
Firstly, this bachelor thesis handles the issues concerning NiCD and NiMh batteries and methods used when charging and discharging. Next segment of the document deals with designing and the actual realization of a device, which can work with these batteries and perform variable tasks,such as charging and discharging battery with adjustable current value, measuring temperature of the battery. Sending data via the serial port,it also implements charging and discharging curve. Device can be operated intuitively using buttons and display. The Device is realized via microcontroller ATMEL.
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