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Integrated multichannel audio amplifier for home cinema
Fišer, Ondřej ; Šotner, Roman (referee) ; Kratochvíl, Tomáš (advisor)
This paper describes complete design of amplifier for home cinema system. Described amplifier has 2 digital inputs (TOSLINK and S/PDIF) and single analog input. With this inputs it is possible to connect amplifier to a source of surround audio 5+1 signal. Paper further discuss design of correction circuits, preamplifier, power amplifier and power source. The whole is controlled by 8-bit microprocessor and has a graphics output implemented through LCD display. The goal of this paper is to design and build high quality amplifier.
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BIT ERROR RATE AND AVAILABILITY OF THE ATMOSPHERIC OPTICAL LINKS
Kvíčala, Radek ; Vašinek, Vladimír (referee) ; Fišer, Ondřej (referee) ; Wilfert, Otakar (advisor)
This dissertation deals with the problematic of the free space optical link availability determination. For the presumption of the free space optical link unavailability we have to know statistical distribution of the atmospheric attenuations. In this work is also presented the measurement of these atmospheric attenuations with the specially designed optical link. Measurement is using switching of the two separate transmitters with wavelengths of 830 nm and 1550 nm. Presented statistic distribution let us determine the suitability of the link in the chosen locality during its design. Comparison of our measurement with other models like model based on the meteorological visibility is also presented. The last part of this work is focused on the preconditions for the hi-speed network bit error rate determination. Sample of the bit error rate measurement obtained by our designed bit error rate tester is attached.
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Modeling of the multichannel optical wireless link
Pavlů, Michal ; Fišer, Ondřej (referee) ; Poliak, Juraj (advisor)
This thesis deals with multi-channel wireless links with a higher range designated for free-space communications in an atmospheric media. Propagation of the optical beam in an atmosphere is analysed and various influences affecting the quality of the transmitted signal are described. The simulation is carried out for dual optical link. Link budget of individual paths working at the wavelengths in the atmospheric windows – 850 nm and 1550nm. It also examined optical intensity distribution of the transmitted beam. At the end of the work performed measurements and simulations verify the accuracy of the components used in wireless link.
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On Forward and Backward Scattering from Fog and Rain Drops
Fišer, O. ; Rejfek, Luboš ; Brázda, Vladimír
This contribution deals with the backward and forward scattering on dielectrical spheres. The well-known Rayleigh, Mie and Optical regions are discussed for frequencies regions 0.05 to 70 GHz and for optical wavelength of 830 nm. Some of our results fit the published one, some of them are different and the explanation of possible reasons is added. Also the formulas necessary to compute the radar reflectivity or attenuation due to fog and rain are presented.
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Device for Measurement of Optical Visibility
Rejfek, L. ; Brázda, V. ; Fišer, Ondřej
This paper is about a proposed device for the optical visibility measurement. This device is usable for monitoring of the fog mightiness. The principle of device is based on comparison of attenuation on two optical links. The fog mightiness is determined by the using of the Beer-Lambert Law. The philosophy of electrical arrangement is also explained.
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Applied research at the Institute of Atmospheric Physics Prague
Fišer, Ondřej ; Jaroš, J. ; Brázda, V.
This article describes the research performed at the Milesovka observatory. The base of this research is the measurement of the signal attenuation on the experimental free space optic link. Concurrently the pertinent meteorological parameters are measured and compared to the attenuation. First of all, visibility, liquid water content, wind speed + other wind parameters and rain rate are sampled and statistically evaluated including diurnal variations.
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Rain impact on FSO link attenuation based on theory and measurement
Brázda, V. ; Schejbal, V. ; Fišer, Ondřej
The FSO link becomes a usual mean of modern wireless communications. But it suffers from atmospheric particles causing attenuation. That´s why this random attenuation must be carefully considered by the FSO link design. As it is known the most serious atmospheric phenomenon is fog, and low cloudiness. But the rain attenuation (night mare of mm wave links) is not negligible on optical links, too. In this contribution we focus on rain attenuation from theoretical as well as experimental point of view. Statistics and rain event analysis are shown. There is an overview and a comparison of several formulas for rain attenuation derived from DSD or rain rate. Rain is not the worst phenomena for the transmission but we can’t neglect its influence on FSO. Only full understanding of influence of real atmosphere can lead to solution of a high availability of FSO systems.
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Impact of the global crisis on the international trade
Fišer, Ondřej ; Bolotov, Ilya (advisor) ; Černá, Iveta (referee)
The aim of this thesis is to clarify, which factors have led to the formation of the Late-2000 financial crisis and to describe the effects of the crisis on the international trade. The thesis is divided into two chapters. First chapter describes chronologically the sequence of events leading to the crisis and the transmission mechanisms which have caused the collapse of international trade in 2009. Particular emphasis is placed on analysis of the failure of U.S. mortgage market and stock and securities market. Second chapter as the main part of the thesis describes the consequences of the crisis for the individual markets and international trade. Significant space is dedicated to the automotive industry as one of the most important industries. Furthermore, the thesis describes the protectionist measures and analyses their impact on the trade. Lastly, the thesis deals with the description of new trends and predictions of the direction the international trade in the new market reality.
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