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Measurement of the Mechanical Stability of Buildings and Consoles Used for the FSO Links
Kočvara, Pavel ; Němeček, Jiří (referee) ; Wilfert, Otakar (advisor)
The Master's thesis deals with the determination of measurement method of deflection the axis of the optical beam from its ideal position, which is caused by action of force of strong winds affecting the positional stability of the building or supporting structure (tower) used for placement of FSO links'heads. The thesis informs the readers about the other causes of deflection of beam axis in a real environment, about methods of determining the position of the beam axis in the plane perpendicular to the beam axis and the basic properties and parameters of the Gauss beams, including the phenomenon of diffraction on the output aperture of the laser transmitter.
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Stabilization for optical receiver
Kolka, Z. ; Barcík, P. ; Novotný, Jan ; Biolková, V.
Free-Space Optics (FSO) is a wireless optical technology for line-of-sight communications. The front of the receiving optical fiber is located at the focus of the telescope. The relatively small diameter of the core puts extreme demands on receiver pointing under atmospheric turbulences and mounting bracket vibrations. To ensure stability, the beam is stabilized by a fine positioning system. A detection unit evaluates the position of the centre of the laser spot using photodiodes and compensates for deviations by changing the mirror angle.
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Measurement of the Mechanical Stability of Buildings and Consoles Used for the FSO Links
Kočvara, Pavel ; Němeček, Jiří (referee) ; Wilfert, Otakar (advisor)
The Master's thesis deals with the determination of measurement method of deflection the axis of the optical beam from its ideal position, which is caused by action of force of strong winds affecting the positional stability of the building or supporting structure (tower) used for placement of FSO links'heads. The thesis informs the readers about the other causes of deflection of beam axis in a real environment, about methods of determining the position of the beam axis in the plane perpendicular to the beam axis and the basic properties and parameters of the Gauss beams, including the phenomenon of diffraction on the output aperture of the laser transmitter.
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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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