Stanislav Hejduk

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Agri-environmental measures often require postponing of grassland defoliation until summer months. We investigated how this affects agronomic characteristics, i.e., biomass production and forage quality, in species-rich grasslands in the White Carpathian Mountains, Czech Republic. Three distinct grasslands (vegetation alliances Bromion erecti, Cynosurion(More)
This article deals with the design of construction of new type of transmitter for indoor Free Space Optic (FSO) networks. This transmitter will be able to provide the lighting and communication at the same time. Thanks to special solution in spectral characteristic of transmitted light it is necessary to use two LED diodes radiation sources. The light beams(More)
This article deals with few described loss which can appear in Free Space Optic (FSO) link. It is a misalignment loss which comes on by inaccurate installation of FSO heads. A calculation of this loss is based on power budget. The calculation of misalignment loss was done for professional FSO link which is installed in campus of VSB-Technical University of(More)
White LED diodes are increasingly used. Thanks their features they are also used for illumination and gradually replace the classical light bulbs and fluorescent tubes. The one of advantages of white LED diodes is their availability for the Visible Light Communication. This article deals with study of suitable placing of light sources for indoor. The aim is(More)
The influence of atmospheric environment is fundamental for Free-Space Optical link (FSO). The atmosphere can significantly degrade the communication quality of FSO up to so low received power/RSSI level that it can lead to the loss of communication. For this reason, authors used a professional weather station built on site of FSO link for measurement of(More)
In this paper, basic information about use of the RGBY (Red Green Blue Yellow) model for mobile visible light communication systems is presented. This document contains information about differences between the traditional RGB model and the RGBY model with respect to the area coverage and white light creation, since the adding of the yellow significantly(More)
Free Space Optics (FSO) is a data transmission technology using an optical beam going through the atmosphere. This communication technology has several indisputable advantages but also disadvantages. The one of the disadvantages are the thermal turbulences. This paper deals with the artificial thermal turbulences which affect the optical beam going from the(More)
The communication properties of the white Light Emitting Diodes (LED) above all depend on a phosphor decay. This article describes the measurement of rise and fall times of white light created by the blue LED and the YAG:Ce phosphors. Measured rise and fall times are compared to rise and fall time of the blue LED. We tested four kinds of phosphors which are(More)
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