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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 a uniform light distribution and thereby...
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 able to create a white light. The phosphors...
With deployment and continuous development of optical routes, the issues concerning the thermal loading of erbium-doped optical fibres become more and more relevant. As we were able to see a significant expansion of optical communication systems in the recent years, it was also necessary to find ways for bridging longer distances between individual points of the optical route. Modern optical telecommunication...
In this article the composite author dealt with measurement possibilities of polarization states of light source emitting 1550 nm which was affected by atmospherically transmission environment in special acrylate box 2.5 m long. The Polarimeter Thorlabs TXP 5004 and the External Sensor Head PAN5710IR3 measured the changes of polarization parameters, ellipticity and azimuth, defining placement on the...
This article aims for meeting with influences of the atmosphere on real professional Free-Space Optical (FSO) link. Atmospheric effects could cause a degradation of quality of FSO communication and of received optical beam in shape of decreasing of optical power value through parameter RSSI (Received Signal Strength Indicator). Finally, this could even lead to communication loss. The article focuses...
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 commercial FSO head. The new against articles...
This article presents the concept of deploying Software Defined Radio (SDR) for laser beam modulation in Optical Wireless Communication (OWC). To achieve modulation and demodulation of the beam generated by Laser Diodes (LDs). SDR is used to provide a sophisticated and flexible possibility of readjustment without deeper intervention into the electronics of the OWC connection. To make conclusions regarding...
This article presents new insights in the research of VLC communication transmitter based on multimode optical fibres. Optical transmitters are formed by a different number of optical fibres. These fibres illuminate the defined surface area in the form of the 1/8 of the sphere, which simulates the room corner. The aim of this article is to point to possible new trends in the field of research such...
This article explores the influence of the concentrated carbon dioxide (CO2) gas on the different Phase Shift Keying (PSK) modulations used for Optical Wireless Communication (OWC) links. In this work, the OWC consisted of a laser diode, a photodetector, and a transmission medium. The Universal Software Radio Peripheral (USRP) unit created and evaluated the PSK modulations. This unit modulated the...
Visible Light Communication (VLC) represents a progressively developing communications technology. This technology uses optical radiation in the visible range in order to illuminate a given area also for the communication purposes (download). One of the conditions of using the technology is the construction of a VLC modulator. The use of the technology Bias-T proves to be a highly efficient concept...
This article describes the design and implementation of the software simulator for modelling interferences, which occur in real transmission channels. This simulator allows the modelling of wireless fading channels (e.g. additive white Gaussian noise — AWGN, Rician fading channel and Rayleigh fading channel) and also RF impairments (e.g. phase noise, DC offset, quadrature skew, and IQ gain imbalance)...
In this article the author team dealt with possibilities of using different types of modulation formats (NRZ, RZ (33%, 50%, CSRZ 67%, CRZ), DB, RZ-DPSK, NRZ-DPSK) for WDM-PON network with a view to point to merit of individual modulation types regarding to bit rate change and link distance. The individual modulation formats are then evaluated with perspective to limits of access networks based on...
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 Ostrava. Results showed that a small misalignment...
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 affects system properties in many ways. There...
This article deals with problem of thermal turbulence effects created by direct heaters on optical link which used OOK modulation for communication. For the purpose of uniform conditions of thermal turbulences with speed of 3.5 m·s1 and temperature 48 °C the special laboratory box was made. On the transmitting side the bit rate (0–160 Mbps) of optical link was changed and on the receiving side was...
This paper is aimed at problematic of illegal service connections localization and contamination of sewage water in sewer system using sophisticated method utilizing fiber-optic distributed temperature sensing. The article objective is finding of proper methodology of localization of illegal service connections into the sewer network.
This article is dealing with properties overview of thermal turbulences influencing optical beam of atmospheric optical link. The team of authors was focused on simulation of thermal turbulences caused by hotplate heater that heated water up to boiling point. Thermal turbulences were fanned by three high-speed ventilators and were kept in the wooden box to achieve stable conditions with the respect...
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 of these LED diodes have to be spatially...
This article is focused on the atmospheric turbulences and their effect on optical beam. The Free Space Optics link with atmospheric turbulences was created in software OptiSystem. The results given by software are compared with Andrews's method. Free Space Optics link worked at wavelengths 850 nm and 1550 nm.
This article describes an intensity distribution of optical beam in the far field. In free space communication laser transmitters, optical lenses and other components are used. When an optical beam impacts optical lens, the diffraction can appear at the edge of lens. A laser transmitted optical beam whose intensity distribution was Gaussian. This beam was aimed at the circular apertures of different...
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