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Optical fibres and their polarization effect
Klesnil, Ondřej ; Dostál, Otto (referee) ; Filka, Miloslav (advisor)
This project describes the fundamental concepts and basic theory of polarization mode dispersion (PMD) in optical fibers. There are described basic the relation between Jones vectors and Stokes vectors, rotation matrices, the definition and representation of PMD vectors, the laws of infinitesimal rotation. After the introduction the first conception with bases of polarization mode dispersion (PMD) in optical fibers, they have become an important body of knowledge basic for the design of high-capacity optical communication systems. PMD effects are linear electromagnetic propagation phenomena occurring in so-called “single-mode“fibers. Despite their name, these fibers support two modes of propagation distinguished by their polarization. Because of optical birefringence in the fiber, the two modes travel with different group velocities, and the random change of this birefringence along the fiber length results in random coupling between the modes. With current practical transmission technology the resulting PMD phenomena lead to pulse distortion and system impairments that limit the transmission capacity of the fiber. I describe different ways of measuring PMD in optical fibre, PMD compensation techniques and analyse PMD results in optical fibres.
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Methodology for the measurement of optical arterial network
Chleboun, Jan ; Dostál, Otto (referee) ; Filka, Miloslav (advisor)
There are methods to extend the transmission channel of optical transmission medium thanks to the development of telecommunications and informatics. Multiplex is a grouping of signals into a single transmission path and wave-division multiplexing is the best reason of use of the maximum fiber optic transmission capacity. The subject of this work is to determine whether a particular transmission path is suitable for such an extension of their capacity and how much. The answer is obtained by measuring the attenuation, the chromatic dispersion and the polarization mode dispersion, whose values are strictly limited and which determine next steps in the expansion of the transmission path, which is comprised by optical medium. Measurement methods determine the nature of the measured route and its current transmission capacities. Draft of the measurement methodology, which ensures the correct procedures during a possible transition to higher speeds is the output of this work. Thanks to the acquired characteristics of the BAPS (the Brno Academic Computer Network), the bit rate 40 Gb/s can be provided on this part of the network under the conditions of the introduction of certain countermeasures, particularly the exchange of a connectors on the measured optical lines. As for the back reflection lines in excess of the standard recommendation and pre-emptively on the lines with values with still agree with the return loss. Countermeasure for limiting of the chromatic and the polarization mode dispersion are do not need to stand in the way of a planned transition to a higher rate of the BAPS.
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Automatic detector of vehicle road accicents
Žurek, Jan ; Morský, Ondřej (referee) ; Dostál, Otto (advisor)
This master‘s thesis treat of car safety. It includes an introduction into already existing active and passive safety systems and briefly describes their basic principles. It also includes a description of basic principles of car electronic systems. It will acquaint us also with elementary calculations in the area of car crashing into a solid obstacle. On base of this information was developed and consequently realized development module of an automatic car accident alarm that transfers information using SMS messages to a cell phone. The message contains date, time and GPS coordinates of the accident and acceleration sensor readings in three axes.
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Optical Convertors
Chleboun, Jan ; Dostál, Otto (referee) ; Filka, Miloslav (advisor)
Optical converters are used in various types of optical networks to provide end-users of data and voice services and also allow reception of television broadcasting, which is transmitted through optical media. The current trend is the construction of FTTH networks (Fiber To The Home), which, thanks to optical fibre, have reduced the speed or capacity, as in the case with metallic networks. The proposal is the need to consider positive and negative factors associated with building of concrete network with a specified number of users and location. Each network consists of passive and active components. Passive can be used for transmission of information, therefore they are mainly elements transmission medium. Active part includes elements for sending and receiving information transmitted by optical media. Transmitters vary their technical implementation, quality and reliability. This obviously affects the price of both active and passive parts. The cost of the operation of the network are also increased with demands of control. The advantage is the efficient management, which is guaranteed by return of the cost to build a FTTH network. Optical network with a system of remote management converters is a new trend of optical communications.
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Application of GPRS module for real-time transmission of JPG files
Rusinský, Jan ; Hošek, Jiří (referee) ; Dostál, Otto (advisor)
This document describes a design procedure of interface between VGA camera and GSM/GPRS modem for displaying JPEG pictures captured by camera on website. Interface is realized by eight-bit micricontroller ATMEL with application written in C language. For picture transfer to server a TCP/IP stack is implemented into modem. The document is divided into two main parts. The first part describes architecture of the system, used components (camera, modem, microcontroller) and electronic circuit design. The second part of the document is focused on the software for the system. Firstly operating system of modem is desribed, OpenAT development environment for modem application design and WIPsoft library, which is used to implement TCP/IP stack. Next is described application for microcontroller which controlls camera and modem. Last part of this document describes server application and web interface.
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PMD - polarization mode dispersion and its effects on data transport
Trávníček, Pavel ; Dostál, Otto (referee) ; Filka, Miloslav (advisor)
My graduation thesis is concerned with the effect of polarization mode dispersion on transmitted signal by optical line. It describes external and internal causes of origination of polarization mode dispersion. On the basis of these effects there is a differential group delay (DGD). It is the time delay in meantime within individual modes. DGD results in a time extension of impulsion and limitation of maximum bit rate. This thesis contains localization methods of part of gossamer filament with increased value of PMD by POTDR method. This method is based on the principium of back dispersion and its modifications SOP a DOP. Very important chapter of this thesis is the measurement of the polarization mode dispersion. There are described methods of PMD measurement. It is the interferometric and polarimetric method and the method of state of polarization. The major part of this thesis is about the reduction of polarization mode dispersion effect. This part is divided into two parts. First part is about the methods of PMD effect reduction and the second one is about the PMD compensation. The discrepancy between these two parts is the reduction way of PMD effect on transmitted channel. The compensation use the compensation components inserted into the transmission path. By PMD reduction methods we can solve the problems from the view of changing of fibre or all cable. For better understanding of polarization mode dispersion effect there are simulated 4 optical lanes of various parameters. The simulation output is the eye diagram which provides the view at results of transmission lane. In the final part there is the evaluation of measured parameters of optical lanes simulated in a laboratory.
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Wireless optical links in LAN and MAN networks
Šporik, Jan ; Dostál, Otto (referee) ; Filka, Miloslav (advisor)
The main aim of this thesis is the design of an optical wireless link that is transmitted in free space, in the atmosphere. The thesis describes the composition of heads of the atmospheric optical link. One part of this work focuses on the issue of the spread of optical beam in the atmosphere. The facts which have a major impact on the transmission of optical radiation in free space are pointed out here as well. In this work phenomena of absorption, refraction of light, turbulence and dispersion are discussed. Wavelengths spread in the atmosphere with different decline and therefore this thesis provides an analysis of the use of wavelengths between 750 and 1600 nm depending on the meteorological visibility. It describes the basis of the design of AOS through stationary model using power balance equation. It depicts the description of the statistical model, which makes possible to determine the availability on the basis of probability. Current possibilities of AOS are in general described in this work. The practical part of the work is focused on the design of simulation model of transmitter and receiver AOS in the program Pspice. The receiver and transmitter are designed to replace transiver in the media converter. The receiver plays a key role, and therefore big part of the thesis is given to it. Receiver model is composed of a photodiode and of an transimpedance amplifier. The receiver circuit has been tested. The model of transmitter shows the principle of modulating of current, which flows in laser diode. This work does not carried the model of atmosphere, which would serve as a link between the receiver and the transmitter. The circuit of the receiver is subjected to the noise analysis. Parameter NEP and SNR is designed. Link budget is calculated for models of the receivers and the transmitters. The maximum distance of heads is set based on the requirements for a BER error rate which combine this condition. The design of the practical implementation results from the models of transmitters and receivers. Printed circuit boards are designed in EAGLE. Within the frame of this thesis no curcuit diagram is carried out.
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Effects of assembling on quality of cable systems
Konvalinka, Vladimír ; Dostál, Otto (referee) ; Filka, Miloslav (advisor)
This master´s thesis deals with questions of measuring of cabling systems. There is described the evolution of structured cabling including the rules of their installation, approval and their final measurement. The first part of this work is dedicated to the conception of structured cabling and its history which originated at the beginning of 80s when the first personal computers began to appear at the market. The necessity of mutual communication of their users caused forceful development of networks and technologies. As a result lots of single-purpose, incompatible and mutual independent cabled distributions were developed. This method of cabling was uneconomical, very demanding on service and impractical for network expansion. That’s why the universal cabled system was developed whose baseline became a twisted pair. Characteristics of structured cablings are designed in order it could be possible to transmit whole rang of applications through them. Metallic cables and nowadays also optical cables are used for their installation. The cabling system consists of lots of other items among them we can rank items active and stable. It’s necessary to scale lots of criteria which involve the quality of data transmission in this network. The measurement is done by the devices which comply with basic requirements determined by the standards according to technology. There are described the rules and proper processes of installing cabling systems, which should be followed while installations. At the end of my thesis there are mentioned the results of the measurements on simulation segments of cabling system which serve as completion certificates between an installation company and a consumer.
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Polarization mode dispersion
Turský, Aleš ; Dostál, Otto (referee) ; Filka, Miloslav (advisor)
The work deals with dispersive effects of single mode fibers. We learn about the chromatic dispersion, the main attention is paid to the Polarization Mode Dispersion. We clarify the root cause origin of the Polarization Mode Dispersion describing parameters and its effect on transmitted data. Further on, the works dedicates to measure methods of the Polarization Mode Dispersion which is the interferometric method or the POTDR method. We explain the ways of the PMD removal at contemporary optic routes and options of PMD compensation by using compensators of various types. There is also mentioned the possibility of profiting from the soliton transmission. The last chapter deals with measuring of a real optic route. It includes measured data and its evaluation due to the ITU-T demands.
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