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Cell - Phone Effects on Human Health
Pieniažek, Ireneusz ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
This bachelor’s thesis is dealing with the influence of cell phones on man. First part is focused on the introduction to the problems of cell phone communication. There are described the frequencies and wave lengths, which the cell phones use. Here is also described the principle of cell phones functioning. Second part is devoted to influence of the cell phones on the human body. It is discussing the electromagnetic compatibility of the biological systems and describing the electromagnetic field occurring in cell phone communications. There are also described the thermal effects of the cell phones and this chapter further discusses the hypothesis about the non-thermal effects of the cell phones. There is a description of mechanism of influence of radio waves. This part also describes the possible health hazards resulting from the use of cell phones and the problem of relationship between the occurrence of cancer and the use of cell phones. There are mentioned other ecological problems connected with cell telephony. Third part is focused on the SAR measurement (specific absorption rate) of the cell phone. Here we can find the definition of SAR. It describes the tested apparatuses, the procedure of measurement and measured values for GSM 900, GSM 1800 and W-CDMA 2000 standards. Tested apparatus in this case is Samsung SGH-Z140V. We can find here technical engineering solutions, which are aimed to minimize the specific absorbing power absorbed by human body during the use of apparatus.
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Optical cableless transmission
Němec, Filip ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
This diploma thesis first handles the general issues concerning free space optics in the~atmosphere. The aim is to design and implementation of optical wireless equipment, which would serve in the laboratories of optical networks. Ronja was used as the basis for a~wireless link, which is already widespread in the world. Students will work with the device, which they may come into contact in the future. It consists several separate modules: transmitter, receiver and inteface. Each module have a separate chapter describing the~functional blocks and circuit realization. Ronja was adjusted for the needs of~laboratory tasks, where additional voltmeters measures received signal strength (RSSI) at~both ends of the link. Measuring device provides adjustment of power the transmitting LED via~computer, measures and sends RSSI values to a PC via~USB or RS232, turn off Ronja with computer. For targeting the pipes of Ronja was developed the mechanical design. In the last part of thesis the device was undergone a series of tests.
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Optical amplifier in laboratory practice
Šustr, Pavel ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
The aim of this thesis is to introduce to reader the application and use of optical EDFA amplifiers in optical transmission and to show wiring and practical test, including measurements on amplifier. The aim of this thesis is to propose the use of optical amplifier in laboratory practice for subject Optical networks. The thesis briefly introduces the problems of data transmissions through optical fibers with a focus on the use of optical amplifiers. The basic characteristic of optical transmission paths and the reasons for the use of optical amplifiers are described here. One entire chapter is devoted to distinction of optical amplifiers. Amplifiers can be divided according to location in the transmission path to the booster, in-line and pre-amplifiers and according to the used of amplifying technology to optical amplifiers with subsidies, semiconductor optical amplifiers and Raman optical amplifiers. The factors affecting the efficiency of optical amplifiers, such as noise and the level of saturated power are mentioned here too. The different types of optical amplifiers from the two producers are also described. From these amplifiers was chosen EDFA CzechLight Amplifier from Optokon to be used for the laboratory exercise in the subject of Optical networks. The use of EDFA optical amplifiers in optical transmission lines is mentioned here too. These amplifiers can be used in telecommunications transmission systems and for data transmission over long distances. They will find use in WDM transmission systems and cable TV distribution through the optical fiber to the end users. Practical measurements were performed on optical amplifier CLA-PB01F. In the transmission route was located attenuator and the dependence of output power to input signal power was measured. The amplification course was linear in the range of input values provided by the manufacturer. Laboratory exercise for the subject of Optical networks is aimed at preacquaintance of students with problems EDFA optical amplifiers and practical measurements with the optical amplifier CLA-PB01F. Students acquire basic theoretical knowledge of the issue and verify the functionality of optical amplifiers on a specific exercise. This work is destined for all who wish to get basic knowledge of optical amplifiers, their characteristics and possibilities of their use in optical transmission lines.
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The transmission speed enhancement techniques in TKR
Šťovíček, Petr ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
The purpose of this work is to assess and propose possible methods for increasing the transmission speed of the cable television distribution, concretely the UPC network in Brno. The first part of work collectively processes general knowledge and gives the reader into the issue. After that follows an analysis of TV cable networks UPC in Brno, especially view of data transmission. After familiarization with the physical aspect of the network is described data communications itself, including standard DOCSIS, respectively EuroDOCSIS. Particular attention is paid to factors that have effect on data transmission and speed. Benefit is the calculation of dividing ratio in different parts of the network and compared with the real load. As far as possible in the given work results of measurements with regard to the quality of the network. The last part is about how to increase speeds. Perspective solution is mainly a technology which is based on standard EuroDOCSIS 3.0, which introduces the concatenation of individual channels. Result of made tests of first cable modem EuroDOCSIS 3.0 confirms the very high speeds and currently preparedness for other major step in so long development of TV cable network.
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Effects of mechanical doings on optical data transport
Tihlařík, Tomáš ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
This master´s thesis deals with of human factor impact on optical fibers manipulation. It describes types and methods used for splicing and placing optical fibers and optical cables. These methods are specified in the chapters; their application in different environments and conditions is accentuated. This paper presents splicing optical fibers. It emphasizes problems which can occur if proper procedures aren´t kept or if improper device is used. In the thesis there is the chapter dealing with problems which can arise during splicing optical fibers - these negative influences are evaluated with educational equipments EF-970-01 PLASTIC by the company MIKROKOM, s.r.o. Another aim of the work is to describe mechanical optical fiber splice 3MTM FibrlokTM. This kind of device was lent for testing optical fibers multiple splicing. It was tested under extreme conditions. Statistically processed values of insertion loss and splice reflectance, measured by OTDR are the results of the test. Comparing measured values, technical report ones, regarding for usage in practice, there is a possibility of 75 multiple reusing of the mechanical optical fiber splice. The prediction of magnitude insertion loss, calculated for thousands splice cycles follows. The next part of the work deals with fusion splices and contains comparison of splices made with two cleavers: CORNING LWL-TRENNGERAT S46999-M9-D12 and the later model - Fitel S325A cleaver. The result is that older S46999-M9-D12 model gained lower attenuation. The results of both previous measurements are influenced by human factor. It appears at mechanical optical fiber splices as growing fluctuate of insertion losses and as the unequal attenuation fusion splices at tested cleavers.
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FTTB Network Design
Reichert, Pavel ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
The purpose of this master’s thesis is to explain the issues of the FTTx network design. The main idea of this work is to describe to readers the methods of the designing the optical access networks. Especially we will speak about the building technologies and different topologies used in a practice. The different technologies of optical access networks’ building and various parameters, which are necessary to take into account in the designing of these networks, will be introduced. In the theoretical part, methods of measurement, which are like the needed part of each optical access networks’ building, will be described. Two purposes of the FTTB networks with all proprieties will be made and offered. One purpose will be solved by Point to Point topology and the second purpose will be solved by Point to Multipoint topology. Following the confrontation one of these purposes will be chosen and realized. By ITU recommendation, measurements will be performed on the built optical trace. The final protocols will be elaborated from these measurements. The built trace with all final reports will be prepared for assignment to the subscriber.
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Optical Amplifiers
Mlejnek, Zbyněk ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
Optical amplifiers has sparked a revolution in the telecommunications industry during th last ten years. Optical amplifiers are devices that amplifies an optical signal directly, without the need to first convert it to an electrical signal. Its ability to provide low-noise amplification over a range of wavelengths, fortuitously correspoding to the low-loss of silica fiber, has made optical networks economically attractive
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Application of ArcGIS Program in Telecommunication Networks
Štohanzl, Pavel ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
This thesis deals with the issues of locating and marking both metalic and optical transmission network. The choice of an appropriate program for creation and management of map document is discussed. In the following chapter some necessary adjustments to the ArcGIS ArcView program are made so that it is applicable to the field of telecommunication networks. The last chapter addresses the design of documentation options in optical transmission network. For metalic cables the possibilities of attaching transmitter to a cable and locating the induced magnetic field is covered. Among the methods for finding optical cables we list ways of locating through the use of markers, GPS location and added metalic conductors. Fundamentals of markers and their types are thoroughly analysed. In the chapter on GPS we examine how this system works and evaluate its accuracy. The next chapter enumerates requirements that a program should meet. We analyse properties of considered programs and evaluate them with respect to these requirements. For a chosen program the possibilities of enriching it with selected map document are discussed. For these map document, information about their applicability and source is presented. We also quote the cost for these maps wherever possible. The last chapter treats ways of documenting optical networks.
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Software solution of documentation of buried cables
Zavadil, Pavel ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
The content of this work is focused on the production of software solution of documentation and on the work procedure leading to the production of software documentation for telecommunication network and mostly for its optical part. As the production of metallic and optical part is from the global point of view the same, only a change of attributes will take place because of the different characteristics of both media. The basis of every computer documentation is software, that is why we need to pay special attention to its choice and we should firstly make a list of requirements, which should the software fulfil. The essential requirement is the connection of database and graphical parts of the documentation. Once we have chosen the software with the requested requirements, we can approach the proposal itself. For the maximal accuracy of the input data we use only geodetically focused data. For the production of a database work is crucial the cooperation of all the users so that every future user has for him necessary data at his disposal. All the theoretical approaches are examined in the last part of this work on the project produced for a company SELF servis which requires the production of software documentation of its network. Documentation is based on the software ArcGIS, which is not aimed directly at the telecommunication purposes, but which enables the connection of graphical and database data and fulfils all the requirements made by SELF servis company. Among these requirements belong the possibility of usage of different types of bottom maps, the possibility of connection of database with the external SQL database and also restrictions to data access.
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Effect of optical connectors quality on transmission
Bernkopf, Miroslav ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
This diploma thesis deals with optic fiber connectors and their influence on transmissions realized via fiber optics. Optical fibers and lightguides play the key role in telecommunications because of constant demands of higher bandwidth and data rates. Original metalic wires do not meet market requirements and so the fiber optics are more and more being used. There are various types of fibers and there are also many ways of connections. This work deals with demountable way of connection – optical connectors, which have the biggest influence on a total attenuation and route length. Connector has to meet various requirements such as cleannes, quality, mechanical construction and ferrule polishing.
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