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The Optical Fibre Dispersion Effects on Multiplex Transmission Systems
Kyselák, Martin ; Filka, Miloslav (advisor)
This doctoral thesis deals with present trend to turn up the bit rate of the optical fibres making use of wavelenght multiplex systems. There are new theoretical and practical problems caused by the new technologies. Except the known modal dispersion there exist problems caused by chromatical and polarization mode dispersion. In the opening of the thesis the known effects, which influence the payload signal, are introduced. The polarization mode dispersion has the main attention. Within the scope of this thesis there has been programmed the statistical calculator which can analyses the measured values of differential group delay by Monte Carlo calculation. Next meaningful output is the designating application of the optical routes. It is possible to mathematicaly unambiguously define the polarization mode dispersion by Jones, Stokes and Poynting vectors. This complicated calculations are mechanized and in the simulation application make possible to simulate the signification of the PMD influence at different input parameters. The thesis includes the study of the PMD modulation format impact with the results of simulations and confrontation with other scientists results. The significant output are the final practical results examinations, which can be implemented thanks to the possibility of using the FTB-5500B measuring device.
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Modulator and demodulator for microwave link
Martinec, Matěj ; Frydrych, Jiří (referee) ; Záplata, Filip (advisor)
This work is dealing with the design of intermediate part of transmitter and reciever that use digital BPSK and QPSK modulations for microwave link that works in 24 – 26 GHz bands. Besides choosing the suitable modulator and demodulator there was need to provide proper connection of this part with transceiver Nortel CTR26-01M. Input and output of this intermediate part was take out to baseband, where was need to ensure the transfer of diferential inputs of modulator and demodulator to symetric leading for reason of data communication with PC, for which was created the algorithms to provide transmitting and receiving data. Complete structure controlled by the microcontroller has been enliven and furthemore there was created the measurement of chosen parameteres.
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Computer modelling of data transfer over power lines
Křivka, Petr ; Mlýnek, Petr (referee) ; Mišurec, Jiří (advisor)
The master‘s thesis is focused on data transfer over power lines. The influence of connected devices on data signal is studied. In this thesis, you can find the descriptions of PLC technology characteristics, sources of signal interruption and, mainly, the method of modelling the PLC channels as a multipath signal propagation environment is thoroughly discussed. There are models of PLC channels using this method projected in Simulink. The analysis of the influence of connected devices to bit error rate of a signal is processed. The devices are modelled by connected impedance.
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Power line parameters
Kavan, Pavel ; Krajsa, Ondřej (referee) ; Mlýnek, Petr (advisor)
At the beginning is diploma thesis focused on a distribute power line parameters measurement and examination changes of this parameters depending on using of various power line cables. On the basis of measurements is made a transmission channel in Matlab & Simulink, where are executed simulations with power transmission line. The simulated power line is based on measured distribute parameters or physical proportions of cabels. By changing different parts of simulated communication channel is a symbol error rate expressed on the lenght of transmission line.
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Modelling of PLC system to ensure the reliability of communication
Procházka, Vít ; Mišurec, Jiří (referee) ; Mlýnek, Petr (advisor)
The master´s thesis is focussed on principles and characteristics of Powerline Communications (PLC), practical usage possibilities and advantages and disadvantage of it. There are described mudulations and a channel encoding which are in PLC used. The main part of the thesis deals with a design of a channel as transfer function through the use of two methods, an echo model and the ABCD matrix. After finishing of the design of transfer function the model of communication was created in the Matlab-Simulink program. There were used the narrowband modulations in the model and analyzed the bit error rate of the tranfer data. In the end all results were treated graphically and evaluated.
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Design of Graphic Interface for Calculation of Differential Group Delay
Vohralík, Jan ; Křivánek, Vítězslav (referee) ; Kyselák, Martin (advisor)
The Bachelor's thesis is aimed to the problems regarding Polarization mode dispersion in optical fibre. Polarization mode disperzion limits the bandwidth of high speed comunication system. It cases a differential group delay between different polarizatins. If the delay is too high than the bits overlap and a bit error rate is increased. The work include description of polarization in Jones space and Stokem space. For description of Polarization mode disperzion is used PMD vector. I demonstrate influence of differential group delay in optical fibre at special grafic program develop in C# language.
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The impact of polarization mode dispersion on error-rate of optical fibre link
Dorociak, Petr ; Křivánek, Vítězslav (referee) ; Kyselák, Martin (advisor)
Master’s thesis engages in the impact of polarization mode dispersion on optical communication system. Polarization mode dispersion is mathematically described by Stoke’s and Jone’s space and ensure the theoretic causes of the rise of polarization mode dispersion that are divided on the external and internal effects. On the basis of these effects grow up a differential group delay (DGD) which makes causes that individual polarization modes have between them a time delay and limitation of maximum bit rate. Then master´s thesis analyses the influence of the polarization mode dispersion on the pulse enlargement and on the modulation signal. In this work, there are described the most applicated optical modulation formats. Polarization mode dispersion has also influence on the bit error rate of optical fibre link and closing of eye diagram too. Eye diagram is used to view the transmission characteristics and diagnoses the channel errors. Eye diagram is connected with the definitions as a bit error rate (BER) and signal-to-noise ratio (SNR) that are explained in this work too. Following the gained experiences it was designed an useful graphic interface to display the effect of the polarization mode dispersion on the transmitted signal. Realization of the graphic interface is created in the program MATLAB. In Matlab-Simulink are created six models according to the kind of modulations with characteristic AWGN (Additive White Gaussian Noise) channel. Program was tested for a typical values. In all calculations it is counted only with the losses that are caused by the polarization mode dispersion. It is not calculated with the losses that are caused by a chromatic dispersion and attenuation. At the end of this work are evaluated all types of modulation formats depending on the polarization mode dispersion, optical fibre length, price and complexity of the realization. Atteined results of my master’s thesis are compared with two foreign articles.
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Protection of data transmission against long error bursts
Malach, Roman ; Lambertová, Petra (referee) ; Němec, Karel (advisor)
This Master´s thesis discuses the protection of data transmission against long error bursts. The data is transmited throught the channel with defined error rate. Parameters of the channel are error-free interval 2000 bits and length of burst error 250 bits. One of the aims of this work is to make a set of possible methods for the realization of a system for data correction. The basic selection is made from most known codes. These codes are divided into several categories and then the best one is chosen for higher selection. Of course interleaving is used too. Only one code from each category can pass on to the higher level of the best code selection. At the end the codes are compared and the best three are simulated using the Matlab program to check correct function. From these three options, one is chosen as optimal regarding practical realization. Two options exist, hardware or software realization. The second one would seem more useful. The real codec is created in validator language C. Nowadays, considering language C and from a computer architecture point of view the 8 bits size of element unit is convenient. That´s why the code RS(255, 191), which works with 8 bits symbols, is optimal. In the next step the codec of this code is created containing the coder and decoder of the code above. The simulation of error channel is ensured by last program. Finally the results are presented using several examples.
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Lean Six Sigma in Decreasing the Error Rate of Proposal Form Filling
Albert, Michal ; Plášková, Alena (advisor) ; Žák, Daniel (referee)
This thesis is focused on the proposal form filling error rate in life insurance. The theoretical part of the thesis describes main aspects of the methodology Lean Six Sigma, which will be used to decrease high error rate. Lean Six Sigma is widely used in today's companies to improve business processes by increasing their sigma. The methodology is an integration of two separate approaches, both invented in the beginning of the 20th century. The aim of the integration is to bring together the best of both of them. The practical part of the thesis shows how the seemingly separed approaches Lean and Six Sigma can work together. Lean was used to improve the process for insurance company's sales force, and Six Sigma was then applied to decrease the error rate of the forms. Both of the improvements were successfully implemented in the company and led to a desired outcome.
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