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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Encoding of multi-track (d,k) modulation codes.

Orcutt, Edward Kerry. January 1992 (has links)
Multi-track run-length-limited (d,k) modulation codes were recently introduced as a method to increase storage densities in magnetic and optical recording systems. These codes are a generalization of the usual run-length-limited (d,k) codes and provide for increased storage density by relaxing the k-constraint and encoding multiple tracks in parallel. This dissertation focuses on methods of constructing such codes. Two methods are presented. The first uses state-splitting to construct multi-track (d,k) trellis codes. An example is presented in which a (1,3) trellis code is constructed having a code rate of R = 2/3. The second method results in the construction of multi-track (d,k) block codes which are implemented via an enumeration scheme based on the trellis description of the (d,k) constraints. This implementation results in memory requirements which increase only linearly with block length as opposed to the exponential increases arising from look-up table implementations. Additionally, a new class of multi-track codes referred to as redundant multi-track (d,k) codes, is introduced. These redundant codes, unlike the original multi-track (d,k) codes which are completely intolerant of faulty tracks, allow for r faulty tracks while maintaining synchronization.
22

Characterization of NI-USRP System

Fu, Xubo January 2014 (has links)
Nowadays the rapid developments of wireless communication technologies there are more and more ways to look into the RF measurements and designs in detail such as Universal Software Radio Peripheral(USRP) from LabVIEW, Advance Design System(ADS),etc.Moreover a lack of measurements what compared with different digital modulation schemes is becoming a problem. In this thesis by building the simulations of communication system in NI-USRP system and measuring the results then compare with the different PSK system in order to give a deeper insight of this new software of USRP from LabVIEW. and in the end analyze bit error rate varus signal to noise ratio from the PSK system. To get the characterizations of NI-USRP system the first step is to build multiple simulations such as FM receiver, PSK wireless communication systems. By performing the FM receiver is to analyze the quality of the receiving and baseband FM signal. And from the simulation of different PSK communications through the analysis of the performance of BPSK,QPSK,OQPSK and compared with bit error rate it could give an insight of characterization of NI-USRP system and in the end the conclusions give in which kind of prototype or simulation that suit the best of NI-USRP system.
23

Sintonizador-demodulador para o sistema brasileiro de TV digital. / Front-end of the Brazilian Digital TV system.

Bedicks Junior, Gunnar 30 June 2008 (has links)
O sintonizador-demodulador de RF, também chamado de Front End, é definido de uma forma geral como sendo o conjunto ou módulo que está entre a antena e o sistema digital. Para um receptor isto inclui todos os filtros, amplificadores de baixo ruído, misturadores e demoduladores, necessários para processar o sinal modulado recebido na antena, demodulá-lo e entregá-lo em um fluxo de bits (Transport Stream) para o sistema digital de decodificação, também conhecido com Back End. Por esta razão o sintonizador-demodulador é muitas vezes chamado de conversor RF para TS (Rádio Freqüência para Transport Stream). Por ser o primeiro bloco, o Front End é a parte mais importante, e também a mais crítica de qualquer receptor contribuindo muito para o seu bom ou mau desempenho. Esta tese investigou os problemas existentes e que degradam a qualidade do sinal nas transmissões de TV analógica; os testes realizados pelo laboratório de TV Digital do Mackenzie comparando os padrões de transmissão dos sistemas de TV Digital, ATSC, DVB-T e ISDB-T; o modelo proposto e adotado pelo Sistema Brasileiro de TV Digital; e propôs um modelo de sintonizador-demodulador para o SBTVD, que atendesse as necessidades do sistema com robustez e flexibilidade. O sintonizador-demodulador foi desenvolvido, projetado, montado e testado no laboratório e no campo para avaliar a sua eficiência. / The RF front end is generally defined as everything between the antenna and the digital baseband system. For a receiver, it includes all the filters, low-noise amplifiers (LNAs), down-conversion mixers and demodulator needed to process the modulated signals received at the antenna into signals suitable for input into the baseband analog-to-digital converter (ADC), demodulate it and feed with a Transport Stream the Back End part of the system to decode the signal. For this reason, the RF front end is often called the RF-to-TS portion of a receiver. It turns out that this is the most important and critical part of the whole receiver aiming for its good or bad performance. This thesis researched the existing problems that degenerate the analog TV transmission quality; the digital TV tests realized by Mackenzie DTV laboratory comparing the digital TV transmission standards, ATSC, DVB-T and ISDB-T; the proposed and adopted model for the Brazilian Digital TV System; and a proposal of a Front End for the SBTVD that meets the requirements of the system with robustness and flexibility. The Front End was designed, assembled and tested in the DTV laboratory and in the field.
24

Um estudo comparativo entre os sistemas OFDM e SCCP. / A comparative study between the OFDM and SCCP systems.

Paula, Amanda Souza de 21 January 2010 (has links)
Este trabalho trata da comparação entre os sistemas OFDM (orthogonal frequency division multiplexing) e SCCP (single carrier with cyclic prefix). Tais sistemas são analisados em função da ordem da modulação, da sensibilidade em relação à taxa de codificação de canal e do tipo de entrelaçamento utilizado. A comparação é efetuada através da adoção de um arcabouço que provê uma abordagem universal para o tratamento de ambos os sistemas. São obtidos resultados teóricos, explorando características de convexidade de funções, e resultados a partir de simulação Monte Carlo. Os sistemas são comparados, principalmente, em termos de BER (bit-error rate). Entretanto, também são realizadas comparações em termos de probabilidade de outage por cutoff rate e da SNR (signal to noise ratio) efetiva na saída do equalizador. Finalmente, os sistemas ainda são avaliados quanto à sensibilidade a erros de estimação de canal. / This work deals with the comparison between the OFDM (orthogonal frequency division multiplexing) and SCCP (single carrier with cyclic prefix). These systems are analyzed as a function of the modulation order, the sensitiveness to the channel coding rate and to the interleaver configuration. The comparison is accomplished by means of a system model that leads to an universal framework to both analyzed systems. Theoretical results are obtained exploring convexity properties of functions. In addition, some results provided by Monte Carlo simulation are also presented to complement the analysis. The systems are compared mainly in terms of the BER (bit-error rate). Moreover, comparisons in terms of outage probability obtained by cutoff rate and in terms of the effective SNR (signal to noise ratio) at the equalizer output are also provided. Finally, the systems will be compared when channel estimation error are presented at the receiver.
25

Um estudo comparativo entre os sistemas OFDM e SCCP. / A comparative study between the OFDM and SCCP systems.

Amanda Souza de Paula 21 January 2010 (has links)
Este trabalho trata da comparação entre os sistemas OFDM (orthogonal frequency division multiplexing) e SCCP (single carrier with cyclic prefix). Tais sistemas são analisados em função da ordem da modulação, da sensibilidade em relação à taxa de codificação de canal e do tipo de entrelaçamento utilizado. A comparação é efetuada através da adoção de um arcabouço que provê uma abordagem universal para o tratamento de ambos os sistemas. São obtidos resultados teóricos, explorando características de convexidade de funções, e resultados a partir de simulação Monte Carlo. Os sistemas são comparados, principalmente, em termos de BER (bit-error rate). Entretanto, também são realizadas comparações em termos de probabilidade de outage por cutoff rate e da SNR (signal to noise ratio) efetiva na saída do equalizador. Finalmente, os sistemas ainda são avaliados quanto à sensibilidade a erros de estimação de canal. / This work deals with the comparison between the OFDM (orthogonal frequency division multiplexing) and SCCP (single carrier with cyclic prefix). These systems are analyzed as a function of the modulation order, the sensitiveness to the channel coding rate and to the interleaver configuration. The comparison is accomplished by means of a system model that leads to an universal framework to both analyzed systems. Theoretical results are obtained exploring convexity properties of functions. In addition, some results provided by Monte Carlo simulation are also presented to complement the analysis. The systems are compared mainly in terms of the BER (bit-error rate). Moreover, comparisons in terms of outage probability obtained by cutoff rate and in terms of the effective SNR (signal to noise ratio) at the equalizer output are also provided. Finally, the systems will be compared when channel estimation error are presented at the receiver.
26

Sintonizador-demodulador para o sistema brasileiro de TV digital. / Front-end of the Brazilian Digital TV system.

Gunnar Bedicks Junior 30 June 2008 (has links)
O sintonizador-demodulador de RF, também chamado de Front End, é definido de uma forma geral como sendo o conjunto ou módulo que está entre a antena e o sistema digital. Para um receptor isto inclui todos os filtros, amplificadores de baixo ruído, misturadores e demoduladores, necessários para processar o sinal modulado recebido na antena, demodulá-lo e entregá-lo em um fluxo de bits (Transport Stream) para o sistema digital de decodificação, também conhecido com Back End. Por esta razão o sintonizador-demodulador é muitas vezes chamado de conversor RF para TS (Rádio Freqüência para Transport Stream). Por ser o primeiro bloco, o Front End é a parte mais importante, e também a mais crítica de qualquer receptor contribuindo muito para o seu bom ou mau desempenho. Esta tese investigou os problemas existentes e que degradam a qualidade do sinal nas transmissões de TV analógica; os testes realizados pelo laboratório de TV Digital do Mackenzie comparando os padrões de transmissão dos sistemas de TV Digital, ATSC, DVB-T e ISDB-T; o modelo proposto e adotado pelo Sistema Brasileiro de TV Digital; e propôs um modelo de sintonizador-demodulador para o SBTVD, que atendesse as necessidades do sistema com robustez e flexibilidade. O sintonizador-demodulador foi desenvolvido, projetado, montado e testado no laboratório e no campo para avaliar a sua eficiência. / The RF front end is generally defined as everything between the antenna and the digital baseband system. For a receiver, it includes all the filters, low-noise amplifiers (LNAs), down-conversion mixers and demodulator needed to process the modulated signals received at the antenna into signals suitable for input into the baseband analog-to-digital converter (ADC), demodulate it and feed with a Transport Stream the Back End part of the system to decode the signal. For this reason, the RF front end is often called the RF-to-TS portion of a receiver. It turns out that this is the most important and critical part of the whole receiver aiming for its good or bad performance. This thesis researched the existing problems that degenerate the analog TV transmission quality; the digital TV tests realized by Mackenzie DTV laboratory comparing the digital TV transmission standards, ATSC, DVB-T and ISDB-T; the proposed and adopted model for the Brazilian Digital TV System; and a proposal of a Front End for the SBTVD that meets the requirements of the system with robustness and flexibility. The Front End was designed, assembled and tested in the DTV laboratory and in the field.
27

Trellis coded, adaptive rate hybrid-ARQ protocols over AWGN channels and slowly fading rician channels

Rasmussen, Lars Kildehoj 08 1900 (has links)
No description available.
28

Comparative performance of forward error correction using diversity in indoor mobile radio communications /

Munodawafa, Jacob. Unknown Date (has links)
Thesis (MEng (Research))--University of South Australia, 1993
29

Coding for reduced spectral regrowth on nonlinear channels /

Morrison, Ian Stuart. Unknown Date (has links)
Thesis (PhD)--University of South Australia, 1996
30

Performance and distance spectrum calculation of TCM over ISI channels

Nam Van Tran Unknown Date (has links)
Thesis (MEng) -- University of South Australia, 1998

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