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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.
51

Synchronization in all-digital QAM receivers

Pelet, Eric R. 30 April 2009
The recent advance in Field Programmable Gate Array (FPGA) technology has been largely embraced by the communication industry, which views this technology as an effective and economical alternative to the design of Application Specific Integrated Circuits (ASICs). The primary reasons for switching to FPGAs are lower development and non-recurring engineering costs, the flexibility to design to a preliminary standard and adapt the design as the standard evolves, as well as the option of performing software updates in the field.<p> A sector with strong interest in FPGAs is the coaxial cable TV/Internet distribution industry. The creation of soft preliminary standards by the standards organization governing the industry has been the main catalyst for the massive adoption of FPGAs by small to medium size companies, which see this technology as an opportunity to compete in this open market.<p> Both the circuit speed and the economy of FPGA technology depend upon using algorithms that map efficiently into its fabric. Often it is prudent to sacrifice performance to improve either clock speed or economy when developing with FPGAs. The purpose of this research is to both revise and devise synchronization algorithms / structures for cable digital receivers that are to be implemented in FPGA. <p> The main communication scheme used by the coaxial cable distribution industry is digital Quadrature Amplitude Modulation (QAM). The problem of synchronizing to the QAM signal in the receiver is not a new topic and several synchronization-related circuits, which were devised with ASICs implementation in mind, can be found in the open literature. Of interest in this thesis is the non-data-aided digital timing synchronizer that was proposed by D'Andrea to recover timing with no knowledge of the transmitted data. Accurate timing estimation was achieved by reshaping the received signal with a prefilter prior to estimating the timing. <p> A problem with D'Andrea's synchronizer is that the prefilter for reshaping the signal is a relatively long Finite Impulse Response (FIR) filter, whose implementation requires a large number of multipliers. This may not have been an issue with ASICs in as much as the number of hardwired multipliers on a chip is not limited as it is in an FPGA chip. One contribution in this research is to propose an alternative to D'Andrea's synchronizer by replacing the long FIR filter with two single-pole Infinite Impulse Response (IIR) filters that are directly placed inside the timing recovery loop. This novel architecture, which drastically reduces the number of multipliers, is well suited for FPGA implementation.<p> Non-data-aided feedforward synchronizers, which use the same prefilter as D'Andrea's synchronizer, have been receiving significant attention in recent years. Detailed performance analysis for these synchronizers can be found in the open literature. These synchronizers have the advantage of using a feedfordward structure rather than a feedback structure, as it is the case in D'Andrea's synchronizer, to estimate the timing. While D'Andrea's synchronizer has an advantage in performance over a non-data-aided feedforward synchronizer, this has not been reported in the literature. In this thesis a second contribution consists of thoroughly analyzing the steady state timing jitter in D'Andrea synchronizer by deriving a closed-form expression for the noise power spectrum and a simple equation to estimate the timing jitter variance. <p> A third contribution is a novel low-complexity and fast acquisition coherent detector for the detection of Quadrature Phase Shift Keying (QPSK) (i.e., 4-QAM) symbols. This detector performs carrier phase synchronization much faster than a conventional coherent detector. The acquisition time is comparable to that of a differential detector. The fast acquisition comes at the expense of phase jitter, and the end result is a 1 dB performance loss over theoretical coherent detection. This detector can be used in place of the differential detector with no economic penalty. Doing so yields a performance advantage of about 2 dB over differential detection.
52

Live Demonstration of Mismatch Compensation for Time-Interleaved ADCs

Nilsson, Johan, Rothin, Mikael January 2012 (has links)
The purpose of this thesis is to demonstrate the effects of mismatch errors that occur in time-interleaved analog-to-digital converters (TI-ADC) and how these are compensated for by proprietary methods from Signal Processing Devices Sweden AB. This will be demonstrated by two different implementations, both based on the combined digitizer/generator SDR14. These demonstrations shall be done in a way that is easy to grasp for people with limited knowledge in signal processing. The first implementation is an analog video demo where an analog video signal is sampled by such an TI-ADC in the SDR14, and then converted back to analog and displayed with the help of a TV tuner. The mismatch compensation can be turned on and off and the difference on the resulting video image is clearly visible. The second implementation is a digital communication demo based on W-CDMA, implemented on the FPGA of the SDR14. Four parallel W-CDMA signals of 5 MHz are sent and received by the SDR14. QPSK, 16-QAM, and 64-QAM modulated signals were successfully sent and the mismatch effects were clearly visible in the constellation diagrams. Techniques used are, for example: root-raised cosine pulse shaping, RF modulation, carrier recovery, and timing recovery.
53

Synchronization in all-digital QAM receivers

Pelet, Eric R. 30 April 2009 (has links)
The recent advance in Field Programmable Gate Array (FPGA) technology has been largely embraced by the communication industry, which views this technology as an effective and economical alternative to the design of Application Specific Integrated Circuits (ASICs). The primary reasons for switching to FPGAs are lower development and non-recurring engineering costs, the flexibility to design to a preliminary standard and adapt the design as the standard evolves, as well as the option of performing software updates in the field.<p> A sector with strong interest in FPGAs is the coaxial cable TV/Internet distribution industry. The creation of soft preliminary standards by the standards organization governing the industry has been the main catalyst for the massive adoption of FPGAs by small to medium size companies, which see this technology as an opportunity to compete in this open market.<p> Both the circuit speed and the economy of FPGA technology depend upon using algorithms that map efficiently into its fabric. Often it is prudent to sacrifice performance to improve either clock speed or economy when developing with FPGAs. The purpose of this research is to both revise and devise synchronization algorithms / structures for cable digital receivers that are to be implemented in FPGA. <p> The main communication scheme used by the coaxial cable distribution industry is digital Quadrature Amplitude Modulation (QAM). The problem of synchronizing to the QAM signal in the receiver is not a new topic and several synchronization-related circuits, which were devised with ASICs implementation in mind, can be found in the open literature. Of interest in this thesis is the non-data-aided digital timing synchronizer that was proposed by D'Andrea to recover timing with no knowledge of the transmitted data. Accurate timing estimation was achieved by reshaping the received signal with a prefilter prior to estimating the timing. <p> A problem with D'Andrea's synchronizer is that the prefilter for reshaping the signal is a relatively long Finite Impulse Response (FIR) filter, whose implementation requires a large number of multipliers. This may not have been an issue with ASICs in as much as the number of hardwired multipliers on a chip is not limited as it is in an FPGA chip. One contribution in this research is to propose an alternative to D'Andrea's synchronizer by replacing the long FIR filter with two single-pole Infinite Impulse Response (IIR) filters that are directly placed inside the timing recovery loop. This novel architecture, which drastically reduces the number of multipliers, is well suited for FPGA implementation.<p> Non-data-aided feedforward synchronizers, which use the same prefilter as D'Andrea's synchronizer, have been receiving significant attention in recent years. Detailed performance analysis for these synchronizers can be found in the open literature. These synchronizers have the advantage of using a feedfordward structure rather than a feedback structure, as it is the case in D'Andrea's synchronizer, to estimate the timing. While D'Andrea's synchronizer has an advantage in performance over a non-data-aided feedforward synchronizer, this has not been reported in the literature. In this thesis a second contribution consists of thoroughly analyzing the steady state timing jitter in D'Andrea synchronizer by deriving a closed-form expression for the noise power spectrum and a simple equation to estimate the timing jitter variance. <p> A third contribution is a novel low-complexity and fast acquisition coherent detector for the detection of Quadrature Phase Shift Keying (QPSK) (i.e., 4-QAM) symbols. This detector performs carrier phase synchronization much faster than a conventional coherent detector. The acquisition time is comparable to that of a differential detector. The fast acquisition comes at the expense of phase jitter, and the end result is a 1 dB performance loss over theoretical coherent detection. This detector can be used in place of the differential detector with no economic penalty. Doing so yields a performance advantage of about 2 dB over differential detection.
54

Digital communication can support compassionate leaders and compassionate workplaces

Bradshaw, Jeannine 25 June 2013 (has links)
This thesis explores how digital communication can support compassionate leaders and compassionate workplaces. Through grounded theory methods, exploration and understanding emerged from compassionate leader semi-structured interviews. Emergent themes maintain digital communication can support the evolution of compassionate workplace connectedness and collaboration leading to a compassionate workplace experience. Compassionate leaders stimulating workplace compassion build an atmosphere of trust culminating in increased productivity and a joyful culture where one-on-one to multi-way interaction is supported by digital communication tools.
55

Μεθοδολογίες απεικόνισης αλγορίθμων εμφωλευμένων βρόχων σε VLSI διατάξεις επεξεργαστών

Καραγιάννη, Κωνσταντίνα 24 November 2009 (has links)
- / -
56

A comunicação digital e as transformações nas práticas culturais no contexto organizacional

Temp, Vivian Beatriz January 2008 (has links)
Este trabalho consiste no estudo sobre como a inclusão de ferramentas de comunicação digital nas organizações pode influir na cultura e na comunicação. A ênfase recai na investigação de como a utilização do Correio Eletrônico, da Intranet e das Listas de Discussão podem modificar o processo de comunicação organizacional através da criação de novas práticas culturais que possibilitam a participação dos funcionários no processo comunicativo. A análise resgata o modo como essas ferramentas foram implantadas, a sua apropriação pelos membros organizacionais e as práticas culturais que foram geradas a partir do seu uso. Para isso, realizou-se um estudo de caso na Companhia de Processamento de Dados do Rio Grande do Sul (Procergs). O estudo contempla o relato dos funcionários da organização que utilizam essas ferramentas diariamente nas rotinas de trabalho. Por meio da fala dos participantes, constatou-se que essas ferramentas proporcionam maior envolvimento desses funcionários no processo de comunicação. Entretanto, elas não horizontalizam a relação existente entre os funcionários e a organização, que permanece sendo o espaço de conexão do relacionamento comunicacional. / This master thesis addresses the inclusion of digital communication tools in organizations and how it affects their culture and communication habits. The focus is on how the adoption of Electronic Mail, Intranet and Discussion Lists may change the processes of organizational communication by creating new cultural conventions that enable employees to participate in the communicative process. A case study at Companhia de Processamento de Dados do Rio Grande do Sul (Procergs) were conducted to evaluate how these tools were adopted, how the staff assimilated them and what cultural conventions were created by their use. This case study collected various reports given by staff members who use these tools on the daily work routine. The interviews demonstrated that digital communication tools allow a better involvement of the employees in the communication process. However, the tools by themselves do not equalize the relationship between the organization and its employees, which remains as the connecting space to communicative interaction.
57

A comunicação digital e as transformações nas práticas culturais no contexto organizacional

Temp, Vivian Beatriz January 2008 (has links)
Este trabalho consiste no estudo sobre como a inclusão de ferramentas de comunicação digital nas organizações pode influir na cultura e na comunicação. A ênfase recai na investigação de como a utilização do Correio Eletrônico, da Intranet e das Listas de Discussão podem modificar o processo de comunicação organizacional através da criação de novas práticas culturais que possibilitam a participação dos funcionários no processo comunicativo. A análise resgata o modo como essas ferramentas foram implantadas, a sua apropriação pelos membros organizacionais e as práticas culturais que foram geradas a partir do seu uso. Para isso, realizou-se um estudo de caso na Companhia de Processamento de Dados do Rio Grande do Sul (Procergs). O estudo contempla o relato dos funcionários da organização que utilizam essas ferramentas diariamente nas rotinas de trabalho. Por meio da fala dos participantes, constatou-se que essas ferramentas proporcionam maior envolvimento desses funcionários no processo de comunicação. Entretanto, elas não horizontalizam a relação existente entre os funcionários e a organização, que permanece sendo o espaço de conexão do relacionamento comunicacional. / This master thesis addresses the inclusion of digital communication tools in organizations and how it affects their culture and communication habits. The focus is on how the adoption of Electronic Mail, Intranet and Discussion Lists may change the processes of organizational communication by creating new cultural conventions that enable employees to participate in the communicative process. A case study at Companhia de Processamento de Dados do Rio Grande do Sul (Procergs) were conducted to evaluate how these tools were adopted, how the staff assimilated them and what cultural conventions were created by their use. This case study collected various reports given by staff members who use these tools on the daily work routine. The interviews demonstrated that digital communication tools allow a better involvement of the employees in the communication process. However, the tools by themselves do not equalize the relationship between the organization and its employees, which remains as the connecting space to communicative interaction.
58

Redes sociais virtuais: um estudo da formação, comunicação e ação social / Virtual social networks: a study on the development, communication and social action

Daniel Bonfim da Silva 16 September 2011 (has links)
As redes sociais virtuais são um meio de comunicação que se diferencia da mídia tradicional por uma razão fundamental: a distribuição entre os usuários da capacidade de comunicar. O usuário dessas redes não se limita à posição de espectador, pois ele pode ser também autor, produtor e promotor de textos ou outros materiais. Cai, portanto, o modelo top-down unidirecional, e ganha espaço uma comunicação bidirecional (entre usuários) e difusa, o que representa a transição de uma topologia de árvore para outra, oposta, de rizoma. O objetivo deste trabalho é compreender a comunicação nas redes sociais virtuais, o que será feito analisando-as externa e internamente. Visa-se a formar, dessa maneira, um construto sobre essas redes quanto à sua técnica e seus usuários, sua forma e suas identidades, o que delas irradia e nelas se desenvolve, e, assim, precisar as características fundamentais da comunicação nesses espaços. / Virtual social networks are a means of communication that differs from traditional media due to one fundamental reason: the power to communicate is distributed among their users. In these networks, the user is not merely the spectator, but also the author, the producer, and the promoter of texts or other materials. Therefore, these networks put aside the unidirectional top-down model, giving ground to the emergence of a bidirectional and diffuse communication, which represents a topological transition from tree to rhizome. This research looks for understanding the communication in virtual social networks by analyzing them internally and externally. It seeks building a construct on these networks\' technique and users, their shape and identities, what irradiates from them and what grows in them, thus allowing the understanding of the fundamental communication characteristics in these spaces.
59

A comunicação digital e as transformações nas práticas culturais no contexto organizacional

Temp, Vivian Beatriz January 2008 (has links)
Este trabalho consiste no estudo sobre como a inclusão de ferramentas de comunicação digital nas organizações pode influir na cultura e na comunicação. A ênfase recai na investigação de como a utilização do Correio Eletrônico, da Intranet e das Listas de Discussão podem modificar o processo de comunicação organizacional através da criação de novas práticas culturais que possibilitam a participação dos funcionários no processo comunicativo. A análise resgata o modo como essas ferramentas foram implantadas, a sua apropriação pelos membros organizacionais e as práticas culturais que foram geradas a partir do seu uso. Para isso, realizou-se um estudo de caso na Companhia de Processamento de Dados do Rio Grande do Sul (Procergs). O estudo contempla o relato dos funcionários da organização que utilizam essas ferramentas diariamente nas rotinas de trabalho. Por meio da fala dos participantes, constatou-se que essas ferramentas proporcionam maior envolvimento desses funcionários no processo de comunicação. Entretanto, elas não horizontalizam a relação existente entre os funcionários e a organização, que permanece sendo o espaço de conexão do relacionamento comunicacional. / This master thesis addresses the inclusion of digital communication tools in organizations and how it affects their culture and communication habits. The focus is on how the adoption of Electronic Mail, Intranet and Discussion Lists may change the processes of organizational communication by creating new cultural conventions that enable employees to participate in the communicative process. A case study at Companhia de Processamento de Dados do Rio Grande do Sul (Procergs) were conducted to evaluate how these tools were adopted, how the staff assimilated them and what cultural conventions were created by their use. This case study collected various reports given by staff members who use these tools on the daily work routine. The interviews demonstrated that digital communication tools allow a better involvement of the employees in the communication process. However, the tools by themselves do not equalize the relationship between the organization and its employees, which remains as the connecting space to communicative interaction.
60

Impacto do programa de capacitação no ambiente virtual : estudo de caso de uma rede de professores

Antonio, Liliane de Queiroz 25 August 2005 (has links)
Orientador: Sergio Ferreira do Amaral / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Educação / Made available in DSpace on 2018-08-04T22:12:46Z (GMT). No. of bitstreams: 1 Antonio_LilianedeQueiroz_D.pdf: 317889 bytes, checksum: ed8ce5e1914c4a0e1985bb14a611dd79 (MD5) Previous issue date: 2005 / Resumo: No presente trabalho foi analisado o impacto que um ambiente virtual interativo venha a ter sobre um grupo de professores, por meio de suas manifestações de comunicação e de interatividade bem como a cooperação e a colaboração que um ambiente virtual interativo apresentado como um ferramental pedagógico nas capacitações de professores. O ambiente virtual interativo foi disponibilizado aos assistentes técnicos pedagógicos e aos supervisores de Ensino da Rede Estadual de Educação de São Paulo. Seu eixo central foi o conteúdo de Ensino Religioso que, enquanto necessidade de capacitação para os professores, pode ser discutido e criticado. Foram sugeridas também ações e citações pedagógicas, de forma a realizar a teoria e a prática, a fim de que os alunos de sétimas e oitavas séries do Ensino Fundamental pudessem desenvolver o conceito de Ensino Religioso de maneira pedagógica, sendo construída pelos professores multiplicadores, havendo, assim, uma maior proximidade deles com a sua realidade / Abstract: In current research it was analyzed the impact of a virtual interactive environment over a selected group of professors taking it account not only their behavior of communication and interactivity but also the cooperation and collaboration that the proposed virtual interactive environment would have as a pedagogical tool . The virtual interactive environment was made available to the pedagogical technical assistants and to the teaching supervisors of the State Education Agencies of São Paulo. Its main subject was based on religious teaching that could be used for both professors training and debating. Furthermore, it was suggested pedagogical activities in order to join theory and practice directed to students of 7th and 8th grades. It was expected that this students would develop religious concepts in a pedagogical point of view supported by professors that could assure a closed connection to the reality / Doutorado / Educação, Ciencia e Tecnologia / Doutor em Educação

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