Radio Links
Mostrando 13-24 de 25 artigos, teses e dissertações.
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13. A discursivização do local-fronteira no jornalismo: estudo de caso de programas jornalísticos em rádios comunitárias
This work investigates the functioning of Journalism in community radios, taking as objects of analysis the journalistic programs Realidade Urgente e Bom Dia Cidade, of the radio stations Nova Aurora FM, from Santana do Livramento, and Elshaday FM, from Uruguaiana, both towns in the state of Rio Grande do Sul. The main concern of this research is the way the
Publicado em: 2008
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14. Dimensioning ad hoc networks : traffic and interference combined / Dimensionamento em redes ad hoc : trafego e interferencia combinados
Ad hoc networks are networks that operate without centralized control, whose nodes communicate through wireless links in a single or multihop way. A complex issue about ad hoc networks is the capacity estimation. The computation of how many transmissions the network can support ensuring a quality of service for its users is a difficult task due to two centra
Publicado em: 2007
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15. A SEMI-EMPIRIC CONSISTENT MODEL FOR RAIN ATTENUATION PREDICTION IN TERRESTRIAL AND SATELLITE RADIO LINKS / PREVISÃO DA ATENUAÇÃO POR CHUVAS ATRAVÉS DE UMA MODELAGEM SEMI-EMPÍRICA CONSISTENTE PARA ENLACES RÁDIO TERRESTRE E VIA SATÉLITE
Com a crescente utilização de sistemas de acesso sem fio ponto-multiponto em banda larga, operando em freqüências cada vez mais elevadas, cresce também a necessidade do desenvolvimento de novos modelos, mais precisos e consistentes, para a previsão da atenuação por chuvas, principal efeito da propagação em freqüências superiores a 10 GHz. Este tr
Publicado em: 2006
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16. Image and data telemetry for an autonomous water quality monitoring platform / Telemetria de dados e imagens para plataforma autônoma para coleta de dados hidrológicos
The data acquisition of the water chemical and physical variables in lakes and reservoirs is of extreme importance. Monitoring the quality of water supplied and consumed in our cities we are protecting the most valuable of our natural resources, and consequently our own lifes. Monitoring data quality, still in our days, is done in a conventional and hard man
Publicado em: 2006
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17. Utilização do módulo "creatalink" para a transmissão, em tempo real, de sinais de correção para sistemas GPS diferenciais (DGPS) / Use of creatalink module to transmit in real time corrections signals for differential GPS (DGPS) systems
GPS is a radio navigation system base on a satellite network providing 24 hours radio data to determine point coordinates and world wide coverage. The precision is in the decametric range which is not adequate to many applications. DGPS or Differential GPS is a technique used to improve this precision down to metric level adding informa-tion to the receiver.
Publicado em: 2005
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18. MODELAMENTO DE EFEITOS DE MULTIPERCURSO ATMOSFÉRICO EM ENLACES MICROONDAS EM VISIBILIDADE. / MODELING ATMOSPHERIC MULTIPATH FADING IN LINE-OF-SIGHT MICROWAVE LINKS
Os desvanecimentos por multipercurso atmosférico são a principal causa de degradação do desempenho de enlaces rádio digitais de alta capacidade, acentuando os efeitos do ruído térmico e da interferência intersimbólica na taxa de bits errados. A previsão da distribuição cumulativa de probabilidades destes desvanecimentos em função de parâmetros
Publicado em: 2003
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19. MODELLING TO RAIN ATTENUATION EFECTS IN POINT-TO-POINT AND POINT-TO-MULTIPOINT TERRESTRIAL LINKS / MODELAMENTO DE EFEITOS DE ATENUAÇÃO POR CHUVAS EM ENLACES TERRESTRES PONTO-A-PONTO E PONTO-MULTIPONTO
The growing demand for broadband services such as high- speed data, video, audio and multimedia, has lead to the use of point-multipoint radio systems operating in frequencies above of 10 GHz, that are not yet allocated for other services and allow the use of the large bandwidths required by these services. At these frequencies, the main contribution for the
Publicado em: 2003
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20. MEDIDAS DE PROPAGAÇÃO PARA DIMENSIONAMENTO DE ENLACES TERRESTRES RÁDIO-DIGITAIS / PROPAGATION MEASUREMENTS FOR TERRESTRIAL DIGITAL RADIO LINKS
The aim this work was to obtain design parameters for terrestrial digital systems, and to Access their reliability and quality. These design parameters were obtained from measurements made in analogic links operated by the Brazilian telecommunication company Telebrás and Telesc, localised throughout Brazil.The techniques necessary to obtain the data were de
Publicado em: 1996
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21. METODOLOGIAS USUAIS PARA O CÁLCULO DE ENLACES DIFRATADOS: ANÁLISE DE ERRO E CORREÇÕES PROPOSTAS / USUAL METHODOLOGIES FOR THE DIFRACTED LINKS: ERROR ANALYSIS AND PROPOSED CONECTIONS
Na analysis of usual error methodologies for claculating the difraction losses, were made from data obtained from 56 experimental links. This data was analised by a computer program, where different types of methodos and obstacles were simulated. The results of these observation led to the application of the necessary correction in function of the desired ma
Publicado em: 1995
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22. UM MÉTODO PARA ANÁLISE DA DIVERSIDADE EM ESPAÇO EM SISTEMAS RÁDIO DIGITAIS / A METHOD FOR SPACE DIVERSITY ANALYSIS IN DIGITAL RADIO SYSTEMS
A method base don the concept of signature for analysis of the improvement related to vertical antenna separation on digital radio with space diversity was developed. The analysis was performed on selective fading statistics obtained from measurements in LOS links in Brazil. The results reveal the existence of an optimum antenna separation. Also, a predictio
Publicado em: 1988
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23. OPTIMIZATION OF MICROWAVE ROUTES BY THE DUAL DECOMPOSITION / OTIMIZAÇÃO DE ROTAS DE MICROONDAS POR DUALIZAÇÃO
The purpose of this work is to present a method for optimization of microwave routes in radio relay links, using decompositions techniques. The mathematical model is based on microwaves systems design criteria adopted in Brasil by the Empresa Brasileira de Telecomunicações S.A., EMBRATEL, and consists of a nonlinear objective function, several inequalities
Publicado em: 1983
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24. INVESTIGAÇÃO TEÓRICO-EXPERIMENTAL SOBRE O COMPORTAMENTO DO DESVANECIMENTO RÁPIDO NAS LIGAÇÕES DE MICRO-ONDAS EM VISIBILIDADE / THEORETHICAL AND EXPERIMENTAL INVESTIGATION OF FAST FADING IN LINE-OF-SIGHT MICROWAVES LINKS
The purpose of this work is to present a mathematical model to interpret theoreticallly the statistical behavior of deep fades in line-of-sight microware paths. The previous theories are discussed and compared to the known experimental data. A simple model is used to obtain a theoretical dependence of the fades deepth with the path roughness. The results sho
Publicado em: 1977