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| Documento principal | 3.87 MB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
Estando prevista a introdução da televisão digital terrestre em Portugal para os próximos anos,
coloca-se o desafio de projectar o seu desenvolvimento, sendo os aspectos do planeamento de
frequências e da cobertura fundamentais para a concepção de um sistema a nível nacional.
Dado que em Portugal se irá utilizar Coded Orthogonal Frequency Division Multiplexing
(COFDM) 8K (6817 portadoras), com alcances máximos de cerca de 67 km por estação
transmissora, neste trabalho, para além de se abordarem os aspectos globais da norma Digital
Video Broadcast (DVB) e das suas variantes terrestre, por cabo, via satélite e móvel,
abordam-se sistemas de difusão terrestres em particular, identificando-se as características do
sistema que terão um forte impacto no planeamento, aspectos de cobertura DVB-T, atribuição
e planeamento de frequências e ferramentas gráficas de planeamento recorrendo a sistemas de
informação geográfica (SIG).
Obtiveram-se resultados do planeamento de uma rede DVB-T em SFN no modo 8K com
COFDM em modulação 64-QAM para a área geográfica da Beira Interior, utilizando uma
frequência que irá ficar disponível após o “switcth-off”.
A tecnologia DVB dá um grande contributo para que no futuro se ocupe menos espectro
radioeléctrico com mais e melhores serviços que os prestados actualmente com tecnologia
analógica, tal contributo só é possível graças ao desenvolvimento de algoritmos complexos
para compressão de vídeo e áudio a transmitir.
No planeamento da rede DVB-T Beira Interior chega-se à conclusão que o número de
emissores e potências utilizadas são menores, comparando com o sistema analógico actual,
conseguindo-se uma cobertura boa de 87% da população, cobertura aceitável de 95% da
população e cobertura portátil interior na cidade da Covilhã.
As the introduction of terrestrial digital TV in Portugal is foreseen for the next years, the endeavour of designing its development needs to be faced, and the aspects of frequency and coverage are essential for the conception and deployment of a system with national availability. As in Portugal the option is to use Coded Orthogonal Frequency Division Multiplexing (COFDM) 8K (6817 carriers), with maximum coverage ranges per Station around 68 km, in this work, besides the general aspects of Digital Video Broadcast (DVB) and its terrestrial, cable, satellite and mobile variants, one specifically addresses terrestrial broadcast systems in particular. The characteristics with the strongest impact in the planning process are identified, as well as DVB-T coverage aspects, frequency assignment and planning, and geographical information systems graphical planning tools issues (GIS). Planning results were obtained for a DVB-T OFDM based network operating at Single Frequency Network (SFN), 8K mode, with 64-QAM modulation. The Beira Interior region was considered, and the frequency band that will be available for this Portuguese region after Switch-off of analog TV was considered. DVB gives a strong contribute to the reduction of spectrum wastage in the television broadcast sector while providing more and better services support in comparison to analog TV. This advantage is only possible owing to the development of complex algorithms for the compression of video and audio content to be transmitted. In the region of Beira Interior, Portugal, the number of transmitting stations and the transmitter powers are clearly lower than the ones for the today analog TV system. The following follows were achieved for the actual coverage of the population: “good” coverage of 87% of the population, acceptable coverage of 95% of the population and portable indoor coverage within the city of Covilhã.
As the introduction of terrestrial digital TV in Portugal is foreseen for the next years, the endeavour of designing its development needs to be faced, and the aspects of frequency and coverage are essential for the conception and deployment of a system with national availability. As in Portugal the option is to use Coded Orthogonal Frequency Division Multiplexing (COFDM) 8K (6817 carriers), with maximum coverage ranges per Station around 68 km, in this work, besides the general aspects of Digital Video Broadcast (DVB) and its terrestrial, cable, satellite and mobile variants, one specifically addresses terrestrial broadcast systems in particular. The characteristics with the strongest impact in the planning process are identified, as well as DVB-T coverage aspects, frequency assignment and planning, and geographical information systems graphical planning tools issues (GIS). Planning results were obtained for a DVB-T OFDM based network operating at Single Frequency Network (SFN), 8K mode, with 64-QAM modulation. The Beira Interior region was considered, and the frequency band that will be available for this Portuguese region after Switch-off of analog TV was considered. DVB gives a strong contribute to the reduction of spectrum wastage in the television broadcast sector while providing more and better services support in comparison to analog TV. This advantage is only possible owing to the development of complex algorithms for the compression of video and audio content to be transmitted. In the region of Beira Interior, Portugal, the number of transmitting stations and the transmitter powers are clearly lower than the ones for the today analog TV system. The following follows were achieved for the actual coverage of the population: “good” coverage of 87% of the population, acceptable coverage of 95% of the population and portable indoor coverage within the city of Covilhã.
Description
Keywords
Televisão digital terrestre - Portugal Televisão digital terrestre - Planeamento de rede - Portugal BUD-T (Digital Video Broadcasting-Territorial) OFDM (Orthogonal Frequency Division Multiplex) Padrão H.264/AVC (Video Coding Standard/Advanced Video Coding)
Citation
Publisher
Universidade da Beira Interior