The digital TV transition (also called the digital switchover (DSO) or analog switchoff (ASO), sometimes analog sunset) is the process in which analog television broadcasting is converted to and replaced by digital television. This primarily involves both TV stations and over-the-air viewers; however it also involves content providers like TV networks, and cable TV conversion to digital cable.
Digital TV transition in Brazil began free-to-air HD digital transmissions, after a period of test broadcasts, on Sunday, December 2, 2007 in São Paulo, expanding in January 2008 to Brasília, Rio de Janeiro, and Belo Horizonte. Digital broadcasts will be phased into the other 23 state capitals by the end of 2009, and to the remaining cities by December 31, 2013. Analogue and digital simulcasts will continue until Wednesday, June 29, 2016, when analogue will be discontinued. The main broadcasters (Globo, Record, Band, SBT and RedeTV!) are simulcasting in analogue and digital broadcast, in standard definition and 1080i high definition.
Conversion From Analog to Digital
Digital TV DTV has several advantages over analog TV, the most significant being that digital channels take up less bandwidth (and the bandwidth needs are continuously variable, at a corresponding reduction in image quality depending on the level of compression as well as the resolution of the transmitted image). This means that digital broadcasters can provide more digital channels in the same space, provide high-definition television service, or provide other non-television services such as multimedia or interactivity. DTV also permits special services such as multiplexing (more than one program on the same channel), electronic program guides and additional languages, spoken or subtitled. The sale of non-television services may provide an additional revenue source.
Digital signals react differently to interference than analog signals. For example, common problems with analog television include ghosting of images, noise from weak signals, and many other potential problems which degrade the quality of the image and sound, although the program material may still be watchable. Digitized signals are designed to resist ghosting or noise by using a redundant signal composed of numeric codes. Even if some of the information is missing or wrong, the decoder computer can reconstruct the complete signal. The only way it fails is when the decoder does not receive enough information from the antenna -- if there is too much interference in the signal for the decoder to read enough of the numbers and produce the picture. This can render a digital signal completely or partially unwatchable (picture pixelates or freezes) in situation where an analog signal would still be usable, in urban (ghosting due to multi-path) and rural (weak signal) areas.
Digital signals react differently to interference than analog signals. For example, common problems with analog television include ghosting of images, noise from weak signals, and many other potential problems which degrade the quality of the image and sound, although the program material may still be watchable. Digitized signals are designed to resist ghosting or noise by using a redundant signal composed of numeric codes. Even if some of the information is missing or wrong, the decoder computer can reconstruct the complete signal. The only way it fails is when the decoder does not receive enough information from the antenna -- if there is too much interference in the signal for the decoder to read enough of the numbers and produce the picture. This can render a digital signal completely or partially unwatchable (picture pixelates or freezes) in situation where an analog signal would still be usable, in urban (ghosting due to multi-path) and rural (weak signal) areas.
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