Integrated Services Digital Broadcasting ISDB is a Japanese standard for digital television DTV and digital radio used by the countrys radio and television stations. ISDB replaced the previously used MUSE Hivision analogue HDTV system.Digital television DTV is the sending and receiving of moving images and sound by discrete digital signals, in contrast to the analog signals used by analog TV.The first country to make a wholesale switch to Digital OvertheAir terrestrial broadcasting was the Netherlands, in . This was followed by Finland and Sweden in .In the United States, fullpower television stations are scheduled to change over to digital on June , . By special dispensation, some analog TV signals will cease, as previously scheduled, on February , . This has to do with station resistance to a sudden change in schedule, that will cost broadcasters money and cause logistical nightmares.
In Japan, the switch to digital is scheduled to happen July , . In Canada, it is scheduled to happen August , . China is scheduled to switch in . In the United Kingdom, the digital switchover has different times for each part of the country however, the whole of the UK will be digital by . Brazil switched to digital in December , in major cities and it is estimated years for complete signal expansion over all of the Brazilian territory.While the majority of the viewers of overtheair broadcasting in the USA watch fullpower stations which number about , there are three other categories of TV stations in the USA lowpower stations, Class A stations, and TV translator stations. There is presently no deadline for these stations, about in number, to convert to digital broadcasting.Digital television supports many different picture formats defined by the combination of size, aspect ratio height to width ratio and interlacing. With terrestrial broadcasting in the USA the range of formats can be coarsely divided into two categories HDTV and SDTV. It should be noted that these terms by themselves are not very precise, and many subtle intermediate cases exist.
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