Digital broadcasting

Digital broadcasting is the practice of using digital data rather than analogue waveforms to carry broadcasts over television channels or assigned radio frequency bands. It is becoming increasingly popular for television usage (especially satellite television) but is having a slower adoption rate for radio.

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Digital links, thanks to the use of data compression, generally have more efficient bandwidth usage than analog links, which allows a content provider more room to provide services, or to provide a higher-quality signal than had been previously available.

The premise behind digital broadcasting

NB: For more information on the premise of digital broadcasting refer to the 2002 edition of the World Radio TV Handbook.

Digital broadcasting has been helped greatly thanks to the presence of computers. In fact, with the invention of the integrated circuit in the 1960s and the microprocessor in the 1970s, digital broadcasting seems to have taken a footing in the global village that is broadcasting. However, most broadcasters are switching to digital broadcasting mostly because of a lack of frequency space. For example:

1. In the UK, the FM band is extremely limited. It is only possible to fit three BBC services comfortably: BBC Radio 1, BBC Radio 2, and BBC Radio 3. In most areas BBC Radio 4 is also on FM, but for other locations Radio 4 uses AM and LW because of the lack of space on FM. In fact, this is why BBC Radio Five Live exclusively uses AM. On the commercial radio front, only Classic FM can comfortably fit in FM: Talksport and Virgin Radio use AM. In addition, local radio stations use a mixture of FM and AM. The same can also be said for British television, which exclusively uses the pan-European UHF television band after VHF television (PAL-A) was discontinued in the 1980s. Only BBC1, BBC2, ITV1, and Channel Four could comfortably fit. In addition, Channel Five could broadcast only in a few limited areas because of the strain of the TV band. There are also a few local television stations, but they are mostly low-power and are not affected, if any.

2. In Canada, the Canadian Broadcasting Corporation/Société Radio-Canada (CBC/Radio-Canada) operates four domestic radio networks: CBC Radio One, CBC Radio Two, La première chaîne de Radio-Canada, and Esapce Musique. Originally, Radio One and la Première Chaîne used AM and Radio Two and Esapce Musique used FM. However, most CBC radio broadcasts use FM now, putting strains on the FM radio band. This has left the AM band almost dry, since most local broadcasters are using FM. However, Canada uses the NTSC television system used in the US, so there aren't any problems with television, yet.

3. In South Asia, the Sri Lanka Broadcasting Corporation formerly Radio Ceylon, operates a pioneering FM radio station in Colombo.

4. In addition, there are inherent problems with AM and FM. FM in particular is prone to multipath interference and the need to constantly retune the radio because of problems with the signal. AM, by contrast, doesn't suffer with multipath but when going under bridges or in tunnels, reception is absent. AM in particular (as well as LW and SW) is also prone to conditions on the Sun. RDS, known in the US as RBRS, has alleviated some of the problems with FM, but hasn't been fully implemented in AM.

Thus, because of these problems, most broadcasters are switching to digital techniques.

Related links

• Digital radio
• Digital television
• ATSC Standards
• ATSC tuner
• Digital tuner
• Digital Audio Broadcasting
• Digital Radio Mondiale
• DVB
• HD Radio
• Satellite radio
• Satellite television