What is Digital Television? 

TV is currently undergoing a transition from analogue broadcasting to digital broadcasting. This is probably the biggest change in TV since the introduction of colour televisions. Digital broadcasting is essentially the broadcasting of TV or radio programme content as a stream of digital data. The ability to transmit TV content in the form of data in this way means that more information can be transmitted over a digital network than the old analogue networks. As a result a digital broadcasting network can be used to provide more versatile services such as more TV channels, radio channels, digital quality pictures and sound, high definition pictures, enhanced teletext, electronic programme guides and even interactive services.

Digital television is commonly available in Ireland over commercial re-broadcasting services - cable, MMDS or satellite.  In September 2009, ComReg reported (ComReg Quarterly Report) that 62.1% of TV households have digital TV on at least 1 TV set. Other technologies such as Internet Protocol Television (IPTV) are also starting to emerge.

A new digital television platform –Digital Terrestrial Television (DTT) is expected to be made available shortly in Ireland.  RTÉ will provide a free to air DTT service with capacity to replace the existing analogue terrestrial TV service currently provided by RTÉ, TV3 and TG4. The DTT service will provide for the  availability of free to air public service broadcasting in Ireland over a digital network.


In addition, commercial DTT services are expected to be made available by a commercial operator under contract from the Broadcasting Authority of Ireland. (BAI).

The latest information on the RTE’s DTT services is available from RTÉ.  Information on commercial DTT services is available from the BAI.

How is Digital Television received?

Digital television operates by first of all converting the pictures, sound, text and other information making up the TV content into digital data elements. This data is then compressed/squeezed for broadcasting to TV viewers. TV signals are broadcast over the air or via a cable connection to the viewer's premises. At the viewer's premises, the broadcast data is received via an aerial, satellite dish or cable and is decoded – by a digital decoder. The digital decoder converts the data into pictures, sound, text and other information which can be broadcast over the TV.

In its simplest form a decoder can take the form of a set top box which is connected to the TV. Subscribers to Cable, MMDS or Satellite will be familiar with these devices. Some decoders also function as a digital video recorder. In developed Digital Terrestrial Television markets the decoder may be an internal device in the TV (iDTV).

Pay TV operators generally encrypt their content so that it can only be viewed by viewers who pay a subscription for the service. In these cases a decoder with decryption capability is required.