Digital television transition

The digital television transition, also called the digital switchover (DSO), the analogue switch/sign-off (ASO), the digital migration, or the analogue shutdown, is the process in which older analogue television broadcasting technology is converted to and replaced by digital television. Conducted by individual nations on different schedules, this primarily involves the conversion of analogue terrestrial television broadcasting infrastructure to digital terrestrial (DTT), a major benefit being extra frequencies on the radio spectrum and lower broadcasting costs, as well as improved viewing qualities for consumers.

World map of digital television transition progress:
  Transition completed; all analogue signals terminated
  Transition partially completed; some analogue signals terminated
  Transition in progress; broadcasting both analogue and digital signals
  Transition has not been planned or started, or is in early stages
  No digital switchover planned, broadcasting both analogue and digital signals

The transition may also involve analogue cable conversion to digital cable or Internet Protocol television, as well as analog to digital satellite television. Transition of land based broadcasting was begun by some countries around 2000. By contrast, transition of satellite television systems was well underway or completed in many countries by this time. It is an involved process because the existing analogue television receivers owned by viewers cannot receive digital broadcasts; viewers must either purchase new digital TVs, or digital converter boxes which have a digital tuner and change the digital signal to an analog signal or some other form of a digital signal (i.e. HDMI) which can be received on the older TV. Usually during a transition, a simulcast service is operated where a broadcast is made available to viewers in both analogue and digital at the same time. As digital becomes more popular, it is expected that the existing analogue services will be removed. In most places this has already happened, where a broadcaster has offered incentives to viewers to encourage them to switch to digital. Government intervention usually involves providing some funding for broadcasters and, in some cases, monetary relief to viewers, to enable a switchover to happen by a given deadline. In addition, governments can also have a say with the broadcasters as to what digital standard to adopt – either DVB-T, ATSC, ISDB-T, or DTMB. Governments can also require all receiving equipment sold in a country to support the necessary digital 'tuner'.

Before digital television, PAL and NTSC were used for both video processing within TV stations and for broadcasting to viewers. Because of this, the switchover process may also include the adoption of digital equipment using serial digital interface (SDI) on TV stations, replacing analogue PAL or NTSC component or composite video equipment. Digital broadcasting standards are only used to broadcast video to viewers; Digital TV stations usually use SDI irrespective of broadcast standard, although it might be possible for a station still using analogue equipment to convert its signal to digital before it is broadcast, or for a station to use digital equipment but convert the signal to analogue for broadcasting, or they may have a mix of both digital and analogue equipment. Digital TV signals require less transmission power to be broadcast and received satisfactorily.[1]

The switchover process is being accomplished on different schedules in different countries; in some countries it is being implemented in stages as in Australia, Greece, India or Mexico, where each region has a separate date to switch off. In others, the whole country switches on one date, such as the Netherlands.[2] On 3 August 2003, Berlin became the world's first city to switch off terrestrial analogue signals.[3] Luxembourg was the first country to complete its terrestrial switchover, on 1 September 2006.[4]

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