Digital Audio Broadcasting
Digital Audio Broadcasting (DAB) is a digital radio standard for broadcasting digital audio radio services in many countries around the world, defined, supported, marketed and promoted by the WorldDAB organisation. The standard is dominant in Europe and is also used in Australia, and in parts of Africa and Asia.
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As of 2022, 55 countries are running DAB services. The majority of these services are using the upgraded DAB+ standard, with only the UK, New Zealand, Romania, Brunei Darussalam, and the Philippines still using a significant number of original DAB services. Initially it was expected in many countries that existing FM services would switch over to DAB, although the take up of DAB has been much slower than expected;. As of 2022[update], Norway is the first country to have implemented a national FM radio switch-off, with others to follow in the next years.
The DAB standard was initiated as a European research project called Eureka-147 in the 1980s. The Norwegian Broadcasting Corporation (NRK) launched the first DAB channel in the world on 1 June 1995 (NRK Klassisk), and the BBC and Swedish Radio (SR) launched their first broadcasts later that year. Consumer-grade DAB receivers have been available in many countries since the start of this millennium. The original version of DAB used the MP2 audio codec; an upgraded version of the system was later developed and released named DAB+ which uses the HE-AAC v2 (AAC+) audio codec and is more robust and efficient. DAB is not forward compatible with DAB+.
DAB is generally more efficient in its use of spectrum than analogue FM radio, and thus can offer more radio services for the same given bandwidth. The broadcaster can select any desired sound quality, from high-fidelity signals for music to low-fidelity signals for talk radio, in which case the sound quality can be noticeably inferior to analog FM. High-fidelity equates to a high bit rate and higher transmission cost. DAB is more robust with regard to noise and multipath fading for mobile listening, although DAB reception quality degrades rapidly when the signal strength falls below a critical threshold (as is normal for digital broadcasts), whereas FM reception quality degrades slowly with the decreasing signal, providing effective coverage over a larger area.
DAB+ is a "green" platform and brings 85 percent energy consumption savings compared to FM broadcasting.