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; as of 2022, 55 countries are actively running DAB broadcasts.^[3][4]

DAB was the result of a European research project and first publicly rolled out in 1995, with consumer-grade DAB receivers appearing at the start of this millennium. 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.^[5][6][7][8] As of 2023^[update], Norway is the first country to have implemented a national FM radio switch-off,^[9][10] with others to follow in the next years.^[11][12][13] In recent years, DAB has become the most popular radio listening platform in Norway, Switzerland and the UK,^[14] and has become a requirement for all new cars sold in the EU since 2021.^[15]

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+.^[16] Today the majority of DAB broadcasts around the world are using the upgraded DAB+ standard, with only the UK, Romania, Brunei, and the Philippines still using a significant number of legacy DAB broadcasts.

DAB is generally more efficient in its use of spectrum than analogue FM radio,^[17] 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,^[18] 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 more effective coverage over a larger area.^{[citation needed]} DAB+ is a "green" platform and can bring up to 85 percent energy consumption savings^[19] compared to FM broadcasting (but analog tuners are more efficient than digital ones,^[20] and DRM+ has been recommended for small scale transmissions).^[21]

Similar terrestrial digital radio standards are HD Radio, ISDB-Tb, DRM, and the related DMB.^[22]