Editing Digital Audio Broadcasting (section)

==Strengths and weaknesses==
===Benefits of DAB===
====Improved features for users====
DAB devices perform band-scans over the entire frequency range, presenting all stations from a single list for the user to select from.

DAB is capable of providing metadata alongside the audio stream. Metadata allows visual information, text and graphics - such as the station name and logo, presenter, song title and album artwork - to be displayed while a station is playing. Radio stations can provide the metadata to augment the listening experience, particularly on car receivers which have large display panels.<ref>{{cite web |url=https://www.worlddab.org/system/news/documents/000/012/819/original/WorldDAB_look_your_best.pdf?1666945342 |title=Make sure you look your best in the car, WorldDAB urges radio stations |author=WorldDAB |website=WorldDAB.org |date=29 October 2023 |access-date=1 July 2023 |archive-date=22 June 2023 |archive-url=https://web.archive.org/web/20230622005350/https://www.worlddab.org/system/news/documents/000/012/819/original/WorldDAB_look_your_best.pdf?1666945342 |url-status=live }}</ref>

{{anchor|DLS}}DAB can carry "radiotext" (in DAB terminology, ''Dynamic Label Segment'', or DLS) from the station giving real-time information such as song titles, music type and news or traffic updates, of up to 128 characters in length. This is similar to a feature of FM called [[Radio Data System|RDS]], which enables a radiotext of up to 64 characters.

The DAB transmission contains a local [[time of day]] and so a device may use this to automatically correct its internal clock when travelling between time zones and when changing to or from [[Daylight Saving]].

====More stations====
DAB is not more bandwidth efficient than analogue measured in programmes per MHz of a specific transmitter (the so-called [[link spectral efficiency]]), but it is less susceptible to co-channel interference (cross talk), which makes it possible to reduce the [[reuse distance]], i.e. use the same radio frequency channel more densely. The [[system spectral efficiency]] (the average number of radio programmes per MHz and transmitter) is a factor three more efficient than analogue FM for local radio stations. For national and regional radio networks, the efficiency is improved by more than an order of magnitude due to the use of [[single-frequency network|SFN]]s. In that case, adjacent transmitters use the same frequency.

In certain areas – particularly rural areas – the introduction of DAB gives radio listeners a greater choice of radio stations. For instance, in [[Southern Norway]], radio listeners experienced an increase in available stations from 6 to 21 when DAB was introduced in November 2006.

====Reception quality====
The DAB standard integrates features to reduce the negative consequences of [[multipath propagation|multipath]] fading and [[signal noise]], which afflict existing [[analog signal|analogue]] systems.

Also, as DAB transmits digital audio, there is no hiss with a weak signal, which can happen on FM. However, radios in the fringe of a DAB signal can experience a "bubbling mud" sound interrupting the audio or the audio cutting out altogether.

Due to sensitivity to [[Doppler shift]] in combination with [[multipath propagation]], DAB reception range (but not audio quality) is reduced when travelling speeds of more than 120 to 200&nbsp;km/h, depending on carrier frequency.<ref name="tech.ebu.ch">{{cite journal |title=Digital Audio Broadcasting – radio now and for the future |journal=EBU Technical Review |issue=265 |publisher=[[European Broadcasting Union]] |date=Autumn 1995 |pages=2–27 |url=https://tech.ebu.ch/docs/techreview/trev_265-kozamernik.pdf |access-date=14 January 2022 |archive-date=11 August 2017 |archive-url=https://web.archive.org/web/20170811000748/https://tech.ebu.ch/docs/techreview/trev_265-kozamernik.pdf |url-status=live }}</ref>

====Variable bandwidth====
Mono talk radio, news and weather channels and other non-music programs need significantly less bandwidth than a typical music radio station, which allows DAB to carry these programmes at lower bit rates, leaving more bandwidth to be used for other programs.

However, this led to the situation where some stations are being broadcast in mono; see ''{{Section link|#Audio quality}}'' for more details.

====Transmission costs====
DAB transmitters are inevitably more expensive than their FM counterparts. DAB uses higher frequencies than FM and therefore there may be a need to compensate with more transmitters to achieve the same coverage as a single FM transmitter. DAB is commonly transmitted by a different company from the broadcaster who then sells the capacity to a number of radio stations. This shared cost can work out cheaper than operating an individual FM transmitter.

This efficiency originates from the ability a DAB network has in broadcasting more channels per transmitter/network. One network can broadcast 6–10 channels (with MP2 audio codec) or 10–18 channels (with HE AAC codec). Hence, it is thought that the replacement of FM-radios and FM-transmitters with new DAB-radios and DAB-transmitters will not cost any more compared with new FM facilities. It is also argued that the power consumption will be lower for stations transmitted on a single DAB multiplex compared with individual analog transmitters.<ref>{{cite web |last=Garfors |first=Gunnar |title=DAB 20 Times Greener Than FM |url=http://www.garfors.com/2011/01/dab-vs-fm-on-power-consumption.html |access-date=21 June 2012 |url-status=dead |archive-url=https://web.archive.org/web/20161013221809/http://www.garfors.com/2011/01/dab-vs-fm-on-power-consumption.html |archive-date=13 October 2016}}</ref>

Once applied, one operator has claimed that DAB transmission is as low as one-nineteenth of the cost of FM transmission.<ref>{{cite magazine |url=http://www.radioworld.com/tech-and-gear/0003/italys-south-tyrol-begins-fm-switch-off/340879 |title=Italy's South Tyrol Begins FM Switch off |author=Davide Moro |magazine=Radio World |date=12 December 2017 |quote=For us, DAB+ is 19 times more efficient than FM |access-date=18 December 2017 |archive-url=https://web.archive.org/web/20171216072017/http://www.radioworld.com/tech-and-gear/0003/italys-south-tyrol-begins-fm-switch-off/340879 |archive-date=16 December 2017 |url-status=dead }}</ref>

===Disadvantages of DAB===

====Reception quality====
The reception quality during the early stage of deployment of DAB was poor even for people who live well within the coverage area. The reason for this is that DAB uses weak [[error correction coding]], so that when there are a lot of errors with the received data not enough of the errors can be corrected and a "bubbling mud" sound occurs. In some cases a complete loss of signal can happen. This situation has been improved upon in the newer DAB+ version that uses stronger [[error correction coding]] and as additional transmitters are built.

As with other digital systems, when the signal is weak or suffers severe interference, it will not work at all. DAB reception may also be a problem for receivers when the wanted signal is adjacent to a stronger one. This was a particular issue for early and low cost receivers.

====Audio quality====
Up to the mid-2010s, a common complaint by listeners is that broadcasters 'squeeze in' more stations per ensemble than recommended<ref name=":1" /> by:
*Minimizing the bit-rate, to the lowest level of sound-quality that listeners are willing to tolerate, such as 112&nbsp;kbit/s for stereo and even 48&nbsp;kbit/s for mono speech radio (LBC 1152 and the Voice of Russia are examples).
*Having few digital channels broadcasting in stereo.

====Signal delay====
The nature of a [[single-frequency network]] (SFN) is such that the transmitters in a network must broadcast the same signal at the same time. To achieve synchronization, the broadcaster must counter any differences in propagation time incurred by the different methods and distances involved in carrying the signal from the multiplexer to the different transmitters. This is done by applying a delay to the incoming signal at the transmitter based on a timestamp generated at the multiplexer, created taking into account the maximum likely propagation time, with a generous added margin for safety. Delays in the audio encoder and the receiver due to digital processing (e.g. deinterleaving) add to the overall delay perceived by the listener.<ref name="tech.ebu.ch"/> The signal is delayed, usually by around 1 to 4 seconds and can be considerably longer for DAB+. This has disadvantages:
*DAB radios are out of step with live events, so the experience of listening to live commentaries on events being watched is impaired;
*Listeners using a combination of analogue (AM or FM) and DAB radios (e.g. in different rooms of a house) will hear a mixture when both receivers are within earshot.

[[Time signal]]s, on the contrary, are not a problem in a well-defined network with a fixed delay. The DAB multiplexer adds the proper offset to the distributed time information. The time information is also independent from the (possibly varying) audio decoding delay in receivers since the time is not embedded inside the audio frames. This means that built in clocks in receivers can be precisely correct.

====Transmission costs====
DAB can provide savings for networks of several stations. The original development of DAB was driven by national network operators with a number of channels to transmit from multiple sites. However, for individual stations such as small community or local stations which traditionally operate their own FM transmitter on their own building the cost of DAB transmission will be much higher than analog. Operating a DAB transmitter for a single station is not an efficient use of spectrum or power. With that said, this can be solved to some degree by combining multiple local stations in one DAB/DAB+ mux, similar to what is done on DVB-T/DVB-T2 with local TV stations.

====Coverage====
Household receiver penetration rates. {{As of|2021}}:<ref>{{Cite web |url=https://www.worlddab.org/public_document/file/1558/WorldDAB_infographic_H2_2021_FINALr1.pdf?1678185075 |title=Archived copy |access-date=1 July 2023 |archive-date=26 June 2023 |archive-url=https://web.archive.org/web/20230626153617/https://www.worlddab.org/public_document/file/1558/WorldDAB_infographic_H2_2021_FINALr1.pdf?1678185075 |url-status=live }}</ref>
{| class="wikitable collapsible mw-collapsed sortable"
!Country
!Penetration<br />(% of households)
|-
|[[Norway]]
|71
|-
|[[Australia]]
|68.5
|-
|[[United Kingdom]]
|65
|-
|[[Germany]]
|34
|-
|[[Denmark]]
|31
|-
|[[Belgium]]
|21
|-
|[[France]]
|14
|-
|[[Italy]]
|13
|}

Although FM coverage still exceeds DAB coverage in most countries implementing any kind of DAB services, a number of countries moving to digital switchover have undergone significant DAB network rollouts; as of 2022, the following coverages were given by WorldDAB:<ref name="worlddab.org"/>

{| class="wikitable collapsible mw-collapsed sortable"
!Country
!Coverage<br />(% of population)
|-
|[[Kuwait]]
|100
|-
|[[Malta]]
|100
|-
|[[Monaco]]
|100
|-
|[[Denmark]]
|99.9
|-
|[[Norway]]
|99.7
|-
|[[Switzerland]]
|99.5
|-
|[[Germany]]
|98
|-
|[[United Kingdom]]
|97.3
|-
|[[Belgium]]
|97
|-
|[[Czech Republic]]
|95
|-
|[[Netherlands]]
|95
|-
|[[Gibraltar]]
|90
|-
|[[South Korea]]
|90
|-
|Qatar
|90
|-
|Croatia
|90
|-
|[[Italy]]
|86
|-
|[[Slovenia]]
|85
|-
|[[Austria]]
|83
|-
|Serbia
|78
|-
|[[Tunisia]]
|75
|-
|[[Poland]]
|67
|-
|[[Digital radio in Australia|Australia]]
|66
|-
|Estonia
|50
|-
|Slovakia
|46
|-
|[[Sweden]]
|43
|-
|[[France]]
|42
|-
|[[Azerbaijan]]
|33
|-
|Turkey
|30
|-
|Montenegro
|29
|-
|[[Spain]]
|20
|-
|Thailand
|17
|-
|Algeria
|8
|-
|[[Ukraine]]
|7
|-
|[[Greece]]
|{{dunno}}
|-
|Indonesia
|{{dunno}}
|}

====Compatibility====
In 2006 tests began using the much improved [[HE-AAC]] codec for [[DAB+]]. Hardly any of the receivers made before 2008 support the newer codec, however, making them partially obsolete once DAB+ broadcasts begin and completely obsolete once all [[MPEG-1 Audio Layer II|MP2]] encoded stations are gone. Most new receivers are both DAB and DAB+ compatible; however, the issue is exacerbated by some manufacturers disabling the DAB+ features on otherwise compatible radios to save on licensing fees when sold in countries without current DAB+ broadcasts.

====Power requirements====
[[File:Roberts Sports DAB 5 Portable DAB and FM Radio.jpg|thumb|right|Portable DAB/DAB+ and FM receiver, circa 2016. This unit requires two [[AA battery|"AA" size batteries]] ([[headphones]] not shown).]]
As DAB requires digital signal processing techniques to convert from the received digitally encoded signal to the analogue audio content, the complexity of the electronic circuitry required to do this is higher. This translates into needing more power to effect this conversion than compared to an analogue FM to audio conversion, meaning that portable receiving equipment will have a much shorter battery life, and require higher power (and hence more bulk). This means that they use more energy than analogue Band II VHF receivers. However, thanks to increased integration (radio-on-chip), DAB receiver power usage has been reduced dramatically, making portable receivers far more usable.