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{{Short description|Hybrid analog plus digital radio broadcast system}}
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'''In-band on-channel''' ('''IBOC''') is a hybrid method of transmitting [[digital radio]] and analog radio [[Broadcasting|broadcast]] [[
IBOC relies on unused areas of the existing spectrum to send its signals. This is particularly useful in North America style FM, where channels are widely spaced at 200 kHz but use only about 50 kHz of that [[Bandwidth (signal processing)|bandwidth]] for the audio signal. In most countries, FM channel spacing may be as close as 100 kHz, and on AM it is only 10 kHz. While these all offer some room for additional digital broadcasts, most attention on IBOC is in the FM band in North American systems; in Europe and many other countries, entirely new bands were allocated for all-digital systems.
Digital radio standards generally allow multiple program channels to be multiplexed into a single digital stream. In North American FM, this normally allows two or three high-fidelity signals combined in one channel, or one high-fidelity signal
Eventually, stations can go from digital/analog-hybrid mode to all-digital, by eliminating the baseband [[Monaural|monophonic]] audio.
==FM methods==
On FM there are
===HD Radio Broadcasting===
The first, and
===FMeXtra===
The other system is [[FMeXtra]] by Digital Radio Express, which instead uses subcarriers within the existing signal.
FMeXtra can
===DRM===
[[Digital Radio Mondiale]] allows for simultaneous transmission of multiple data streams alongside an audio signal. The DRM mode for VHF provides bandwidths from between 35
While it is not
==AM methods==
===HD Radio Broadcasting===
iBiquity also created a [[mediumwave]] HD Radio system for AM, which is the only system approved by the Federal Communications Commission for digital AM broadcasting in the United States.<ref>{{cite web |url=http://www.fcc.gov/mb/audio/digital.html |title=FCC digital radio broadcasting |work=United States [[Federal Communications Commission]], audio division |access-date=2010-06-29 |archive-url=https://web.archive.org/web/20100615162704/http://www.fcc.gov/mb/audio/digital.html |archive-date=2010-06-15 |url-status=dead }}</ref>
===DRM===
Digital Radio Mondiale has had much more success {{Citation needed|date=October 2008}} in creating an AM system, and one that could be much less expensive to implement than any [[Proprietary protocol|proprietary]] HD Radio system, although it requires new frequency.
===CAM-D===
[[CAM-D]] is yet another method, though it is more of an extension of the current system.
Critics of CAM-D point to several drawbacks:
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== IBOC Versus DAB ==
While the United Kingdom and many other countries have chosen the Eureka 147 standard of digital audio broadcasting (DAB) for creating a digital radio service, the United States has selected IBOC technology for its digital AM and FM stations.
There was also concern that AM and FM stations' branding, using their current frequencies, would be lost to new channel numbers, though virtual channels such as on digital television would eliminate this. Also, several competing stations would have to share a transmitter that multiplexes them all into one ensemble with the same coverage area (though many FM stations are already diplexed in large cities such as New York). [https://web.archive.org/web/20110725192711/http://www.esbnyc.com/tourism/tourism_facts_broadcasting.cfm] A further concern to FM station operators was that AM stations could suddenly be in competition with the same high audio quality, although FM would still have the advantage of higher data rates (300
The most significant advantage for IBOC is its relative ease of implementation. Existing analog radios are not rendered obsolete and the consumer and industry may transition to digital at a rational pace. In addition, the technology infrastructure is in place: most major broadcast equipment manufacturers are implementing IBOC technology and 60+ receiver manufacturers are selling IBOC reception devices.
An updated version of the Eureka-147 standard called DAB+ has been implemented. Using the more efficient high quality MPEG-4 CODEC HE-AAC v2, this compression method allows the DAB+ system to carry more channels or have better sound quality at the same bit rate as the original DAB system.
==Challenges==
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Both AM and FM IBOC signals cause interference to adjacent-channel stations, but not within the station's interference-free protected contours designated by the U.S. [[Federal Communications Commission]] (FCC). It has led to derogatory terms such as IBAC (In-band adjacent-channel) and IBUZ (since the interference sounds like a buzz.) The range of a station on an HD Radio receiver is somewhat less than its analog signal. In June 2008, a group of US broadcasters and equipment manufacturers requested that the U.S. FCC increase the permissible FM IBOC power from 1% (currently) to a maximum of 10% of the analog power. On January 29, 2010, the FCC approved the request.<ref>{{cite web |url=http://www.fcc.gov/fcc-bin/audio/DA-10-208A1.pdf |archive-url=https://wayback.archive-it.org/all/20140523212426/http://www.fcc.gov/fcc-bin/audio/DA-10-208A1.pdf |url-status=dead |archive-date=2014-05-23 |author=FCC |title=Digital power increase for FM stations approved. MM Docket No. 99-235, DA 10-208. |date=2010-01-29 |access-date=2010-02-26 }}</ref> In addition, tropospheric ducting and e-skip can reduce the range of the digital signal, as well as the analog.
IBOC digital radios using iBiquity's standard are being marketed under the brand "HD Radio" to highlight the purported quality of reception. As of June 2008, over 60 different receiver models have been made, and stations have received blanket (no longer individual and experimental) authorization from the U.S. FCC to transmit in a multiplexed multichannel mode on FM. Originally, the use of HD Radio transmission on AM was limited to daytime only, and not allowed at night due to potential problems with skywave radio propagation.
==IBOC around the world==
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=== Bangladesh ===
Government broadcaster BETAR began broadcasting HD Radio on their 100.0 MHz frequency on 9 November 2016 from their Agargaon site in Dhaka.
=== Bosnia ===
Trial and tests of HD Radio technology began in Sarajevo in March 2007.
===
HD Radio and DRM trials in Brazil started in the mid 2000s. No regular HD Radio or DRM transmissions are allowed in Brazil as the digital radio standard in that country is not yet defined. One or two year experimental licenses were given to some Broadcasters. A joint study by the government (Ministry of Communications and ANATEL) and the National Metrology Institute (Inmetro) was done<ref>{{cite web |url=http://www.comunicacoes.gov.br/testes-com-medicoes |author=Ministério das Comunicações |title=Relatórios de testes com medições. |date=2012-08-08 |access-date=2015-06-08 |archive-url=https://web.archive.org/web/20150623201944/http://www.comunicacoes.gov.br/testes-com-medicoes |archive-date=2015-06-23 |url-status=dead }}</ref> and the Digital Radio Consultative Council concluded that HD Radio and DRM do not meet the same analog transmission coverage<ref>{{cite web |url=http://www.ebc.com.br/noticias/brasil/2013/10/testes-feitos-com-radio-digital-apresentam-alcance-inferior-ao-analogico-diz |author=Empresa Brasil de Comunicação (Brazilian Public Broadcaster) |title=Testes feitos com rádio digital apresentam alcance inferior ao analógico, diz ministério. |date=2013-10-08 |access-date=2015-06-08}}</ref> with 20db less power. New trials are expected to occur before any decision about the Brazilian Digital Radio standard. Brazil is considering for adoption Digital Radio Mondiale or HD Radio.
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=== Mexico ===
All Mexican radio stations [[Border blaster|within 320 km of the U.S. border]] are allowed to transmit their programs on the AM and FM bands utilizing HD Radio technology.
=== New Zealand ===
HD Radio transmission in Auckland, New Zealand was started on October 19, 2005. The frequency of IBOC HD radio is 106.1 MHz. The transmitter is located at Skytower.
=== Philippines ===
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=== Puerto Rico ===
WPRM FM is the first station in San Juan, Puerto Rico (part of the US) to adopt HD Radio, in April 2005.
=== Switzerland ===
FM testing sponsored by Radio Sunshine and Ruoss AG began in Lucerne in April 2006. HD Radio operations in Switzerland continue and are spotlighted each year during “HD Radio Days”, an annual gathering in Lucerne of European broadcasters and manufacturers for the purpose of discussing the rollout of the technology in Europe.
Radio Sunshine has now switched to DAB+ <ref>{{cite web |url=http://www.sunshine.ch/dynasite.cfm?dsmid=98472 |title=Radio Sunshine :: Mehr Musik - mehr Abwechslung! |website=www.sunshine.ch |url-status=dead |archive-url=https://web.archive.org/web/20110510142126/http://www.sunshine.ch/dynasite.cfm?dsmid=98472 |archive-date=2011-05-10}} </ref>
due to the high penetration of DAB+ and lack of interest in HD Radio.
DAB+ penetration in Switzerland has now reached 99.5% as of 2018.<ref>{{Cite web |url=http://www.worlddab.org/country_information_/switzerland |title=
=== Thailand ===
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=== Ukraine ===
The first FM HD Radio broadcasts in
=== Vietnam ===
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As of June 2008, more than 1,700 HD Radio stations were broadcasting 2,432 HD Radio channels. {{Citation needed|date=December 2018}} HD Radio technology is the only digital technology approved by the FCC for digital AM and FM broadcasting in the US. {{Citation needed|date=December 2018}} Over 60 different HD Radio receivers are on sale in over 12,000 stores nationwide, including Apple, Best Buy, Target, and Wal-Mart. {{Citation needed|date=December 2018}}
As of May 2007, FMeXtra is on several dozen stations.
==See also==
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