View source for HD Radio

{{short description|Digital radio broadcast technology}}
{{use dmy dates|date=August 2021}}
[[File:Hdradio-logo.svg|right|200px|HD Radio logo.|thumb]]
{{Digital radio broadcast standards}}

'''HD Radio''' ('''HDR''')<ref>{{cite web |title=HDR/FM Nomad Analyzer |publisher=Octave Communications - Broadcasting and Telecommunication Engineering Services |website=octavecom.ca |url=https://octavecom.ca/hdr.html}}</ref> is a [[trademark]] for [[in-band on-channel]] (IBOC) [[digital radio]] broadcast technology. HD radio generally [[simulcast]]s an existing analog radio station in digital format with less noise and with additional text information. HD Radio is used primarily by [[FM broadcasting|FM]] [[radio station]]s in the United States, U.S. Virgin Islands, Canada, Mexico and the Philippines,{{citation needed|reason=Any articles (clue: from KBP)? Which stations broadcast in it?|date=August 2024}} with a few implementations outside North America.

HD Radio transmits the digital signals in unused portions of the same band as the analog AM and FM signals. As a result, radios are more easily designed to pick up both signals, which is why the HD in HD Radio is sometimes referred to stand for '''Hybrid Digital''', not "High Definition".<ref>{{Cite web |title=Current HD Radio Offerings |url=https://www.mpr.org/listen/hd-radio |access-date=2025-05-14 |website=Minnesota Public Radio |language=en-US}}</ref> Officially, HD is not intended to stand for any term in HD Radio, it is simply part of [[iBiquity]]'s trademark, and does not have any meaning on its own.<ref>{{Cite web |url=http://www.ibiquity.com/about_us/trademarks |title=iBiquity Digital Corporation – Trademarks<!-- Bot generated title --> |access-date=10 December 2024 |archive-date=27 March 2015 |archive-url=https://web.archive.org/web/20150327190846/http://ibiquity.com/about_us/trademarks |url-status=dead }}</ref> HD Radios tune into the station's analog signal first and then look for a digital signal. The European DRM system shares channels similar to HD Radio, but the European DAB system uses different frequencies for its digital transmission.<ref>{{Cite web|url=https://www.pcmag.com/encyclopedia/term/hd-radio|title=Definition of HD Radio|website=PCMAG}}</ref>

The term "on channel" is a misnomer because the system actually sends the digital components on the ordinarily unused channels ''adjacent to'' an existing [[radio station]]'s allocation. This leaves the original analog signal intact, allowing enabled receivers to switch between digital and analog as required. In most FM implementations, from 96 to 128&nbsp;kbit/s of capacity is available. High-fidelity audio requires only 48&nbsp;kbit/s so there is ample capacity for additional channels, which HD Radio refers to as "multicasting".

HD Radio is licensed so that the simulcast of the main channel is royalty-free. The company makes its money on fees on additional multicast channels. Stations can choose the quality of these additional channels; music stations generally add one or two high-fidelity channels, while others use lower bit rates for voice-only news and sports. Previously these services required their own transmitters, often on low-fidelity AM. With HD, a single FM allocation can carry all of these channels, and even its lower-quality settings usually sound better than AM.

While it is typically used in conjunction with an existing channel it has been licensed for all-digital transmission as well. Four [[AM expanded band|AM]] stations use the all-digital format, one under an experimental authorization, the other three under new rules adopted by the [[FCC]] in October 2020. The system sees little use elsewhere due to its reliance on the sparse allocation of FM broadcast channels in North America; in Europe, stations are more tightly spaced.

==History==
This standard was meant to supersede other [[AM Stereo and Digital AM in and near the United States|existing]] stereophonic standards on AM.

[[iBiquity]] developed HD&nbsp;Radio, and the system was selected by the [[U.S. Federal Communications Commission]] (FCC) in 2002 as a digital audio broadcasting method for the United States.<ref name=Dortch-2002-10-11-FCC>{{cite report |last=Dortch |first=Marlene H. |date=2002-10-11 |title=Digital Audio Broadcasting Systems and their Impact on the Terrestrial Radio Broadcast Service |publisher=U.S. [[Federal Communications Commission]] |url=http://fjallfoss.fcc.gov/edocs_public/attachmatch/FCC-02-286A1.pdf |access-date=2008-12-31}}</ref><ref name=mediaweek>{{cite news |last=Tucker |first=Ken |date=2007-03-22 |title=FCC approves HD Radio rules |website=MediaWeek |publisher=Nielsen Business Media |url=http://www.mediaweek.com/mw/news/tvstations/article_display.jsp?vnu_content_id=1003561802 |access-date=2008-12-31 |url-status=dead |archive-url=https://web.archive.org/web/20071103013650/http://www.mediaweek.com/mw/news/tvstations/article_display.jsp?vnu_content_id=1003561802 |archive-date=November 3, 2007 }}</ref> It is officially known as NRSC‑5, with the latest version being NRSC‑5‑E.<ref name=NRSC-5-E>{{cite web |title=NRSC‑5‑E standard |publisher=National Radio Systems Committee |website=nrscstandards.org |url=https://www.nrscstandards.org/standards-and-guidelines/documents/standards/nrsc-5-e/nrsc-5-e.pdf |access-date=2024-05-01}}</ref>

[[iBiquity]] was acquired by [[DTS (sound system)|DTS]] in September&nbsp;2015 bringing the HD&nbsp;Radio technology under the same banner as [[DTS (sound system)|DTS]]'s eponymous theater [[surround sound]] systems.<ref>{{cite web |title=DTS and iBiquity Digital Corp to make the drive better with HD&nbsp;Radio technology |date=2 September 2015 |website=DTS (dts.com) |publisher=[[DTS (sound system)|DTS]] |url=https://dts.com/discover/dts-and-ibiquity-digital-corp-to-make-the-drive-better-with-hd-radio-technology}}</ref> The HD&nbsp;Radio technology and trademarks were subsequently acquired by [[Xperi|Xperi Holding Corporation]] in 2016.

HD&nbsp;Radio is one of several digital radio standards which are generally incompatible with each other:
* [[FMeXtra]] was a competing U.S. standard, but has been stagnant since the 2010s.
* [[CAM-D|Compatible AM Digital]] (CAM‑D) for [[AM broadcasting|AM stations]].
* [[Digital Audio Broadcasting]] (DAB), [[also known as|a.k.a.]] Eureka&nbsp;147, is the most common standard in Europe.
* [[Digital Radio Mondiale]] ([[Digital Radio Mondiale|DRM‑30]] and [[DRM+]] configurations) was intended mostly for [[shortwave]] radio.

By May&nbsp;2018, [[iBiquity|iBiquity Digital Co.]] claimed its HD&nbsp;Radio technology was used by more than 3,500&nbsp;individual services, mostly in the United States.<ref>{{cite web |title=HD Radio broadcasters |website=HD&nbsp;Radio (hdradio.com) |publisher=[[iBiquity|iBiquity Digital Corporation]] |url=https://hdradio.com/broadcasters}}</ref> This compares with more than 2,200&nbsp;services operating with the [[Digital Audio Broadcasting|DAB system]].

A 400&nbsp;[[kHz]] wide channel is required for HD [[FM broadcast band|FM]] analog-digital hybrid transmission, making its adoption problematic outside of North America. In the United States, [[FM broadcast band|FM channels]] are spaced 200&nbsp;[[kHz]] apart as opposed to 100&nbsp;[[kHz]] elsewhere. Furthermore, long-standing [[FCC]] licensing practice, dating from when receivers had poor adjacent-channel selectivity, assigns stations in geographically overlapping or adjacent [[service contour|coverage areas]] to channels separated by (at least) 400&nbsp;[[kHz]]. Thus most stations can transmit carefully designed digital signals on their adjacent channels without interfering with other local stations, and usually without [[co-channel interference]] with distant stations on those channels.<ref>{{cite report |title=Planning Standards for Terrestrial FM Sound Broadcasting at VHF |date=December 1998 |id=[[ITU]]‑R BS.412 |series=Broadcasting service (sound) (BS Series) |website=itu.int |publisher=[[International Telecommunication Union]] (ITU) |url=https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.412-9-199812-I!!PDF-E.pdf}}</ref> Outside the U.S., the heavier spectral loading of the FM broadcast band makes IBoC systems like HD Radio less practical.

The FCC has not indicated any intent to end analog radio broadcasting as it did with [[analog television]],<ref name=Dortch-2002-10-11-FCC/> since it would not result in the recovery of any [[radio spectrum]] rights which could be sold. Thus, there is no deadline by which consumers must buy an HD receiver.

==Technique==
Digital information is [[Transmission (telecommunications)|transmitted]] using [[OFDM]] with an [[audio compression format]] called HDC ([[High-Definition Coding]]). HDC is a proprietary [[codec]] based upon, but incompatible with, the [[MPEG-4]] standard [[HE-AAC]].<ref>{{cite web |title=Receiving NRSC‑5 |website=theori.io |date=9 June 2017 |url=http://theori.io/research/nrsc-5-c |access-date=14 April 2018 |url-status=live |archive-url=https://web.archive.org/web/20170820185827/http://theori.io/research/nrsc-5-c |archive-date=20 August 2017}}</ref> It uses a [[modified discrete cosine transform]] (MDCT) [[audio data compression]] algorithm.<ref>{{cite book |last1=Jones |first1=Graham A. |last2=Layer |first2=David H. |last3=Osenkowsky |first3=Thomas G. |title=NAB Engineering Handbook |date=2013 |publisher=[[National Association of Broadcasters]] via [[Taylor & Francis]] |isbn=978-1-136-03410-7 |pages=558–559 |url=https://books.google.com/books?id=K9N1TVhf82YC&pg=PA558}}</ref>

HD equipped stations pay a one-time licensing fee for converting their primary audio channel to [[iBiquity]]'s HD Radio technology, and 3% of incremental net revenues for any additional digital subchannels.<ref>{{cite web |title=iBiquity licensing fact sheet |year=2009 |website=ibiquity.com |publisher=[[iBiquity|iBiquity Digital Corporation]] |url=http://www.ibiquity.com/i/Licensing_%20Fact_%20Sheet_2009.pdf |archive-url=https://web.archive.org/web/20110713000748/http://www.ibiquity.com/i/Licensing_%20Fact_%20Sheet_2009.pdf |archive-date=2011-07-13}}</ref> The cost of converting a radio station can run between $100,000 and $200,000.<ref>{{cite web |title=Terrestrial Digital Radio |series=Digital America 2006 |publisher=[[Consumer Electronics Association]] |url=http://www.ce.org/Press/CEA_Pubs/2068.asp |access-date=2008-12-31 |url-status=dead |archive-url=https://web.archive.org/web/20090108040523/http://www.ce.org/Press/CEA_Pubs/2068.asp |archive-date=2009-01-08 }}</ref> Receiver manufacturers who include HD Radio pay a royalty,<ref>{{cite web |title=Becoming an HD&nbsp;Radio IP licensee |website=ibiquity.com |publisher=iBiquity Digital Corporation |url=http://www.ibiquity.com/manufacturers/receiver_manufacturers/license_agreement |access-date=2025-06-07 |url-status=live |archive-url=https://web.archive.org/web/20081231021515/http://www.ibiquity.com/manufacturers/receiver_manufacturers/license_agreement |archive-date=2008-12-31 }}</ref> 
which is the main reason it failed to be fully-adopted as a standard feature.

If the HD receiver loses the primary digital signal (HD‑1), it reverts to the analog signal, thereby providing seamless operation between the newer and older transmission methods. The extra HD‑2 and HD‑3 streams do not have an analog simulcast; consequently, their sound will drop-out or "skip" when digital reception degrades (similar to digital television drop-outs). Alternatively the HD signal can revert to a more robust 20&nbsp;[[kilobit per second|kbit/s]] stream, although the sound quality is then reduced to conventional AM-level. [[Datacasting]] is also possible, with [[metadata]] providing song titles or artist information.

iBiquity Digital claims that the system approaches [[Compact Disc Digital Audio#Audio format|CD quality audio]] and offers reduction of both interference and static.<ref>{{cite web |title=How does HD Digital Radio Sound? |website=HD Digital Radio (hdradio.com) |url=http://www.hdradio.com/how_does_hd_digital_radio_sound.php |access-date=2008-12-31 |url-status=dead |archive-url=https://web.archive.org/web/20090121104611/http://hdradio.com/how_does_hd_digital_radio_sound.php |archive-date=2009-01-21 }}</ref> However, the data rates in HD Radio are substantially lower than from a CD, and the digital signals sometimes interfere with adjacent analog [[AM expanded band|AM band]] stations. (see §&nbsp;[[#AM|AM, below]]).

===AM===
[[File:KNX HDlock.jpg|thumb|right|200px|An example of information displayed by an AM HD station locking.]]

The AM hybrid mode ("MA1") uses 30&nbsp;[[kHz]] of bandwidth (±15&nbsp;[[kHz]]), and overlaps [[adjacent channel]]s on both sides of the station's assigned channel.<ref name=NRSC-5-D>{{cite web |title=NRSC‑5‑D standard |publisher=National Radio Systems Committee |website=nrscstandards.org |url=https://www.nrscstandards.org/standards-and-guidelines/documents/standards/nrsc-5-d/nrsc-5-d.pdf |access-date=2021-04-14}}</ref> Some nighttime listeners have expressed concern this design harms reception of adjacent channels<ref>{{cite web |last=Zuk |first=Karl  |date=2007-11-20 |orig-year=Sep 2007 |title=Night of the bees |website=Write or Karl me! (karlzuk.blogspot.com) |url=https://karlzuk.blogspot.com/2007/09/night-of-bees.html |access-date=2008-12-31 |url-status=live |archive-url=https://web.archive.org/web/20110708045014/http://karlzuk.blogspot.com/2007/09/night-of-bees.html |archive-date=2011-07-08 }}</ref><ref>MP3 sample of the interference: {{cite AV media |url=http://www.wysl1040.com/media_files/wysl/IBOC_OBSERVATIONS.mp3 |title=IBOC observations |website=[[WYSL]] 1040&nbsp;[[AM expanded band|AM]] (wysl1040.com) |medium=mp3 soundclip |archive-url=https://web.archive.org/web/20090325090032/http://www.wysl1040.com/media_files/wysl/IBOC_OBSERVATIONS.mp3 |archive-date=2009-03-25}}</ref> with one formal complaint filed regarding the matter: [[WYSL]] owner Bob Savage against [[WBZ (AM)|WBZ]] in Boston.{{citation needed|date=March 2025}}

The capacity of a 30&nbsp;[[kHz]] channel on the AM band is limited. By using [[spectral band replication]] the HDC+SBR codec is able to simulate the recreation of sounds up to 15,000&nbsp;Hz, thus achieving moderate quality on the [[Bandwidth (signal processing)|bandwidth]]-tight [[AM expanded band|AM band]].<ref>{{cite web |title=SBR explained |url=http://www.codingtechnologies.com/products/sbr.htm |series=Dolby |publisher=Coding Technologies |access-date=2008-12-31 |url-status=bot: unknown |archive-url=https://web.archive.org/web/20081216004340/http://www.codingtechnologies.com/products/sbr.htm |archive-date=December 16, 2008}}</ref> The HD Radio [[AM expanded band|AM]] hybrid mode offers two options which can carry approximately 40~60&nbsp;[[kilobit per second|kbit/s]] of data, with most [[AM broadcasting|AM]] digital stations defaulting to the more-robust 40&nbsp;[[kilobit per second|kbit/s]] mode, which features redundancy (same data is broadcast twice).

The digital radio signal received on a conventional [[AM expanded band|AM receiver]] tuned to an adjacent channel sounds like [[white noise]] – the sound of a {{cite web |title=hiss |url=https://commons.wikimedia.org/w/index.php?title=File%3AWhite-noise-sound-20sec-mono-44100Hz.ogg |postscript=none}}, or a large waterfall, or a strong, steady wind through a dense [[forest canopy]], or similar.

====All-digital AM====
All-digital AM ("MA3") allows for two modes: "Enhanced" and "core-only".<ref>{{cite web |title=Commission unanimously approves all-digital AM radio broadcasting |date=October 30, 2020 |website=wiley.law |url=https://www.wiley.law/alert-Commission-Unanimously-Approves-All-Digital-AM-Radio-Broadcasting |access-date=2021-05-29}}</ref>
* In enhanced mode, the primary, secondary and tertiary carriers are transmitted, allowing for a maximum throughput of 40.2&nbsp;[[kilobit per second|kbit/s]] while using 20&nbsp;[[kHz]] of bandwidth out to the station's 0.5&nbsp;[[signal strength in telecommunications|mV/m]] [[service contour|contour]]. Inside this contour, stereo audio along with graphics (station logo and "artist experience" album artwork) and text information (the station's call sign, title, album, and artist) can be decoded by the receiver.
: Beyond the station's 0.5&nbsp;[[signal strength in telecommunications|mV/m]] [[service contour|contour]], typically only the primary carriers can be received, which restricts the maximum throughput to 20.2&nbsp;[[kilobit per second|kbit/s]] while only requiring 10&nbsp;[[kHz]] of bandwidth.
* In core-only mode, the station only transmits the primary carriers.

When the receiver can only decode the primary carriers in either mode, the audio will be mono and only text information can be displayed. The narrower bandwidth needed in either all-digital mode compared to hybrid mode reduces possible interference to and from stations broadcasting on adjacent channels.<ref>{{cite report |publisher=Hubbard Radio, LLC |date=March 9, 2020 |title=In the matter of all-digital AM broadcasting revitalization of the AM radio service – comments of Hubbard Radio, LLC |url=https://ecfsapi.fcc.gov/file/10309799215597/Hubbard%20Radio%20Digital%20AM%20NPRM%20Comments.pdf |via=[[Federal Communications Commission]] |docket=MB Docket No.&nbsp;19-311, MB Docket No.&nbsp;13-249 |access-date=2021-04-15}}</ref> However, all-digital AM lacks the analog signal for "fallback" when the signal is too weak for the receiver to decode the primary digital carrier.

Five AM stations have operated as all-digital / digital-only broadcasters, either on an experimental basis or under new rules adopted by the FCC on 27&nbsp;October 2020 that allow any AM station to voluntarily choose to convert to all-digital operation.<ref>{{cite press release |title=FCC authorizes all-digital AM radio |date=27 October 2020 |website=fcc.gov |publisher=[[Federal Communications Commission]] |url=https://docs.fcc.gov/public/attachments/DOC-367780A1.pdf |access-date=2020-10-27}}</ref>
* [[WWFD]] (WSHE since June&nbsp;2024) was granted [[special temporary authority]] from the [[FCC]] in July&nbsp;2018 to broadcast all-digital.<ref>{{cite news |title=WWFD 820&nbsp;AM becomes first all-digital AM station |date=16 July 2018 |website=Radio-Online |url=https://news.radio-online.com/cgi-bin/rol.exe/headline_id=n35675}}</ref>  It continues broadcast in digital-only mode under regular authorization.
* [[WMGG]] broadcast in all-digital mode from January&nbsp;2021 until a new owner returned it to analog-only mode following a station sale in November&nbsp;2021.
* [[WFAS (AM)|WFAS]] broadcast in digital-only mode from May&nbsp;2021 until its license was deleted in October&nbsp;2024.
* [[WSRO]] broadcast in digital only-mode from December&nbsp;2021 until the station went silent in March&nbsp;2023. After a brief return to the air in 2024, its license was cancelled in March&nbsp;2025.
* [[WYDE (AM)|WYDE]] broadcast in all-digital mode from September&nbsp;2023 until June&nbsp;2025 when it returned to broadcasting in hybrid mode.<ref>{{cite web |title=Crawford Will Flip an Alabama AM to All-Digital |date=22 August 2023 |publisher=[[Radio World]] |url=https://www.radioworld.com/tech-and-gear/digital-radio/crawford-will-flip-an-alabama-am-to-all-digital |access-date=2023-08-22}}</ref><ref>[https://radioinsight.com/headlines/302262/fcc-report-6-16-alabama-am-ends-digital-only-operation/ "FCC Report 6/16: Alabama AM Ends Digital-Only Operation"] by Lance Venta, June 15, 2025, radioinsight.com</ref>

The FCC requires stations that wish to multiplex their digital AM signals to request and receive permission to do so.<ref name=october2020/> [[WWFD]] experimented with using a [[digital subchannel]], operating a second channel (HD2) at a low data rate while reducing the data rate of the primary channel (HD1).<ref>{{cite web |last=Fybush |first=Scott |date=6 December 2019 |title=HD‑2 arrives on AM radio |series=NERW extra |website=fybush.com |url=https://www.fybush.com/nerw-extra-hd2-arrives-on-am-radio/ |access-date=2021-04-15}}</ref> In October&nbsp;2020, the [[FCC]] concluded from [[WWFD]]'s experiments:
: "The [experimental] record does not establish that an audio stream on an AM HD-2 subchannel is currently technically feasible".<ref name=october2020>{{cite report |title=All-digital AM broadcasting – revitalization of the AM radio service |series=FCC fact sheet |date=6 October 2020 |id=FCC-CIRC2010-05 / doc&nbsp;367361A1 |publisher=U.S. [[Federal Communications Commission]] |url=https://docs.fcc.gov/public/attachments/DOC-367361A1.pdf}}</ref> In early 2020 the FCC rejected a multiplex request from [[WTLC (AM)|WTLC]].<ref>{{cite news |title=FCC to vote on authorizing all-digital AM |series=FCC Report |date=2020-10-11 |website=radioinsight.com |url=https://radioinsight.com/headlines/199376/fcc-report-10-11-fcc-to-vote-on-authorizing-all-digital-am/}}</ref>

===FM===
[[File:HD-Sideband-DX.ogg|thumb|right|200px|HD Radio DX during a [[Tropospheric ducting|tropo]] opening]]
[[File:FMi 201 FM and HD Radio Transmitter.JPG|thumb|right|200px|HD Radio transmitter]]
[[File:FM spectrum no IBOC.png|thumb|right|200px|Spectrum of FM broadcast station without HD Radio]]
[[File:FM spectrum IBOC.png|thumb|right|200px|Spectrum of FM broadcast station with HD Radio]]
[[File:Pittsburgh-HD-Radio-Emergency-Alert-System-Test.ogv|thumb|right|200px| HD Radio [[Emergency Alert System]] test using [[KDKA-FM]] HD‑1]]

The [[FM broadcast band|FM]] hybrid digital / analog mode offers four options which can carry approximately 100, 112, 125, or 150&nbsp;[[kilobit per second|kbit/s]] of data carrying ([[lossy]]) compressed digital audio depending upon the station manager's power budget and desired range of signal. HD FM also provides several pure digital modes with up to 300&nbsp;[[kilobit per second|kbit/s]] rate, and enabling extra features like surround sound. Like [[AM expanded band|AM]], purely-digital [[FM broadcast band|FM]] provides a "fallback" condition where it reverts to a more robust 25&nbsp;[[kilobit per second|kbit/s]] signal.

FM stations can divide their datastream into sub-channels (e.g., 88.1 HD‑1, HD‑2, HD‑3) of varying audio quality. The multiple services are similar to the [[digital subchannel]]s found in [[ATSC]]-compliant [[digital television]] using [[multiplexed]] broadcasting. For example, some [[top 40]] stations have added [[hot AC]] and [[classic rock]] to their [[digital subchannel]]s, to provide more variety to listeners.<ref>{{cite web |url=http://www.ibiquity.com/hd_radio/hdradio_find_a_station?state=MD&sortBy=undefined&thisBeColorOver=ff920f&thisBeColorOut=11839d#stationlist |title=Stations in Maryland broadcasting on HD Signals |work=iBiquity Digital Corporation |archive-url=https://web.archive.org/web/20110713001240/http://www.ibiquity.com/hd_radio/hdradio_find_a_station?state=MD&sortBy=undefined&thisBeColorOver=ff920f&thisBeColorOut=11839d |archive-date=2011-07-13 |access-date=2016-07-03}}</ref> Stations may eventually go all-digital, thus allowing as many as three full-power channels and four low-power channels (seven total). Alternatively, they could broadcast one single channel at 300&nbsp;[[kilobit per second|kbit/s]].

FCC rules require that one channel be a simulcast of the analog signal so that when the primary digital stream cannot be decoded, a receiver can fall back to the analog signal. This requires [[synchronization]] of the two, with a significant delay added to the analog service.  In some cases, particularly during [[tropospheric ducting]] events, an HD receiver will lock on to the digital stream of a distant station even though there is a much stronger local analog-only station on the [[co-channel|same frequency]]. With no automatic identification of the station on the analog signal, there is no way for the receiver to recognize that there is no correlation between the two.{{efn|
Station identification is sent by voice, or as [[Radio Data System|RBDS]] data, but not all stations transmit RBDS.
}} The listener can possibly turn HD reception off (to listen to the local station, or avoid random flipping between the two stations), or [[TV and FM DX|listen to the distant stations]] and try to get a [[station ID]].

Although the signals may be synchronized at the transmitter and reach the receiving equipment simultaneously, what the listener hears through an HD unit and an analog radio played together can be distinctly unsynchronized. This is because all analog receivers process analog signals faster than digital radios can process digital signals. The digital processing of analog signals in an HD Radio also delays them. The resulting unmistakable "reverb" or echo effect from playing digital and analog radios in the same room or house, tuned to the same station, can be annoying. It is more noticeable with simple voice transmission than with complex musical program content.{{efn|
Note that the "reverb" effect is limited to analog vs. digital receivers, or in rare cases, digital receivers with remarkably different circuitry. Multiple receivers that are all HD (of the same make and model, at least), or multiple receivers that are all analog, in the same room or house, will not produce a noticeable echo.
}}

Stations can transmit HD through their existing antennas using a [[diplexer]], as on [[AM expanded band|AM]], or are permitted by the FCC to use a separate antenna at the same general location, or at a site licensed as an analog [[Backup site|auxiliary]], provided it is within a certain distance and height referenced to the main analog signal. The limitation assures that the two transmissions have nearly the same [[broadcast range]], and that they maintain the proper [[D/U ratio|ratio]] of [[signal strength]] to each other so as not to cause [[destructive interference]] at any given location where they may be received.

====Artist Experience====
<!-- Deleted image removed: [[File:San Diego 96.5 FM KYXY HD2 radio.jpg|thumb|right|200px| Automotive entertainment system displaying song metadata, including "Artist Experience" from San Diego's [[KYXY]] 96.5&nbsp;[[FM broadcast band|FM]] HD‑2.]] -->
HD Radio supports a service called "Artist Experience"<ref>{{cite web |author=Juan@HDRadio [user name] |date=24 July 2013 |title=Artist Experience |website=HD Digital Radio (hdradio.com) |url=http://hdradio.com/broadcasters/engineering-support/artist-experience/ |access-date=14 April 2018 |url-status=live|archive-url=https://web.archive.org/web/20160725040142/http://hdradio.com/broadcasters/engineering-support/artist-experience |archive-date=25 July 2016}}</ref> in which the transmission of album art, logos, and other graphics can be displayed on the receiver. Album art and logos are displayed at the station's discretion, and require extra equipment. An HD Radio manufacturer should pass the [[iBiquity]] certification, which includes displaying the artwork properly.

====EAS alerts====
Since 2016, newer HD Radios support [[Bluetooth]] and [[Emergency Alert System]] (EAS) alerts<ref>{{cite web |author=Juan@HDRadio [user name] |date=28 October 2016 |title=Sparc HD Radio receiver w/Bluetooth and emergency alerts |series=Get a radio / home radio |website=HD Digital Radio (hdradio.com) |url=https://hdradio.com/get-a-radio/home-radio/sparc-hd-radio-receiver-w/bluetooth-and-emergency-alerts |access-date=14 April 2018 |url-status=dead |archive-url=https://web.archive.org/web/20180414172420/https://hdradio.com/get-a-radio/home-radio/sparc-hd-radio-receiver-w/bluetooth-and-emergency-alerts |archive-date=14 April 2018}}</ref> in which the transmission of traffic, weather alerts, [[Amber alert|Amber]] and security alerts can be displayed on the radio. As with "Artist Experience", emergency alerts are displayed at the station's discretion, and require extra equipment.
[[File:HD Radio Romania.jpg|alt=HD Radio bandwidth|thumb|201x201px|Spectrum of a HD Radio station as shown by a RTL-SDR USB device. The usual bandwidth of a regular FM station is visible as the marker width in the top image.]]

====Bandwidth and power====
[[FM stereo]] stations typically require up to 280&nbsp;kilohertz of [[radio spectrum|spectrum]]. The bandwidth of an FM signal is found by doubling the sum of the peak deviation (usually 75&nbsp;[[kHz]]) and the highest baseband modulating frequency (around 60&nbsp;[[kHz]] when [[RBDS]] is used). Only 15&nbsp;[[kHz]] of the baseband bandwidth is used by analog [[monaural]] audio (baseband), with the remainder used for [[FM stereo|stereo]], [[RBDS]], [[pager|paging]], [[radio reading service]], [[Subsidiary Communications Multiplex Operation|rental to other customers]], or as a [[transmitter/studio link]] for in-house [[telemetry]].

In (regular) hybrid mode a station has ±130&nbsp;[[kHz]] of analog bandwidth. The primary main digital sidebands extend ±70&nbsp;[[kHz]] on either side of the analog signal, thus taking a full 400&nbsp;[[kHz]] of spectrum. In extended hybrid mode, the analog signal is restricted to ±100&nbsp;[[kHz]]. Extended primary sidebands are added to the main primary sidebands using the extra ±30&nbsp;[[kHz]] of spectrum created by restricting the analog signal.<ref>{{cite web |url=https://www.nrscstandards.org/standards-and-guidelines/documents/standards/nrsc-5-d/reference-docs/1011s.pdf |title=HD Radio Air Interface Design Description Layer 1 FM |author=<!--Not stated--> |date=August 23, 2011 |website=nrscstandards.org |publisher=iBiquity Digital Corporation |pages=14–16 |access-date=2022-02-15}}</ref> Extended hybrid provides up to approximately 50&nbsp;kbit/s additional capacity.<ref>{{cite web |url=https://www.nrscstandards.org/standards-and-guidelines/documents/standards/nrsc-5-d/nrsc-5-d.pdf |title=NRSC-5-D In-band/on-channel Digital Radio Broadcasting Standard |author=<!--Not stated--> |date=April 2017 |website=nrscstandards.org |publisher=Consumer Technology Association & National Association of Broadcasters |pages=10 |access-date=2022-02-15}}</ref> Any existing [[subcarrier]] services (usually at 92&nbsp;[[kHz]] and 67&nbsp;[[kHz]]) that must be shut down to use extended hybrid can be restored through use of [[digital subchannel]]s. However, this requires the replacement of ''all'' related equipment both for the broadcasters and all of the receivers that use the services shifted to HD subchannels.

The ratio of power of the analog signal to the digital signal was initially standardized at 100:1 (−20&nbsp;dBc), i.e., the digital signal power is 1% of the analog carrier power. This low power, plus the uniform, noise-like nature of the digital modulation, is what reduces its potential for co-channel interference with distant analog stations. Unlike with subcarriers, where the total [[baseband]] [[modulation]] is reduced, there is no reduction to the analog [[carrier wave|carrier]] [[effective radiated power|power]]. The [[National Association of Broadcasters]] (NAB) requested a 10&nbsp;dB (10×) increase<ref>{{cite news |title=NAB will ask FCC to up FM IBOC power |date=2008-02-01 |website=Radio World (radioworld.com) |url=http://www.radioworld.com/pages/s.0100/t.11018.html |access-date=2008-12-31 |publisher=NewBay Media |url-status=dead |archive-url=https://web.archive.org/web/20080804123749/http://www.radioworld.com/pages/s.0100/t.11018.html |archive-date=2008-08-04 }}</ref> in the digital signal from the FCC. This equates to an increase to 10% of the analog carrier power, but no decrease in the analog signal. This was shown to reduce analog coverage because of interference, but results in a dramatic improvement in digital coverage. Other levels were also tested, including a 6&nbsp;dB or fourfold increase to 4% (−14&nbsp;dBc or 25:1). [[National Public Radio]] was opposed to any increase because it is likely to increase interference to their member stations, particularly to their [[broadcast translator]]s, which are secondary and therefore left unprotected from such interference. Other broadcasters are also opposed (or indifferent), since increasing power would require expensive changes in equipment for many, and the already-expensive system has so far given them no benefit.

There are still some concerns that HD FM will increase interference between different stations, even though HD Radio at the 10% power level fits within the FCC spectral mask.<ref>{{cite web  |title=iBiquity spurious noise and emissions mask {{nowrap|TX SSS 1026s rev E}} and FCC Part&nbsp;73.317 FM emission broadcast limits |id=Figure&nbsp;1 1014 |series=Guest commentaries |website=Radio World (radioworld.com) |publisher=New Bay Media, LLC |url=http://www.radioworld.com/uploadedImages/Radio_World/Views/Guest_Commentaries/figure1_1014.jpg |access-date=2009-11-07 |url-status=dead |archive-url=https://web.archive.org/web/20170628000612/http://www.radioworld.com/uploadedImages/Radio_World/Views/Guest_Commentaries/figure1_1014.jpg |archive-date=2017-06-28 }}</ref>  North American [[FM broadcast band|FM channels]] are spaced 200&nbsp;[[kHz]] apart. An HD broadcast station will not generally cause interference to any analog station within its 1&nbsp;[[signal strength in telecommunications|mV/m]] [[service contour]] – the limit above which the FCC protects most stations. However, the IBOC signal resides within the analog signal of the immediately adjacent station(s). With the proposed power increase of 10&nbsp;dB, the potential exists to cause the degradation of the second-adjacent analog signals within its 1&nbsp;[[signal strength in telecommunications|mV/m]] [[service contour|contour]].<ref>{{cite conference |last=Veriner |first=Doug |year=2006 |title=IBOC Coverage and InterferenceIBOC Coverage and Interference |url=http://www.v-soft.com/web/IBOC%20Coverage%20and%20Interference%20Issues2.pdf |access-date=2008-12-31 |url-status=dead |archive-url=https://web.archive.org/web/20090325090032/http://www.v-soft.com/web/IBOC%20Coverage%20and%20Interference%20Issues2.pdf |archive-date=2009-03-25 }}</ref><ref>{{cite web |title=HD Radio – less choice / more noise! |date=2005-08-16 |website=Worldsupercaster.Blogspot.com |url=https://worldsupercaster.blogspot.com/2005/08/hd-radio-less-choice-more-noise.html |access-date=2008-12-31 |url-status=live |archive-url=https://web.archive.org/web/20061019011838/http://worldsupercaster.blogspot.com/2005/08/hd-radio-less-choice-more-noise.html |archive-date=2006-10-19 }}</ref><ref>{{cite web |title=Going digital – the end of radio as we know it |date=2002-01-03 |series=Feature |website=DIY Media (diymedia.net) |url=http://www.diymedia.net/feature/fdigital2.htm |access-date=2008-12-31 |url-status=dead |archive-url=https://web.archive.org/web/20090111041932/http://www.diymedia.net/feature/fdigital2.htm |archive-date=2009-01-11 }}</ref>

On 29&nbsp;January 2010, the U.S. FCC approved a [[report and order]] to voluntarily increase the maximum digital [[effective radiated power]] (ERP) to 4% of analog [[effective radiated power|ERP]] (−14&nbsp;dB[[carrier wave|c]]), up from the previous maximum of 1% (−20&nbsp;dBc).<ref>{{cite report |publisher=U.S. [[Federal Communications Commission]] |date=2010-01-29 |title=Digital power increase for FM stations approved |id=MM Docket No.&nbsp;99-235, DA&nbsp;10-208 |url=http://www.fcc.gov/fcc-bin/audio/DA-10-208A1.pdf |url-status=dead |access-date=2010-02-26 |archive-url=https://wayback.archive-it.org/all/20140523212426/http://www.fcc.gov/fcc-bin/audio/DA-10-208A1.pdf |archive-date=2014-05-23}}</ref> Individual stations may apply for up to 10% (−10&nbsp;dBc) if they can prove it will not cause harmful interference to any other station. If at least six verified complaints of ongoing [[RF interference]] to another station come from locations within the other station's licensed [[service contour|service geographic region]], the interfering station will be required to reduce to the next level down of 4%, 2% (−17&nbsp;dB), or 1%, until the FCC finally determines that the interference has been satisfactorily reduced.<ref>{{cite news |first=Leslie |last=Stimson |date=2010-02-15 |title=FCC order lays out the steps |website=Radio World online (rwonline.com) |publisher=NewBay Media, LLC |place=New York, NY |url=http://www.rwonline.com/article/94652 |url-status=usurped |archive-url=https://archive.today/20120908201907/http://www.rwonline.com/article/94652 |archive-date=2012-09-08}}</ref> The station to which the interference is caused bears the [[Legal burden of proof|burden of proof]] and its associated expenses, rather than the station that causes the problem. For [[grandfather clause|grandfathered]] FM stations, which are allowed to remain over the limit for their [[list of broadcast station classes|broadcast class]], these numbers are relative to that lower limit rather than their actual power.

====Asymmetric sidebands====

In May 2025 the FCC confirmed it would permit asymmetric sideband levels to be used.<ref>{{cite web |title=FCC Now Accepting Asymmetric Digital FM Sidebands |url=https://www.radioworld.com/news-and-business/business-and-law/fcc-officially-oks-asymmetric-digital-fm-sidebands}}</ref>  The total power in the asymmetric side bands must not exceed that which would be permitted when the sidebands are symmetrical.  The use of asymmetrical sidebands can reduce interference to an adjacent FM channel.

==Comparison to other digital radio standards==

===HD versus DAB===
Some countries have implemented [[Digital Audio Broadcasting|Eureka-147 Digital Audio Broadcasting]] (DAB) or the newer [[DAB+]] version. DAB broadcasts a single multiplex that is approximately 1.5&nbsp;[[megahertz]] wide (≈1&nbsp;[[megabit per second]]). That multiplex is then subdivided into multiple digital streams of between 9~12&nbsp;programs (or stations). In contrast, HD FM requires 400&nbsp;[[kHz]] bandwidth – compatible with the 200&nbsp;kHz channel spacing traditionally used in the [[ITU Region|ITU Region 2]] (including the United States) – with capability of 300&nbsp;[[kilobit per second|kbit/s]] in digital-only mode.

The gradually phased out first generation [[Digital Audio Broadcasting|DAB]] uses the [[MPEG-1 Audio Layer II]] (MP2) audio codec which has less efficient compression than newer codecs. The typical bitrate for DAB stereo programs is 128&nbsp;kilobit per second or less and as a result most radio stations on DAB have a poorer sound quality than FM does under similar conditions.{{refn|name=Holm-2007-DAB-Lydkvalitetet|
{{cite report |last=Holm |first=Steve |year=2007 |title=Lydkvalitetet i DAB digitalradio |trans-title=The sound quality in DAB digital radio |type=research report |publisher=Digitale Utgivelser ved Universitetet i Oslo [Digital Releases from the [[University of Oslo]]] |lang=no |url=http://wo.uio.no/as/WebObjects/theses.woa/wa/these?WORKID=52348 |access-date=2009-01-03 |url-status=dead |archive-url=https://web.archive.org/web/20080501073857/http://wo.uio.no/as/WebObjects/theses.woa/wa/these?WORKID=52348 |archive-date=2008-05-01}} ([[Nynorsk|in Norwegian]]) with Summary (in [[English language|English]]).{{efn|name=Sammendrag|
Holm (2007)<ref name=Holm-2007-DAB-Lydkvalitetet/> ''The sound quality in DAB digital radio'', {{sc|Summary}} {{in lang|en}}:<br/>
This analysis of the audio quality of DAB has been made independently of the broadcasting companies and aims at balancing their information.
Through measurement of the audio signal and through informal listening, we have found that DAB suffers from several problems:<br/>
* The stereo image is smeared due to heavy use of joint stereo coding. Often the stereo image lacks focus and gives incorrect localization of instruments, in certain cases there is also incorrect balance between a vocalist and the background music.
* The treble cut-off frequency is usually as low as 14&nbsp;kHz and the result is a lack of brightness and a veiled sound stage. In particular young people will notice this degradation.
As young people are the target group for some of these stations, such as P3, this must be considered to be very undesirable.
The reason is that the bit rates for all the channels in the Norwegian DAB network today are much lower than what scientific evaluation of audio quality has recommended, i.e. lower than 192–256&nbsp;kbit/s which was projected when DAB was debated in Stortinget (Norwegian Parliament) in 1998.
When the capacity is fully utilized, stations with music in the [[Oslo]] area use these bit rates:<br/>
* Three stations use 160&nbsp;kbit/s with an audio quality similar to FM: P2, Alltid Klassisk1 and P4
* Twelve stations use 128&nbsp;kbit/s with lower quality than FM, incl. P1 and P3.
* Two stations transmit in mono at rates of 80 and 96&nbsp;kbit/s (Radio&nbsp;2 Digital Moox and NRK Barn2)
It would have been desirable to stop using 128&nbsp;kbit/s as the standard bit rate for music, and use 160&nbsp;bit/s instead. More demanding material should have the same quality as MP3 at 128&nbsp;kbit/s, i.e. 192&nbsp;kbit/s in DAB. As of today, there is not capacity to increase bit rates to these levels, so the DAB network has too low capacity with respect to requirements for decent audio quality.<br/>
The broadcast companies want us to make a choice between FM, with the best audio quality in stationary receivers, and DAB which is best in a car. Today this is an unnecessary choice as there are no technological problems in making a digital radio which is better than FM on all accounts:<br/>
* Reception without garbling in cars
* Capacity for all the stations one wants
* Audio with near-CD quality
:::::::: — Steve Holm (2007)<ref name=Holm-2007-DAB-Lydkvalitetet/>
}}
}} Many DAB stations also broadcast in mono. In contrast, DAB+ uses the newer [[AAC+]] codec and HD FM uses a codec based upon the [[MPEG-4]] [[HE-AAC|HE]]-[[LC-AAC|AAC]] standard.

Before DAB+ was introduced, DAB's inefficient compression led in some cases to "downgrading" stations from [[stereophonic]] to [[monaural]], in order to include more channels in the limited 1&nbsp;[[Mbit/s]] bandwidth.<ref>{{cite news |title=Mono is the new stereo on national DAB |website=Digital Radio Tech (digitalradiotech.co.uk) |url=http://www.digitalradiotech.co.uk/articles/Mono-is-the-new-stereo-on-national-DAB.php |access-date=2009-01-03 |date=2006-12-15}}</ref>

Digital radio allows for more stations and less susceptibility for disturbances in the signal. In the United States, however, other than HD&nbsp;Radio,  digital broadcast technologies, such as DAB+, have not been approved for use on either the [[Band II|VHF band II]] ([[FM broadcast band|FM]]) or [[medium wave]] band.

DAB better suits national broadcasting networks that provide several stations as is common in Europe, whereas HD is more appropriate for individual stations.

===HD versus DRM===
[[Digital Radio Mondiale]] (DRM&nbsp;30) is a system designed primarily for [[shortwave radios|shortwave]], [[medium wave]], and [[longwave]] broadcasting with compatible radios already available for sale. DRM&nbsp;30 is similar to HD AM, in that each station is broadcast via channels spaced 10&nbsp;[[kHz]] (or 9&nbsp;kHz in some regions) on frequencies up to 30&nbsp;[[MHz]]. The two standards also share the same basic modulation scheme (COFDM), and HD AM uses a proprietary codec. DRM&nbsp;30 operates with [[xHE-AAC]], historically with any of a number of codecs, including AAC, Opus, and [[Harmonic Vector Excitation Coding|HVXC]]. The receiver synchronization and data coding are quite different between HD AM and DRM&nbsp;30. As of 2015 there are several radio chipsets available which can decode AM, FM, [[Digital Audio Broadcasting|DAB]], DRM&nbsp;30 and [[DRM+]], and HD AM and HD FM.

Similar to HD AM, [[Digital Radio Mondiale|DRM]] allows either hybrid digital-analog broadcasts or pure digital broadcasts, DRM allows broadcasters to use multiple options:
* Hybrid mode (digital/analog) - 10&nbsp;kHz analog plus 5&nbsp;kHz digital bandwidth allows 5–16&nbsp;[[kilobit per second|kbit/s]] data rate;
* 10&nbsp;kHz digital-only bandwidth confined to ±5&nbsp;kHz of the channel center allows 12–35&nbsp;kbit/s;
* 20&nbsp;kHz digital-only bandwidth using ±10&nbsp;kHz (including half of the adjacent channels) allows 24–72&nbsp;kbit/s.

On the medium wave, actual DRM bit rates vary depending on day versus night transmission ([[groundwave]] versus [[skywave]]) and the amount of bits dedicated for error correction (signal robustness).

Although DRM offers a growth path for [[AM broadcasting|AM broadcasters]], it shares some issues with HD Radio in the AM:
* Shorter broadcast distance in hybrid mode compared to an analog [[AM expanded band|AM]] signal
* Interference with adjacent channels when using the 20&nbsp;[[kHz]] mode though in all-digital mode the signal fits inside the designated [[channel mask]].

[[DRM+]], a different system based upon the same principles of HD&nbsp;Radio on the FM band, but can be implemented in all the [[VHF]] bands (''[[band I|1]]'', ''[[Band II#Radio|2]]'', and ''[[Band III#Radio|3]]''),<ref>{{cite web|url=http://www.drm-radio-kl.eu/symposium2010/symposium2010en.htm|title=Symposium DRM+ im VHF-Band III in Kaiserslautern|website=www.drm-radio-kl.eu|access-date=19 April 2018}}</ref> either as a hybrid analog-digital or digital only broadcast, but with 0.1&nbsp;MHz digital-only bandwidth, it allows 186.3&nbsp;kbit/s data rate<ref>{{cite web | title= DRM Introduction and Implementation Guide | publisher=DRM Consortium | date=13 September 2013 | url=http://www.drm.org/wp-content/uploads/2013/09/DRM-guide-artwork-9-2013-1.pdf | pages=22}}</ref><ref>{{cite web | url=http://drm-forum.de/images/drm-forum/drm-workshop-2016/Use_of_DRMplus_in_the_FM_Band.pdf | title=Use of DRM+ in the FM Band 87.5-108MHz | pages=6 | first=Jens | last=Schroeder | date=April 2016 | publisher=Deutsches DRM-Forum }}</ref> (compared to HD FM with 0.4&nbsp;MHz allowing 300&nbsp;kbps.)

Digital Radio Mondiale is an [[open standard]]s system, albeit one that is subject to [[patent]]s and [[licensing]]. HD&nbsp;Radio is based upon the intellectual property of [[iBiquity|iBiquity Digital Co.]] / [[Xperi|Xperi Holding Co.]]  
The United States uses DRM for [[high frequency|HF]] / [[shortwave]] broadcasts.<ref>{{cite web |title=What's Happening with DRM in the United States? |date=2010-04-30 |series=DRM news |website=USDRM.com |url=http://www.usdrm.com/drm_news4.html |access-date=2021-08-12 |url-status=dead |archive-url=https://web.archive.org/web/20120426021131/http://www.usdrm.com/drm_news4.html |archive-date=2012-04-26}} — describes Digital Radio Mondiale use in the United States</ref>

==Acceptance and criticism==

===Awareness and coverage===
According to a survey dated 8&nbsp;August 2007 by Bridge Ratings, when asked the question, ''"Would you buy an HD Radio in the next two months?"'', only 1.0% responded ''"yes"''.<ref>{{cite news |title=HD Radio vs. internet radio: Which is radio's future? |date=2007-08-08 |publisher=Bridge Ratings |url=http://www.bridgeratings.com/press_08.08.07.HDvsInternet.htm |access-date=2009-01-03 |url-status=dead |archive-url=https://web.archive.org/web/20081216004432/http://www.bridgeratings.com/press_08.08.07.HDvsInternet.htm |archive-date=2008-12-16 }}</ref>

Some [[broadcast engineer]]s have expressed concern over the new HD system.<ref>{{cite web |last=Savage |first=Bob |title=End the radio engineering scourge that could mean doom to AM radio |publisher=Stop IBOC Now! |url=http://www.stopiboc.com/ |access-date=2016-07-03  |archive-url=https://web.archive.org/web/20110904032637/http://www.stopiboc.com/ |archive-date=2011-09-04}}</ref> A survey conducted in September&nbsp;2008 saw a small percentage of participants that confused HD Radio with [[satellite radio]].<ref>{{cite news |last=Saghir |first=Ryan |date=2008-09-12 |title=HD Radio awareness is up ... so what? |website=Orbitcast |url=http://www.orbitcast.com/archives/hd-radio-awareness-is-up-so-what.html |access-date=2009-01-03 |url-status=dead |archive-url=https://web.archive.org/web/20090104005750/http://www.orbitcast.com/archives/hd-radio-awareness-is-up-so-what.html |archive-date=2009-01-04 }}</ref>

Many first-generation HD Radios had insensitive receivers, which caused issues with sound quality. The HD Radio digital signal level is 10–20&nbsp;dB below the analog signal power of the station's transmitter. In addition, commentators have noted that the analog section of some receivers were inferior compared to older, analog-only models.<ref>{{cite web |last=Menta |first=Richard |date=2007-03-24 |title=HD Radio undermined by weak tuners |url=http://www.mp3newswire.net/stories/7002/hd-radio2.html |access-date=2009-01-03 |url-status=live |archive-url=https://web.archive.org/web/20081228111052/http://www.mp3newswire.net/stories/7002/hd-radio2.html |archive-date=2008-12-28 }}</ref>

However, since 2012, HD capable receiver adoption has significantly increased in most newer cars, and several aftermarket radio systems both for vehicles and home use contain HD Radio receivers and special features such as Full Artist Experience. iBiquity reports that 78% of all radio listening is done on stations that broadcast in HD.<ref>{{cite web |title=Stats banner |website=HD Digital Radio (hdradio.com) |type=image |url=http://hdradio.com/sites/default/files/stats-banner.png/ |access-date=2014-12-17 |url-status=dead |archive-url=https://web.archive.org/web/20150315162447/http://hdradio.com/sites/default/files/stats-banner.png |archive-date=2015-03-15}}</ref> There are an increasing number of stations switching to HD or adding subchannels compatible with digital radio, such as [[St. Cloud, Minnesota]], where many local radio outlets find a growing number of listeners tuning in to their HD signals, which in turn has benefited sales.<ref>{{cite news |title=Boon or bust, HD Radio alters Minnesota airwaves |date=21 February 2015 |newspaper=[[St. Cloud Times]] |url=http://www.sctimes.com/story/news/local/2015/02/21/boon-bust-hd-radio-comes-kasm-kvsc-stations-around-st-cloud-minnesota/23824175/}}</ref>

===Different format and compatibility standards===
Even though [[Digital Audio Broadcasting|DAB]] and [[Digital Radio Mondiale|DRM]] standards are open standards and predate HD&nbsp;Radio, HD receivers cannot be used to receive these stations when sold or moved overseas (with certain exceptions; there are HD stations in [[Sri Lanka]],<ref>{{cite web |title=Our technology |website=NETH‑FM (nethfm.com) |url=http://www.nethfm.com/site/our-technology.html |url-status=dead |archive-url=https://web.archive.org/web/20110714165459/http://www.nethfm.com/site/our-technology.html |archive-date=14 July 2011 |access-date=16 March 2011 }}</ref>{{update inline|date=March 2023|reason=No indication on the current website that it still broadcasts on the HD Radio system and on worlddab.com it claims that there are consultations to use DAB+ in the future.}} [[Thailand]], [[Taiwan]], [[Japan]], [[Romania]], and a few other countries).

DAB and DRM receivers cannot receive HD signals in the U.S. The HD system, which enables [[AM expanded band|AM]] and [[FM broadcast band|FM]] stations to upgrade to digital without changing frequencies, is a different digital broadcasting standard. The lack of a common standard means that HD receivers cannot receive DAB or DRM broadcasts from other countries, and vice versa, and that manufacturers must develop separate products for different countries, which typically are not dual-format.

Whereas the [[Advanced Audio Coding]] (AAC) family of codecs are publicly documented standards, the HDC codec exists only within the HD system, and is an [[iBiquity]] [[trade secret]].

Similarly DAB or DRM are open specifications, while iBiquity's HD specification is partly open, but mostly private.<ref>{{cite report |title=Petition for reconsideration of Jonathan E. Hardis |series=before U.S. FCC |date=2007-07-09 |publisher=U.S. [[Federal Communications Commission]] |url=http://gullfoss2.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6519550109 |access-date=2007-10-29}} {{Dead link|date=September 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

HD Radio does not use [[ATSC]], the standard for [[digital television in the United States]], and so fails to recover the former TV and FM radio compatibility enjoyed by TV channel&nbsp;6 broadcasters. In the days of analog television, the lowest sliver of the [[FM broadcast band]] (87.7–87.9&nbsp;[[MHz]]) overlapped with the FM audio carrier of U.S. analog television's channel&nbsp;6;{{Efn|
Former U.S. analog TV channel&nbsp;6 occupied the upper end of the lower [[VHF]] TV band, which impinged on the lowest two channels of the [[FM broadcast band]]. License frequencies were carefully assigned to avoid overlap with geographically adjacent [[VHF]] TV stations on analog channel&nbsp;6, and [[FM broadcasting|FM stations]] on 87.7 and 87.9&nbsp;[[MHz]].
}} because the [[NTSC]] [[analog television]] standard used conventional analog FM to modulate the audio carrier, the audio of television stations that broadcast on channel&nbsp;6 could be heard on most FM receivers. In earlier days of television and radio, several television stations exploited this overlap and [[Channel 6 radio stations in the United States|operated as radio stations]]. Full-powered television stations were [[Digital television transition in the United States|forced to cease their analog broadcast]]s in June&nbsp;2009, and low-powered stations ceased analog broadcasts by July&nbsp;2021. Because the digital television and all digital radio standards are incompatible, HD receivers are not able to receive digital TV signals on the 87.75&nbsp;[[MHz]] frequency, eliminating the former dual-medium compatibility of channel&nbsp;6 television stations. Current low-power [[ATSC 3.0]] [[Channel 6 radio stations in the United States|channel 6 stations that broadcast an audio carrier on 87.75]] do not have HD Radio.

===Reduced-quality concerns===
Promotion for HD&nbsp;Radio often fails to make clear that some of its features are mutually incompatible with other features. For example, the HD system has been described as "CD quality"; however, the HD system also allows [[multiplexing]] the data stream between two or more separate programs. A program utilizing one half or less of the data stream does not attain the higher audio quality of a single program allowed the full data stream. The FCC has declared
: "one [[free-to-air|free]] [[over-the-air programming|over-the-air]] digital stream [must be] of equal or greater quality than the station's existing analog signal".<ref>{{cite report |title=Second Report & Order (U.S. FCC) | date=2007-05-31 | url=http://fjallfoss.fcc.gov/edocs_public/attachmatch/FCC-07-33A1.pdf | access-date = 2007-10-29 }}</ref>

If the FCC disallows analog simulcasting, each station will have over 300&nbsp;[[kilobit per second|kbit/s]] bandwidth available, allowing for good stereo quality or even [[surround sound]] audio, together with multiple sub-channels, and to a lesser extent more freedom for low-power, personal FM transmitters, to pair modern [[smartphone]]s, [[computer]]s, and other devices to legacy analog&nbsp;FM receivers.

The broadcasting industry is seeking FCC approval on future HD receiver models, for [[conditional access]]; that is, enabling the extra subchannels to be available only by paid [[subscription]]. [[NDS Group|NDS]]{{efn|
[[NDS Group]] is a maker of digital media [[encryption]] technology.
}} has made a deal with [[iBiquity]] to provide HD Radio with an encrypted content-delivery system called "RadioGuard".<ref>{{cite news |first=Skip |last=Pizzi |date=2007-09-01 |title=Subscription radio gets real |website=Radio World online |url=http://www.rwonline.com/pages/s.0054/t.8141.html |access-date=2009-01-03 |url-status=usurped |archive-url=https://web.archive.org/web/20080905144902/http://www.rwonline.com/pages/s.0054/t.8141.html |archive-date=2008-09-05}}</ref> [[NDS Group|NDS]] claims that RadioGuard will "provide additional revenue-generating possibilities".

Mostly all existing FM receivers tuned to a channel broadcasting a HD signal are prone to increased noise on the analog signal, called "HD Radio self-noise", due to analog demodulation of the digital signal(s). In some high fidelity FM receivers in quality playback systems, this noise can be audible and irritating. Most all existing FM receivers will require modifications to the internal [[electronic filter|filter]]s or the addition of a post-detection filter to prevent degradation of the analog signal quality on stations broadcasting HD&nbsp;Radio.

===Reduced analog signal===
Radio stations are licensed in the United States to broadcast at a specific [[effective radiated power]] level. In 2008, [[NPR]] Labs did a study of predicted HD Radio operation if the digital power levels were increased to 10% of the maximum analog carrier power as is now allowed by the FCC under certain circumstances, and found the digital signal would increase [[RF interference]] on FM. However the boosted digital HD signal coverage would then exceed analog coverage, with 17% more population covered in vehicles but 17% less indoors.<ref>{{cite news |last=Behrens |first=Steve |date=2008-09-02 |title=More power for HD Radio, more buzz on analog |website=Current.org |url=http://www.current.org/tech/tech0815hdradio.shtml |access-date=2009-01-03 |url-status=dead |archive-url=https://web.archive.org/web/20081230020804/http://www.current.org/tech/tech0815hdradio.shtml |archive-date=2008-12-30 }}</ref>

===High costs===
The costs of installing the system, including fees, vary from station to station, according to the station's size and existing infrastructure. Typical costs are at least several tens of thousands of dollars at the outset{{efn|name=HFRadio-startup-costs|
HF&nbsp;Radio startup costs include transmitter, diplexer (or a new, separate [[radio antenna|antenna]] and [[feedline]]), and installation labor.
}} plus per-channel annual fees (3% of the station's annual revenue{{citation needed|date=February 2018}}) to be paid to Xperi for HD‑2 and HD‑3 (HD‑1 has no royalty charge). Large companies in larger [[media market]]s – such as [[iHeartRadio]] or [[Cumulus Broadcasting]] – can afford to implement the technology for their stations. However, [[community radio]] stations, both commercial and noncommercial, in many cases cannot afford the [[United States dollar|US$]]1,000 yearly Xperi fee assessed to [[LPFM]] stations. During mid-2010 a new generation of HD Radio broadcasting equipment was introduced, greatly lowering the startup costs{{efn|name=HFRadio-startup-costs}} of implementing the system.

HD Radio receivers cost anywhere from around [[United States dollar|US$]]50 to several hundred dollars, compared to regular FM radios which can sometimes even be found at [[dollar store]]s. 
Although costs have historically been higher for HD hardware, as adoption has increased, prices have been reduced, and receivers containing HD Radio are becoming more commonplace – especially as more stations broadcast in HD format.{{Citation needed|date=December 2018}}

===Power consumption===
{{self-contradictory|1=section|date=March 2023|reason=Digitizing broadcasting is supposed to increase efficiency and reduce costs whereas this uncited section contradicts this}}

Conventional [[frequency modulation|analog-only FM]] [[transmitter]]s normally operate with "[[Power amplifier classes#Class C|class&nbsp;C]]" [[RF power amplifier|amplifiers]], which are [[Amplifier figures of merit#Efficiency|efficient]], but not linear; HD Radio requires a different [[Power amplifier classes|amplifier class]]. A class&nbsp;C amplifier can operate with overall [[Amplifier figures of merit#Efficiency|transmitter efficiency]] higher than 70%.{{efn|
"[[Amplifier figures of merit#Efficiency|Transmitter efficiency]]" is actually the efficiency of the [[radio transmitter|transmitter's]] final-stage amplifier. It is the ratio of [[radio frequency|RF]] power put out by the transmitter divided by the [[electrical power]] it consumes. Efficiencies differ by [[Power amplifier classes|amplifier class]], ranging over all classes from 25% at the [[Power amplifier classes#Class A|worst-of-the-worst]], to 90% at the [[Power amplifier classes#Class C|best-of-the-best]].
}} Digital transmitters operate in one of the other amplifier classes – one that is close to linear, and linearity lowers the efficiency. A modern hybrid HD FM transmitter typically achieves 50~60% efficiency, whereas an HD digital-only FM transmitter should manage just 40~45%. The reduced efficiency causes significantly increased costs for electricity and for cooling.

==Programming==
Until 2013, the [[HD Digital Radio Alliance]],{{efn|
The [[HD Digital Radio Alliance]] is a [[consortium]] of major broadcasters such as [[American Broadcasting Company|ABC]], [[Columbia Broadcasting System|CBS]], and [[iHeartMedia]] (then known as [[Clear Channel Communications]]).
}} acted as a liaison for stations to choose unduplicated formats for the extra channels (HD‑2, HD‑3, etc.). Now, [[iBiquity]] works with the major owners of the stations to provide various additional choices for listeners, instead of having several stations independently deciding to create the same format. HD‑1 stations broadcast the same format as the regular [[FM broadcast band|FM]] (and some [[AM expanded band|AM]]) stations, and many of these stations offer one, two, or even three subchannels (designated HD‑2, HD‑3, HD‑4) to complement their main programming.

[[iHeartRadio]] is selling programming of several different [[music genre]]s to other competing stations, in addition to airing them on its own stations. Some stations are [[simulcast]]ing their local [[AM broadcasting|AM]] or [[LPFM|lower-power FM]] broadcasts on sister stations' HD‑2 or HD‑3 channels, such as [[KFNZ-FM]] in [[Kansas City, Missouri|Kansas City]] simulcasting 610&nbsp;[[AM expanded band|AM]] [[KFNZ (AM)|KFNZ]]'s programming on 96.5&nbsp;[[FM broadcast band|FM]]‑HD2. It is common practice to broadcast an older, discontinued format on HD‑2 channels; for example, with the recent disappearance of the [[smooth jazz]] format from the analog radio dial in many markets, stations such as [[WDZH|WDZH‑FM]] in [[Detroit|Detroit, Michigan]], (formerly WVMV), [[WFAN-FM]] in [[New York City]], and [[WNWV-FM]] in [[Cleveland, Ohio]], program smooth jazz on their HD‑2 or HD‑3 bands. Some HD‑2 or HD‑3 stations are even simulcasting [[sister station|sister]] [[AM broadcasting|AM stations]]. In [[St. Louis, Missouri|St.&nbsp;Louis]], for example, clear-channel [[KMOX|KMOX‑AM]] (1120&nbsp;[[kHz]] analog and HD) is simulcast on [[KEZK-FM]] 102.5&nbsp;[[FM broadcast band|FM]]‑HD3. [[KBCO|KBCO‑FM]] in [[Boulder, Colorado]], uses its HD‑2 channel to broadcast exclusive live recordings from their private recording studio. [[CBS Radio]] is implementing plans to introduce its more popular [[superstation]]s into distant markets ([[KROQ-FM]] into New York City, [[WFAN (AM)|WFAN‑AM]] into Florida, and [[KFRG-FM]] and [[KSON (FM)|KSCF‑FM]] into Los Angeles) via HD‑2 and HD‑3 channels.

On 8&nbsp;March 2009, [[CBS Radio]] inaugurated the first station with an HD4 subchannel, [[WJFK-FM]] in [[Washington, D.C.]], a [[sports radio]] station which also carries sister sports operations [[WJZ-FM]] from [[Baltimore]]; [[Philadelphia]]'s [[WTEL (AM)|WTEL‑AM]] and [[WIP-FM]]; and [[WFAN (AM)|WFAN‑AM]] from [[New York City|New York]].{{efn|
Note however, that at some point, the [[WJZ-FM]] simulcast changed to a simulcast of [[Dallas, Texas]], sister sports station [[KRLD-FM]].
}}<ref>{{cite news |title=WJFK launches first HD Radio "quadcast" |date=2010-03-08 |website=Radio Business Report / Television Business Report (rbr.com tvbr.com) |place=[[United States of America|U.S.]] [[Washington metropolitan area]] |url=http://www.rbr.com/radio/22071.html |access-date=2021-08-11 |url-status=dead |archive-url=https://web.archive.org/web/20100311015752/http://www.rbr.com/radio/22071.html |archive-date=2010-03-11 }}</ref> Since then numerous other channels have implemented HD‑4 subchannels as well, although with nearly 100% talk-based formats, because of the reduced audio quality. For example, [[KKLQ (FM)|KKLQ‑FM]] in Los Angeles operates an HD‑4 signal and aired The Mormon Channel which was 99% talk.<ref>{{cite web |title=Local HD Radio stations |website=HD Digital Radio (hdradio.com) |url=http://hdradio.com/stations/ |access-date=14 April 2018 |url-status=live |archive-url=https://web.archive.org/web/20171128043318/https://hdradio.com/stations |archive-date=28 November 2017}}</ref>

[[Public broadcasting|Public broadcasters]] are also embracing HD Radio. [[Minnesota Public Radio]] offers a few services: [[KNOW-FM]], the [[Minnesota Public Radio News|MPR News]] station in the [[Minneapolis–Saint Paul|Twin Cities]], offers music service [[Radio Heartland]] on 91.1&nbsp;[[FM broadcast band|FM]]‑HD2 and additional news programming called "[[BBC News]] and More" on 91.1&nbsp;[[FM broadcast band|FM]]‑HD3; [[KSJN-FM]], the classical [[Minnesota Public Radio|MPR]] station in the [[Minneapolis–Saint Paul|Twin Cities]], provides "[[Classical 24]]" service on 99.5&nbsp;[[FM broadcast band|FM]]‑HD2; and [[KCMP-FM]], on 89.3&nbsp;[[FM broadcast band|FM]] in the [[Minneapolis–Saint Paul|Twin Cities]], offers "Wonderground Radio", music for kids and their parents, on 89.3&nbsp;[[FM broadcast band|FM]]‑HD2.<ref>{{cite web |title=HD Radio |series=[[Minnesota Public Radio]] |website=publicradio.org |url=http://minnesota.publicradio.org/radio/hd_radio/ |access-date=14 April 2018 |url-status=live |archive-url=https://web.archive.org/web/20151007140034/http://minnesota.publicradio.org/radio/hd_radio/ |archive-date=7 October 2015}}</ref>

[[KPCC (radio station)|KPCC‑FM (Southern California Public Radio)]], heard on 89.3&nbsp;[[FM broadcast band|FM]] in [[Los Angeles]], offers a digital simulcast of its analog channel on 89.3&nbsp;[[FM broadcast band|FM]]‑HD1 and [[Minnesota Public Radio|MPR's]] music service [[KCMP-FM]] on 89.3&nbsp;[[FM broadcast band|FM]]‑HD2 in Los Angeles.<ref>{{cite press release |title=Listen |publisher=Southern California Public Radio |website=scpr.org |url=http://www.scpr.org/listen/ |access-date=14 April 2018 |url-status=live |archive-url=https://web.archive.org/web/20171005135806/http://www.scpr.org/listen |archive-date=5 October 2017}}</ref>

[[New York Public Radio]] in [[New York City]], [[WNYC (AM)]] and [[WNYC-FM]], ([[doing business as|d.b.a.]] [[WNYC]]) re-broadcasts a locally programmed, all-[[classical music|classical]] service from [[WQXR-FM]] called "[[WQXR-FM|Q2]]", on 93.9&nbsp;[[FM broadcast band|FM]]‑HD2. The service launched in March&nbsp;2006.<ref>{{cite web |title=HD Radio |website=wnyc.org |publisher=[[New York Public Radio]] |place=New York, NY |url=http://www.wnyc.org/hdradio/ |access-date=2010-01-29 |url-status=dead |archive-url=https://web.archive.org/web/20100226060727/http://www.wnyc.org/hdradio/ |archive-date=2010-02-26 }}</ref> On 8&nbsp;October 2009, the format was moved to [[WXNY-FM|WQXR‑HD2]] ([[WXNY-FM]]) on 105.9&nbsp;[[FM broadcast band|FM]] when [[WQXR-FM]] was acquired by [[New York Public Radio]] as part of a frequency swap with [[Univision Radio]] for their former frequency. The programming on the [[WNYC-FM]]‑HD2 channel now is a rebroadcast of [[WQXR-FM]], in order to give full coverage of [[WQXR-FM]] programming in some form, as the 105.9&nbsp;[[FM broadcast band|FM]] signal is weaker, and does not cover the whole area.

[[WMIL-FM]] in [[Milwaukee]] has offered an audio simulcast of [[Fox Broadcasting Company|Fox]] affiliate [[WITI (TV)|WITI‑TV]] on their HD‑3 subchannel since August&nbsp;2009 as part of a news and weather content agreement between iHeartRadio and [[WITI (TV)|WITI‑TV]]. This restored [[WITI (TV)|WITI‑TV's]] audio to the Milwaukee radio dial after a two-month break, following the digital transition; as a channel&nbsp;6 analog [[television station]] [[WITI (TV)|WITI‑TV]] exploited the [[NTSC#NTSC-M|87.7&nbsp;FM]] audio quirk as an advantage, in order to allow viewers to hear the station's newscasts and [[Fox Broadcasting Company|Fox]] programming on their car radios.

[[KYXY|KYXY‑FM]], operated by [[Columbia Broadcasting System|CBS]] in [[San Diego]] on 96.5&nbsp;[[FM broadcast band|FM]] and offers their HD‑2 channel as one of the few "subchannel only" independent Christian music based formats on HD Radio. Branded as "The Crossing", it is operated by [[Azusa Pacific University]].

College radio has also been impacted by HD Radio, stations such as [[WBJB-FM]] which is a public station on a college campus offer a student run station as one of the multicast channels. [[WKNC-FM]] in [[Raleigh, North Carolina|Raleigh, NC]], runs college radio programming on HD‑1 and HD‑2, and [[electronic dance music]] on [[WolfBytes Radio]] on [[WKNC-FM]]‑HD3.

Some commercial broadcasters also use their HD‑2 channels to broadcast the programming of noncommercial broadcasters. [[Bonneville International]] uses its HD‑2 and HD‑3 channels to broadcast [[Mormon Channel]] which is entirely noncommercial and operates solely as a public service from Bonneville's owner, [[The Church of Jesus Christ of Latter-day Saints]]. That network of eight HD‑2 and HD‑3 stations was launched on 18&nbsp;May 2009 and was fully functional within two weeks. Also, in Detroit, [[WMXD-FM]], an [[urban adult contemporary]] station, airs the [[contemporary Christian]] [[K-Love]] format on its HD‑2 band (the HD‑2 also feeds several analog translators around the metropolitan area – see below), due to an agreement between iHeartMedia and [[K-Love]] owner [[Educational Media Foundation]] (EMF), allowing [[Educational Media Foundation|EMF]] to program [[WMXD-FM]]'s HD‑2 channel. On a similar note, [[Los Angeles]]' [[KRRL]] 92.3&nbsp;[[FM broadcast band|FM]]‑HD3 signal rebroadcasts [[Educational Media Foundation|EMF]]'s [[Air1]], and in Santa Barbara [[KLSB]] 97.5&nbsp;[[FM broadcast band|FM]] airs [[K-Love]] on its primary frequency, and rebroadcasts [[Air1]] on HD‑2 (though neither supports "Artist Experience"). In St. Louis, Missouri, [[WFUN-FM|WFUN 96.3]]-HD2 rebroadcasts [[K297BI]] for the classical music station Classic 107.3.

In July&nbsp;2018, as part of a projected one year experiment, [[WWFD|WWFD‑AM]] in [[Frederick, Maryland]], became the first [[AM broadcasting|AM station]] to eliminate its analog transmissions and broadcast exclusively in digital.<ref>{{cite news |first=Emily M. |last=Reigart |date=16 July 2018 |title=Hubbard testing all-digital AM on WWFD |website=radioworld.com |url=https://www.radioworld.com/blog-1/hubbard-testing-all-digital-am-on-wwfd}}</ref>

===Translators===
Although FM [[broadcast translator]]s are prohibited from originating their own programming, the [[FCC]] allows translator stations to rebroadcast an HD Radio subchannel of the primary station it is assigned to, instead of the programming of that station's analog signal. Station owners in large markets have taken advantage of this rule to allow HD subchannels to be heard on analog FM, or take AM licenses with attached translators silent while continuing to feed the translator.

Translators can also be used in a more traditional manner to extend the range of the full content of the primary station, including the unmodified main signal and any HD Radio sub-channels, in areas where the station has poor coverage or reception. Translators are not required to transmit an HD Radio signal, and the vast majority of existing translators do not.

==Receivers==

===Automotive and home/professional===
[[File:KOST 103.5 HD Signal.jpg|thumb|HD‑1 signal on KOST 103.5&nbsp;[[FM broadcast band|FM]] in a Volkswagen RCD‑510 receiver]]
By 2012, there were several HD receivers available on the market. A basic model costs around [[United States dollar|US$]]50.

Automotive HD receiver manufacturers include:
{{div col |colwidth=10em |content=
* [[Alpine Electronics]]
* [[Clarion (car audio)|Clarion]]
* [[Delphi Corporation]]
* [[Directed Electronics]]
* [[Dual (brand)|Dual]]
* [[Harman International Industries|Harman]]
* Hirschmann Car Communication{{efn|Hirschmann Car Communication GmbH is now a subsidiary of TE Connectivity.}}
* Insignia ([[house brand]] for [[Best Buy]])
* [[Jensen Loudspeakers|Jensen]]
* [[JVC]]
* [[Kenwood Electronics|Kenwood]]
* [[Pioneer Electronics|Pioneer]]
* [[Sony]] {{small|(discontinued)}}
* [[Visteon]]
}}

Most car manufacturers offer HD receivers as audio packages in new cars, including:
{{div col |colwidth=8em |content=
* [[Ford Motor Company|Ford]]
* [[Honda]]
* [[Hyundai Motor Company|Hyundai]]
* [[Kia]]
* [[Mazda]]
* [[Nissan]]
* [[Subaru]]<ref>{{cite web |author=Juan@HDRadio [user name] |date=9 July 2013 |title=Subaru |series=Get a radio / new car |website=HD Digital Radio (hdradio.com) |url=http://hdradio.com/get-a-radio/new-car/subaru |access-date=14 April 2018 |url-status=dead |archive-url=https://web.archive.org/web/20180414234617/https://hdradio.com/get-a-radio/new-car/subaru |archive-date=14 April 2018}}</ref>
* [[Tesla Motors]]
* [[Toyota]]
* [[Volkswagen]]
}}

Home and office listening equipment is available from a number of companies in both component receiver and tabletop models, including:
{{div col |colwidth=12em |content=
* Audio Design Associates
* [[Boston Acoustics]] {{small|(discontinued)}}
* DaySequerra
* [[Denon]]
* DICE Electronics
* [[Directed Electronics]]
* Insignia
* [[Jensen Electronics]]
* [[LG]] {{small|(discontinued)}}
* [[Marantz]]
* [[McIntosh Laboratory|McIntosh]]
* [[Onkyo]]
* [[Polk Audio]]
* Radiosophy {{small|(discontinued)}}
* [[Radio Shack]] {{small|(discontinued)}}
* [[Rotel]]
* [[Sangean]]
* [[Sony]] {{small|(discontinued)}}
* [[TEAC Corporation|TEAC]]
* [[Visteon]]
* [[Yamaha Corporation|Yamaha]]
}}

===Portable===
[[File:Sangean HDR-14 HD Radio receiver.jpg|thumb|Sangean HDR‑14 portable receiver playing San Diego's [[KPBS-FM]] HD‑2 channel, "[[Classical 24]]".]]
Initially, portable HD receivers were not available due to the early chipsets either being too large for a small enclosure and / or needing too much power to be practical for a battery-operated device. However, in January&nbsp;2008 at the [[Consumer Electronics Show]] (CES) in [[Las Vegas]], [[iBiquity]] unveiled a prototype of a new portable receiver, roughly the size of a cigarette pack. Two companies made low-power chipsets for HD receivers:
* Samsung<ref>{{cite press release |title=DTS and iBiquity Digital Corp to make the drive better with HD Radio technology |year=2009 |publisher=DTS / iBiquity |website=ibiquity.com |url=http://www.ibiquity.com/press_room/news_releases/2009/1331 |access-date=14 April 2018 |url-status=live |archive-url=https://web.archive.org/web/20150403083259/http://www.ibiquity.com/press_room/news_releases/2009/1331 |archive-date=3 April 2015}}</ref>  
* SiPort<ref>{{cite web |title=Intel Mobile Modem Solutions |url=http://www.siport.com/ |access-date=2009-04-28 |url-status=live |archive-url=https://web.archive.org/web/20090425053457/http://www.siport.com/ |archive-date=2009-04-25 }}</ref>{{efn|
SiPort is a [[Santa Clara, California|Santa Clara, CA]], startup acquired by [[Intel]] in 2011.<ref>{{cite news |title=Intel acquired SiPort, maker of Digital Radio Silicon |website=abiresearch.com |url=http://www.abiresearch.com/blogs/intel-acquired-siport-maker-of-digital-radio-silicon/ |access-date=14 April 2018 |archive-date=7 July 2017 |archive-url=https://web.archive.org/web/20170707154155/https://www.abiresearch.com/blogs/intel-acquired-siport-maker-of-digital-radio-silicon/ |url-status=dead }}</ref>
}}

At least five companies made portable HD receivers:
* [[Coby Electronics Corporation]] produced the first HD portable – the Coby HDR‑700 portable HD receiver for both AM and FM.<ref>{{cite web |title=Coby HDR‑700 HD receiver manual |publisher=[[Coby Electronics Corporation]] |url=http://www.cobyusa.com/files/manuals/HDR700_MN.pdf |access-date=2011-02-12 |url-status=dead |archive-url=https://web.archive.org/web/20110708171854/http://www.cobyusa.com/files/manuals/HDR700_MN.pdf |archive-date=2011-07-08 }}</ref>
* Griffin Technology produced an HD receiver designed to plug into the dock connector of an [[Apple Inc.|Apple]] [[iPod]], or [[iPhone]], with tuning functionality provided via [[software]] through the device's [[multi-touch]] display. This product was discontinued.
* [[Best Buy]] started selling the Insignia NS‑HD01, a [[house brand]] portable unit on 12&nbsp;July 2009. It was the second portable HD receiver to come to the general market and featured [[FM broadcast band|FM]]‑only playback and a non-removable rechargeable battery which charges via [[mini USB]]. The Insignia unit sold in 2009 for around [[United States dollar|US$]]50 – the least expensive receiver available.<ref>{{cite news |first=Darren |last=Murph |url=https://www.engadget.com/2009/07/12/insignia-ns-hd01-first-ever-portable-hd-radio-on-sale-at-best-b/ |title=Insignia NS‑HD01: First-ever portable HD Radio on sale at Best Buy |publisher=Engadget |date=2009-07-12 |access-date=2009-07-12 |url-status=live |archive-url=https://web.archive.org/web/20090713195246/http://www.engadget.com/2009/07/12/insignia-ns-hd01-first-ever-portable-hd-radio-on-sale-at-best-b/ |archive-date=2009-07-13 }}</ref> [[Best Buy]] discontinued the NS‑HD01 model by September&nbsp;2019 in favor of the NS-HD02.
* [[Microsoft]] released the {{nowrap|[[Zune HD]]}} on 15&nbsp;September 2009. It included an HD receiver embedded in the media device.<ref>{{cite news |first=Joshua |last=Topolsky |date=2009-09-17 |title=Zune&nbsp;HD review by Engadget |publisher=Engadget |url=https://www.engadget.com/2009/09/17/zune-hd-review/ |access-date=2009-09-17 |url-status=live |archive-url=https://web.archive.org/web/20090922221816/http://www.engadget.com/2009/09/17/zune-hd-review |archive-date=2009-09-22}}</ref> The Zune&nbsp;HD was discontinued in November 2011 in favor of [[Windows Phone]]s.
* [[Sangean|Sangean Electronics]] produces multiple portable HD radios with AM and FM reception, like the Sangean HDR-14 portable receiver.

By 2012, [[iBiquity]] was trying to get HDR chipsets into [[mobile phone]]s.

==Footnotes==
{{notelist}}

==References==
{{reflist|25em}}

==External links==
* {{cite web  |title=HD Radio |type=official site |website=HD Digital Radio (hdradio.com) |url=http://www.hdradio.com/}}
* {{cite web |title=IBOC digital radio broadcasting for AM and FM radio broadcast stations |publisher=U.S. [[Federal Communications Commission]] |url=http://www.fcc.gov/mb/audio/digital/ |archive-url=https://web.archive.org/web/20070930033358/http://www.fcc.gov/mb/audio/digital/ |archive-date=2007-09-30}} — IBOC general information page
* {{cite web |title=NRSC standards |type=main page |url=http://www.nrscstandards.org/}} — Site with standards documents for the NRSC formats of HD Radio
* {{cite web |title=Canadian HD Radio stations |website=My HD Radio |url=http://www.myhdradio.ca/canadian-hd-radio-stations/ |access-date=22 September 2017 |archive-date=24 April 2018 |archive-url=https://web.archive.org/web/20180424234611/http://www.myhdradio.ca/canadian-hd-radio-stations/ |url-status=dead }}
<!-- These can be used as references as needed -->
* {{cite web |title=WOR transmitter tour |website=hawkins.pair.com |url=http://hawkins.pair.com/wor.html |access-date=21 May 2005 |archive-date=21 December 2016 |archive-url=https://web.archive.org/web/20161221071448/http://hawkins.pair.com/wor.html |url-status=dead }} — information on an early IBOC installation
* {{cite news |first=Mark |last=Ramsey |date=16 May 2005 |title=The premature death of HD Radio |website=Hear 2.0 |publisher=Mercury Radio Research |url=http://www.hear2.com/2005/05/the_premature_d.html |archive-url=https://web.archive.org/web/20070503194144/http://www.hear2.com/2005/05/the_premature_d.html |archive-date=2007-05-03}} — editorial discusses marketing challenges for HD Radio 
* {{cite AV media |first=Doug |last=Dingus |date=11 March 2005 |title=HD Radio, analog FM, MP3 and OGG audio samples |medium=MP3 and OGG audio clips |website=Open Geek (opengeek.blogspot.com) |url=https://opengeek.blogspot.com/2005/03/hd-radio-analog-fm-mp3-and-ogg-audio.html}} — audio samples of actual HD broadcasts

{{Audio broadcasting}}

{{DEFAULTSORT:HD Radio}}
[[Category:HD Radio| ]]
[[Category:Xperi]]
[[Category:Digital radio]]
[[Category:Broadcast engineering]]
[[Category:Articles containing video clips]]
[[Category:American inventions]]
[[Category:2002 introductions]]
[[Category:2002 establishments in the United States]]