HD RADIO is a trademarked term for iBiquity 's in-band on-channel
(IBOC) digital radio technology used by AM and FM radio stations to
transmit audio and data by using a digital signal embedded
"on-frequency" immediately above and below a station's standard analog
signal , providing the means to listen to the same program in either
HD (digital radio with less noise) or as a standard broadcast (analog
radio with standard sound quality). The HD format also provides the
means for a single radio station to simultaneously broadcast one or
more different programs in addition to the program being transmitted
on the radio station's analog channel.
It was selected by the
U.S. Federal Communications Commission (FCC)
in 2002 as a digital audio broadcasting method for the United States,
and is the only digital system approved by the FCC for digital AM/FM
broadcasts in the United States. It is officially known as NRSC-5,
with the latest version being NRSC-5-C. Other digital radio systems
Digital Audio Broadcasting (DAB) (Eureka 147),
Digital Radio Mondiale (DRM30 and
DRM+ configurations), and Compatible
HD Radio does allow for an all-digital mode, this system
currently is used by some AM and FM radio stations to simulcast both
digital and analog audio within the same channel (a hybridized
digital-analog signal) as well as to add new FM channels and text
HD Radio broadcasting's content is currently
subscription -free, listeners must purchase new receivers in order to
receive the digital portion of the signal.
As of May 2009, there were more stations in the world on the air with
HD Radio technology than any other digital radio technology. More than
1,700 stations covering approximately 84% of the
United States are
broadcasting with this technology, and more than 1,000 HD2 and HD3
multicast channels are on the air. According to iBiquity's website,
the "HD" is simply a brand name and has no meaning. There is no
connection with high-definition television (HDTV), although like
digital television the
HD Radio specification provides enhanced
capabilities over the analog format, such as 5.1 surround sound.
The FCC has not indicated any intent to force off analog radio
broadcasts as it has with analog television broadcasts, as 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
Radio receiver. In addition, there are many more analog AM/FM radio
receivers than there were analog televisions, and many of these are
car stereos or portable units that cannot be upgraded.
* 1 Overview
* 1.1 AM
* 1.2 FM
* 1.2.1 Artist Experience
* 1.2.2 EAS Alerts
* 1.2.3 Bandwidth and power
* 2 Comparison to other digital radio standards
HD Radio versus DAB
HD Radio versus DRM
* 3 Acceptance and criticism
* 3.1 Awareness and coverage
* 3.1.1 Different format and compatibility standards
* 3.1.2 Reduced-quality concerns
* 3.1.3 Reduced analog signal
* 3.1.4 High costs
* 4 Programming
* 4.1 Translators
* 5 Receivers
* 5.1 Automotive and home/professional
* 5.2 Portable
* 5.3 Open Source Software-Defined Receiver (SDR)
* 6 References
* 7 External links
Digital information is transmitted using
OFDM with an audio
compression algorithm called HDC (
High-Definition Coding ). (HDC is a
proprietary codec based upon, but incompatible with, the MPEG-4
HD Radio 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. The cost of converting a radio
station can run between $100,000 and $200,000. Receiver manufacturers
pay a royalty.
If the primary digital signal (HD-1) is lost the
HD Radio receiver
will revert to the analog signal, thereby providing seamless operation
between the newer and older transmission methods. The extra HD-2 and
HD-3 streams are not simulcast on analog, causing the sound to
drop-out or "skip" when digital reception degrades (similar to digital
television drop-outs). Alternatively the
HD Radio signal can revert to
a more-robust 20 kilobit per second stream, though the sound is
reduced to AM-like quality.
Datacasting is also possible, with
metadata providing song titles or artist information.
iBiquity Digital claims that the system approaches CD quality audio
and offers reduction of both interference and static; however, some
listeners have complained of increased interference on the analog AM
band (see AM, below).
An example of information displayed by an AM HD station locking.
Sending pure digital data through the approximately 20 kilohertz AM
channel is roughly equivalent to sending data through two 33 kbit/s
analog telephone lines, thus limiting the maximum throughput possible.
By using spectral band replication the HDC+SBR codec is able to
simulate the recreation of sounds up to 15,000 Hz, thus achieving
moderate quality on the bandwidth -tight AM band. The
HD Radio AM
hybrid mode offers two options which can carry approximately 40 or 60
kbit/s of data, but most AM digital stations default to the
more-robust 40 kbit/s mode which features redundancy (same signal
HD Radio also provides a pure digital mode, which lacks an analog
signal for fallback and instead reverts to a 20 kbit/s signal during
times of poor reception. The pure digital mode transmissions will stay
within the AM station's channel instead of spilling into the channels
next to the station transmitting "HD radio" as the hybrid
(digital-analog) stations do.
The AM version of
HD Radio technology uses the 20 kHz channel (+/- 10
kHz), and overlaps 5 kHz into the opposite sideband of the adjacent
channel on both sides. When operating in pure digital mode, the AM HD
Radio signal fits inside a standard 20 kHz channel (20-40 kbit/s) or
an extended 30 kHz channel (40-60 kbit/s), at the discretion of the
station manager. As AM radio stations are spaced at 9 kHz (Europe) or
10 kHz (Americas) intervals, much of the digital information overlaps
adjacent channels when in hybrid mode. Some nighttime listeners have
expressed concern this design harms reception of adjacent channels
with one formal complaint filed regarding the matter:
WYSL owner Bob
Savage against WBZ in Boston.
The digital radio signal received on a conventional AM receiver tuned
to an adjacent channel sounds like a large waterfall or similar white
noise-like hiss, as can be heard in the audio soundclip referenced in
the previous sentence.
Play media HD radio DX during a band opening HD Radio
Transmitter Spectrum of FM broadcast station without
Spectrum of FM broadcast station with
HD Radio Play media
HD Radio EAS Test using
The FM hybrid digital/analog mode offers four options which can carry
approximately 100, 112, 125, or 150 kbit/s of lossy data depending
upon the station manager's power budget and desired range of signal.
HD Radio also provides several pure digital modes with up to 300
kbit/s bitrate, and enabling extra features like surround sound. Like
AM, pure digital FM provides a "fallback " condition where it reverts
to a more robust 25 kbit/s signal.
FM stations have the option to subdivide their datastream into
sub-channels (e.g., 88.1 HD1, HD2, HD3) of varying audio quality. The
multiple services are similar to the digital subchannels 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 subchannels to provide more variety to listeners.
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 kbit/s.
Where the digital signal fails, the analog signal is used as a
fallback for the main digital channel (normally HD1), requiring
synchronization of the two. Current FCC rules require that one channel
be a simulcast of the analog signal. In some cases, particularly
during tropospheric ducting events, an
HD Radio receiver will lock on
to the digital sidebands of a distant station, even though there is a
much stronger local analog-only station on the 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. (Station identification is sent by voice, or as RBDS
data, but not all stations use RBDS.) The listener can possibly turn
HD reception off (to listen to the local station, or avoid random
flipping between the two stations), or 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 HD radios can process digital
signals. The digital processing of analog signals in an HD radio
delays them also. The resulting unmistakable "reverb" or echo effect
from playing radios of both types in the same room or house can be
annoying. It is more noticeable with simple voice transmission than
with complex musical program content. (Multiple HD receivers of the
same make and model, or multiple analog receivers in the same room or
house, will not cause noticeable echo.)
Stations can transmit
HD Radio through their existing antennas using
a diplexer as on AM, or are permitted by the FCC to use a separate
antenna at the same location, or at a site licensed as an analog
auxiliary , provided it is within a certain distance and height
referenced to the analog main signal. This limitation assures that the
two have about the same broadcast range , and that they maintain the
proper ratio of signal strength to each other so as not to cause
destructive interference with each other at any given location where
they may be received.
HD Radio supports a service called Artist Experience in which the
transmission of album art, logos and other artwork can be displayed on
the radio. 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
Since 2016, newer HD radios support
Bluetooth and EAS alerts in
which the transmission of traffic, weather, AMBER and security alerts
can be displayed on the radio. As with Artist Experience, emergency
alerts are displayed at the station's discretion and requires extra
Bandwidth And Power
Currently, FM stations in the
United States and
Canada are licensed
to carry 100 kilohertz of bandwidth , requiring approximately 200
kilohertz of spectrum . Only 15 kHz of the modulation bandwidth is
used by analog monaural audio (baseband), with the remainder used for
RBDS , paging , radio reading service , rental to other
customers , or as a transmitter/studio link for in-house telemetry .
In regular hybrid mode a station has its full ±100 kHz of analog
bandwidth and adds an extra ±30 kHz guard band and ±70 kHz for its
digital signals, thus taking a full 400 kHz of width. FM stations also
have the option to discontinue existing subcarrier services (usually
at 92 kHz and 67 kHz) in order to carry extended HD Radio, though such
services can be restored through use of the digital subchannels that
are then made available. However, this requires the replacement of all
related equipment both for the broadcasters and all of the receivers
that use the discontinued services.
The ratio of power of the analog signal to the digital signal was
initially standardized at 100:1 (-20 dBc), making the digital signal
1% of the analog carrier power. Unlike with subcarriers, where the
total baseband modulation is reduced, there is no reduction to the
analog carrier power . The National Association of Broadcasters (NAB)
requested a 10 dB (10×) increase 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 dB or fourfold increase to 4% (−14dBc or 25:1).
National Public Radio
National Public Radio was opposed to any increase because it is likely
to increase interference to their member stations, particularly to
their broadcast translators , which are secondary and therefore left
unprotected from such interference. Other broadcasters are also
opposed (or indifferent), as 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 Radio on FM will increase
interference between different stations even though
HD Radio at the
10% power level fits within the FCC spectral mask. North American FM
channels are spaced 200 kHz apart. An HD
Radio station will not
generally cause interference to any analog station within its 1 mV/m
service contour , the limit above which the FCC protects most
stations. However, the IBOC signal resides within the analog signal of
the first-adjacent station. With the proposed power increase of 10 dB,
the potential exists to cause the degradation of the second-adjacent
analog signals within its 1 mV/m service contour .
On January 29, 2010, the U.S. FCC approved a report and order to
voluntarily increase the maximum digital effective radiated power
(ERP) to 4% of analog ERP (−14 dBc ), up from the previous maximum
of 1% (−20dBc). Individual stations may apply for up to 10%
(−10dBc) if they can prove it will not cause destructive
interference to any other station. If at least six verified complaints
RF interference to another station come from locations
within the other station's service contour , the interfering station
will be required to reduce to the next level down of 4%, 2% (−17
dB), or 1%, until the FCC makes a final determination. The station to
which the interference is caused bears the burden of proof and its
associated expenses, rather than the station that causes the problem.
For grandfathered FM stations which are allowed to remain over the
limit for their class , these numbers are relative to that lower limit
rather than their actual power.
COMPARISON TO OTHER DIGITAL RADIO STANDARDS
HD RADIO VERSUS DAB
Some countries have implemented Eureka-147 Digital Audio Broadcasting
(DAB) or its successor DAB+. DAB broadcasts a single station that is
approximately 1500 kilohertz wide (~1000 kilobits per second). That
station is then subdivided into multiple digital streams of between 9
and 12 programs. In contrast FM
HD Radio is assigned to the
traditional 200 kilohertz-wide channels, with capability of 300 kbit/s
in pure digital mode.
The first generation DAB uses the
MPEG-1 Audio Layer II (MP2) audio
codec which has less efficient compression than newer codecs. The
typical bitrate for DAB programs is only 128 kbit/s and as a result
most radio stations on DAB have a lower sound quality than FM does
under optimal circumstances. In contrast, DAB+ uses the newer AAC+
codec and FM
HD Radio uses a codec based upon the
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 1000 kbit/s bandwidth.
Digital radio, such as DAB, DAB+ and FM HD radio currently often have
smaller coverage of markets as compared to analog FM, radios are more
expensive, and reception inside vehicles and buildings may be poor,
depending on the frequencies used.
HD Radio shares most of these same
flaws (see criticisms below ). On the other hand, digital radio allows
for more stations and less susceptibility for disturbances in the
signal. In the United States, however, other digital broadcast
technologies than HD radio (such as DAB+) have not been approved for
use on either the FM or AM band.
HD RADIO VERSUS DRM
Digital Radio Mondiale (DRM 30) is a system designed primarily for
shortwave radio with compatible radios already available for sale. DRM
30 is similar to AM
HD Radio in that each station is broadcast via
channels spaced 10 kHz (or 9 kHz in some regions) on frequencies up to
30 MHz. The two standards also share the same basic modulation scheme
(COFDM), and AM
HD Radio uses a proprietary codec. DRM 30 operates
with any of a number of codecs, including AAC, Opus and HVXC. The
receiver synchronization and data coding are quite different between
HD Radio and DRM 30. As of 2015 there are several radio chipsets
available which can decode AM, FM, ()
DRM+ and DRM 30.
Similar to HD Radio, DRM allows either hybrid digital-analog
broadcasts or pure digital broadcasts, DRM allows broadcasters to use
* Hybrid mode (digital/analog) - 10 kHz analog plus 5 kHz digital
bandwidth allows 5-16 kbit/s data rate;
* 10 kHz digital-only bandwidth confined to +/- 5 kHz of the channel
center allows 12-35 kbit/s;
* 20 kHz digital-only bandwidth using +/- 10 kHz (including half of
the adjacent channels) allows 24-72 kbit/s.
DRM+ , a different system based upon the same principles, operates in
the VHF band with 100 kHz digital-only bandwidth which allows 700
kbit/s data rate.
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). For AM stations DRM offers a
growth path for broadcasters. Unfortunately DRM shares many of the
same flaws as DAB and
HD Radio technology: the hybrid mode has shorter
broadcast distance compared to an analog AM signal; poor reception
inside vehicles and buildings; and interference with adjacent channels
when using the 20 kHz mode though in all-digital mode the signal fits
inside the designated channel mask .
Digital Radio Mondiale is an open standards system.
HD Radio is based
upon the intellectual property of iBiquity Digital Corporation. The
United States utilizes DRM for HF or "Shortwave" broadcasts.
ACCEPTANCE AND CRITICISM
AWARENESS AND COVERAGE
According to a survey dated August 8, 2007 by Bridge Ratings, when
asked the question, "Would you buy an HD radio in the next two
months?" 1.0% responded "yes". Some broadcast engineers have
expressed concern over the new system. A survey conducted in
September 2008 saw a small percentage of participants that confused HD
radio with satellite radio .
HD Radio tuners had insensitive tuners, which
caused issues with reception quality. The
HD Radio signal is 10 to 20
dB below a station's analog signal. In addition it has been noted that
the analog section of some tuners displays inferior reception
capabilities compared to older non-digital models.
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. 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
Different Format And Compatibility Standards
Even though DAB and DRM standards are open-standards and pre-date HD
HD Radio receivers cannot be used to receive these stations
when sold or moved overseas (with certain exceptions; there are HD
Radio stations in Sri Lanka, Thailand, Taiwan, Japan, Romania and a
few other countries). DAB and DRM receivers cannot receive HD Radio
signals in the US. The
HD Radio system, which enables AM and FM
stations to upgrade to digital without changing frequencies, is a
different digital broadcasting standard. The lack of a common standard
means that HD Radios cannot receive DAB format broadcasts of other
countries and vice versa, and that manufacturers must develop separate
products for different countries, which typically are not dual-format.
Whereas the AAC (
Advanced Audio Coding ) family of codecs are publicly
documented standards, the HDC codec exists only within the HD Radio
system, and is an iBiquity trade secret . Similarly DRM and DAB are
open specifications, while iBiquity's
HD Radio specification is partly
open but mostly private.
HD Radio does not use
ATSC , the standard for digital television in
United States . In the days of analog television, the low end of
the FM broadcast band (87.7 to 87.9 MHz) overlapped with the audio
subcarrier of analog television's channel 6, which allowed the audio
of television stations that broadcast on that channel to be heard on
most FM radios. In earlier days of television and radio, several
television stations exploited this overlap and operated as radio
stations (a process that still continues with some low-powered
stations, which are still allowed to broadcast in analog for the time
being). Full-powered television stations were forced to cease analog
broadcasting in June 2009, with low-powered stations scheduled to
cease analog broadcasting by September 2015. Because the digital
television and digital radio standards are incompatible with each
other, HD radios are not able to receive digital TV signals on the
87.7 frequency, eliminating the antiquated dual-medium compatibility
of channel 6 television stations.
HD Radio does not always make clear that some of its
capabilities are mutually incompatible with other of its capabilities.
For example, the FM system has been described as "CD quality;"
however, the FM 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 over-the-air digital stream of equal or greater quality than the
station’s existing analog signal". (If the FCC discontinues analog
simulcasting, each station will have over 300 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 personal FM transmitters to pair modern smartphones ,
computers and other devices to legacy analog FM receivers.)
The broadcasting industry is seeking FCC approval for conditional
access , that is, enabling the extra programs to be available only by
paid subscription (on future models of HD Radio). NDS , a maker of
digital media encryption technology, has a deal with iBiquity to
HD Radio with an encrypted content-delivery system called
RadioGuard. NDS claims that RadioGuard will "provide additional
A few existing FM tuners tuned to a channel broadcasting an HD Radio
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 tuners in quality playback systems
this noise can be audible and irritating. A few existing FM tuners
might require major internal modifications to the internal filters ()
or the addition of a post-detection filter () may be required to
prevent degradation of the analog signal quality on stations
broadcasting with HD Radio.
Reduced Analog Signal
Radio stations are licensed in the
United States to broadcast at a
specific effective radiated power level.
NPR Labs recently did a study
of predicted HD radio operation if power levels were increased to 10%
of maximum 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.
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 (including transmitter, diplexer or
antenna/feedline , and labor), plus per-channel annual fees (3% of
revenue) to be paid to iBiquity for HD-2 and HD-3 (HD-1 does not have
any royalty charge). Large companies in larger media markets (such as
Cumulus Broadcasting ) can afford to implement the
technology for their stations. However, community radio stations, both
commercial and noncommercial, cannot. During mid-2010 a new generation
HD Radio broadcasting equipment was introduced greatly lowering the
technical costs of implementing the system.
HD Radio receivers cost anywhere from around $ 50 to several
hundred dollars, compared to regular FM radios which can sometimes
even be found at dollar stores . Although costs have historically been
HD Radio hardware, as adoption increases, prices are
lowering and receivers containing
HD Radio are becoming more
commonplace, especially as more radio stations broadcast in HD Radio.
Until 2013, the HD Digital Radio Alliance , a consortium of major
owners such as ABC, CBS, and iHeartMedia (then known as Clear Channel
Communications), acted as a liaison for stations to choose
unduplicated formats for the extra channels (HD2, HD3, 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. HD1
stations broadcast the same format as the regular FM (and some AM)
stations, and many of these stations offer one, two, or even three
subchannels (designated HD2, HD3, HD4) to complement their main
iHeartRadio is selling programming of several different music genres
to other competing stations, in addition to airing them on its own
stations. Some stations are simulcasting their local AM or lower-power
FM broadcasts on sister stations' HD2 or HD3 channels, such as KMBZ-FM
in Kansas City simulcasting 610 KCSP 's programming on 96.5-HD2. It is
common practice to broadcast an older, discontinued format on HD2
channels; for example, with the recent disappearance of the smooth
jazz format from the analog radio dial in many markets, stations such
Detroit, Michigan (formerly WVMV),
WFAN-FM in New York City
Cleveland, Ohio program smooth jazz on their HD2 or HD3
bands. Some HD2 or HD3 stations are even simulcasting sister AM
stations. In St. Louis, Missouri for example, clear-channel
(1120 kHz analog and HD) is simulcast on KEZK FM 102.5 HD3.
Boulder, Colorado uses its HD2 channel to broadcast exclusive live
recordings from their private recording studio.
CBS Radio is
implementing plans to introduce its more popular superstations into
distant markets (
KROQ-FM into New York City,
WFAN into Florida, and
KSCF into Los Angeles) via HD2 and HD3 channels.
On March 8, 2009,
CBS Radio inaugurated the first station with an HD4
Washington, DC , a sports radio station which
also carries sister sports operations
Philadelphia 's WTEL and WIP ; and
WFAN from New York (though at some
WJZ-FM simulcast was replaced with a simulcast of Dallas ,
Texas sister sports station
KRLD-FM ). Since then numerous other
channels have implemented HD4 subchannels as well, although with
nearly 100% talk-based formats because of the reduced audio quality.
For example, KSWD in
Los Angeles operates an HD4 signal and airs The
Mormon Channel which is 99% talk.
Public broadcasters are also embracing HD Radio. Minnesota Public
Radio offers a few services: KNOW , the MPR News station in the Twin
Cities , offers music service
Radio Heartland on 91.1 HD2 and
additional news programming called
BBC News and More on 91.1 HD3; KSJN
, the Classical MPR station in the Twin Cities, provides Classical 24
service on 99.5 HD2; and The Current , on 89.3 in the Twin Cities,
offers Wonderground Radio , music for kids and their parents, on 89.3
Southern California Public Radio , heard on 89.3 FM in
Los Angeles ,
offers a digital simulcast of its analog channel on 89.3 HD1 and MPR's
music service The Current on 89.3 HD2 in Los Angeles.
New York City
New York City broadcasts a locally programmed, all-classical
music service called Q2 , on 93.9 HD2. The service launched in March
2006. On October 8, 2009, the format was moved to WQXR -HD2 on 105.9
when WQXR was acquired by
WNYC as part of a frequency swap with
Univision Radio for their former frequency. The programming on the
WNYC HD2 channel now is a rebroadcast of WQXR in order to give full
coverage of WQXR programming in some form, as the 105.9 signal is
weaker and does not cover the whole area.
Milwaukee has offered an audio simulcast of Fox affiliate
WITI on their HD3 subchannel since August 2009 as part of a news and
weather content agreement between iHeartRadio and WITI. This restored
WITI's audio to the
Milwaukee radio dial after a two-month break after
the digital transition; as a Channel 6 analog television station WITI
exploited the 87.7 FM audio quirk as an advantage in order to allow
viewers to hear the station's newscasts and Fox programming on their
KYXY , operated by CBS in
San Diego on 96.5 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
Azusa Pacific University .
College radio has also been impacted by HD radio, stations such as
WBJB which is a public station on a college campus offer a student run
station as one of the multicast channels.
Some commercial broadcasters also use their HD2's to broadcast the
programming of noncommercial broadcasters. Bonneville International
uses its HD2 and HD3 channels to broadcast
Mormon Channel which is
entirely noncommercial and operates solely as a public service from
The Church of Jesus Christ of Latter-day Saints .
That network of eight HD2 and HD3 stations was launched on May 18,
2009 and was fully functional within two weeks. Also, in Detroit, WMXD
, an urban adult contemporary station, airs the contemporary Christian
K-Love format on its HD2 band (the HD2 also feeds several analog
translators around the metropolitan area—see below), due to an
agreement between iHeartMedia and
K-Love owner Educational Media
Foundation allowing EMF to program WMXD's HD2. On a similar note, Los
KRRL 92.3's HD3 signal rebroadcasts EMF's
Air1 and in Santa
KYGA 97.5, which airs
Air1 on its primary frequency,
K-Love on HD2 though neither one support 'Artist
Although broadcast translators are prohibited from originating their
own programming, the FCC has controversially allowed translator
stations to rebroadcast in standard analog FM the audio of an HD Radio
channel of the primary station the translator is assigned to. This
also allows station owners, who already usually own multiple stations
locally and nationally, to avoid the rulemaking process of changing
the table of allotments as would be needed to get a new
separately-licensed station, and to avoid exceeding
controlling-interest caps intended to prevent the excessive
concentration of media ownership . Such new translator stations can
LPFM stations from going on the air in the same footprint.
Translator stations are allowed greater broadcast range (via less
restrictive height and power limitations) than locally originated
LPFMs, so they may occupy a footprint in which several LPFMs might
have been licensed otherwise.
In addition to the controversial practice of converting the HD
Radio-only secondary channels of a primary station into analog FM in
areas where the primary station's signal can already readily be
received, 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, as is done at K202BD
Manti, Utah , which rebroadcasts both the analog and digital
Salt Lake City
Salt Lake City . In order to do this, HD Radio
may be passed along from the main station via a "bent pipe " setup,
where the translator simply makes a frequency shift of the entire
channel, often by heterodyning it through the use of an intermediate
frequency . This may require an increase in bandwidth in both the
amplifier and radio antenna if they are too narrowband to pass the
wider signal, meaning one or both would have to be replaced. Baseband
translators which use a separate receiver and transmitter require an
HD Radio transmitter, just as does the main station. Translators are
not required to pass through HD Radio, and the vast majority of
existing translators which repeat FM stations running hybrid HD Radio
signals do not repeat the
HD Radio part of the broadcast due to
technical limitations in equipment designed before the prominence of
AUTOMOTIVE AND HOME/PROFESSIONAL
By 2012, there were several
HD Radio receivers available on the
market. A basic model costs around $ 50.
The list of
HD Radio automotive receiver manufacturers includes
Alpine Electronics , Clarion ,
Delphi Corporation , Directed
Electronics , Dual , Harman ,
Insignia , Jensen ,
JVC , Kenwood ,
Sony , and
Most car manufacturers offer
HD Radio receivers as audio packages in
new cars, including
Tesla Motors ,
Toyota , and
Volkswagen . HD-1 signal on KOST
103.5 in a
Volkswagen RCD-510 receiver
Home and office listening equipment is currently available from
roughly a dozen companies, in both component tuner and tabletop
models, including Audio Design Associates, Boston Acoustics
(discontinued), DaySequerra ,
Denon , DICE Electronics, Directed
Jensen Electronics , LG (discontinued),
Marantz , McIntosh ,
Polk Audio , Radiosophy (discontinued),
Radio Shack ,
Sony , TEAC ,
Visteon , and
HD Radio receivers were unavailable due to the
early chipsets either being too large for a portable enclosure or
needing too much power to be practical for a battery-operated device.
However, in January 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 are currently
making low-power chipsets for
HD Radio receivers: Samsung, and Santa
Clara startup SiPort, acquired by
Intel in 2011.
The portable Coby HDR-700 unit receives AM HD and FM HD stations.
Griffin Technology produced an
HD Radio tuner designed to be plugged
into the dock connector of an Apple iPod or iPhone , with tuning
functionality provided via software through the device's multi-touch
display. This product is now discontinued.
On July 12, 2009,
Best Buy started selling a house brand portable
Insignia NS-HD01, which was the second portable
HD Radio to
come to the general market and features FM-only playback and a
non-removable rechargeable battery which charges via mini
USB . Coby
produced the first portable HD radio (HDR-700). The
Insignia unit sold
in 2009 for around $50, the least expensive receiver available, and
continues to be sold as of February 2015.
On September 15, 2009,
Microsoft released the
Zune HD , which
HD Radio receiver within the media device. The
Zune HD is
iBiquity was trying to get HDR chipsets into mobile phones by 2012.
OPEN SOURCE SOFTWARE-DEFINED RECEIVER (SDR)
As of June 10, 2017, a project hosted on
GitHub called _nrsc5_ has
been created to allow
HD Radio reception via _rtl-sdr_
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