Compatible Amplitude Modulation - Digital or CAM-D is a hybrid digital radio format for AM broadcasting , proposed by broadcast engineer Leonard R. Kahn .
92-481: The system is an in-band on-channel technology that uses the sidebands of any AM radio station . Analog information is still used up to a bandpass of about 7.5 kHz , with standard amplitude modulation . The missing treble information that AM normally lacks is then transmitted digitally beyond this. Audio mixing in the receiver then blends them back together. Unlike other IBOC technologies like iBiquity 's HD Radio , Kahn's apparently does not provide
184-784: A "fallback" condition where it reverts to a more robust 25 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 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 . FCC rules require that one channel be
276-419: A CD, and the digital signals sometimes interfere with adjacent analog AM band stations. (see § AM, below ). The AM hybrid mode ("MA1") uses 30 kHz of bandwidth (±15 kHz ), and overlaps adjacent channels on both sides of the station's assigned channel. Some nighttime listeners have expressed concern this design harms reception of adjacent channels with one formal complaint filed regarding
368-713: A comprehensive trial of HD Radio technology in December 2006. The aim of the trial was to assess the coverage potential of the HD Radio system and to make a recommendation on the suitability of the technology for adoption. The first HD Radio station in the Philippines began broadcasting on November 9, 2005. The Philippines National Telecommunications Commission finalized its rules for FM digital radio operations on November 11, 2007. An HD Radio trial began in Warsaw in 2006 in order to demonstrate
460-452: A digital signal where the C-QUAM system would put the analog stereo decoding information. Digital Radio Mondiale has had much more success in creating an AM system, and one that could be much less expensive to implement than any proprietary HD Radio system, although it requires new frequency. It is the only one to have been accepted mediumwave but also shortwave (and possibly longwave ) by
552-430: A direct path to all-digital transmissions , nor any multichannel capability . Its advantage, however, is that it takes up far less of the sidebands, thereby causing far less interference to adjacent channels , hence the " Compatible " in the name. Interference has affected HD Radio on AM, along with its (like CAM-D) proprietary nature. Digital Radio Mondiale , commonly used in shortwave broadcasting, can use less,
644-824: A higher bitrate in Sirius satellite radio, see Digital Audio Radio Service ), but in August 2003 a switch to HDC (based-upon ACC) was made to rectify these problems. HDC has been customized for IBOC, and it is also likely that the patent rights and royalties for every transmitter and receiver can be retained longer by creating a more proprietary system. Digital Radio Mondiale is also developing an IBOC system, likely to be used worldwide with AM shortwave radio, and possibly with broadcast AM and FM. Neither of those have been approved yet for ITU region 2 (the Americas). Both AM and FM IBOC signals cause interference to adjacent-channel stations, but not within
736-421: A more lifelike sound. A significant disparity between Ibiquity 's AM HD Radio and CAM-D is that of time diversity . Namely, HD Radio's AM broadcast scheme broadcasts two copies of the program offset by a few seconds, allowing signal to be briefly lost and maintain uninterrupted program audio (for example, driving under an overpass, multipath in urban areas, lightning, switching transients, etc.). . However, in
828-461: A multiplex request from WTLC . The FM hybrid digital / analog mode offers four options which can carry approximately 100, 112, 125, or 150 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 kbit/s rate, and enabling extra features like surround sound. Like AM , purely-digital FM provides
920-693: A poorer sound quality than FM does under similar conditions. 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 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 Mbit/s bandwidth. Digital radio, such as DAB, DAB+, and HD FM 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
1012-625: A radio station can run between $ 100,000 and $ 200,000. Receiver manufacturers who include HD Radio pay a royalty, 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
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#17328691197451104-579: A receiver that requires a substantially different architecture for CAM-D will require special circuitry that will increase its cost. This is similar to HD Radio and other digital radio services. Since they all require new circuitry, inevitably, the price of manufacture will increase. This price will likely begin to decrease once the technology becomes proven. Since all new broadcast radios are moving to full digital formats that decode with nearly identical hardware ( XM , Sirius , HD Radio (in digital mode), Digital Audio Broadcasting , Digital Radio Mondiale ) in
1196-440: 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
1288-562: 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 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
1380-559: A survey dated 8 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" . Some broadcast engineers have expressed concern over the new HD system. A survey conducted in September ;2008 saw a small percentage of participants that confused HD Radio with satellite radio . Many first-generation HD Radios had insensitive receivers, which caused issues with sound quality. The HD Radio digital signal level
1472-408: A transmitter that multiplexes them all into one ensemble with the same coverage area (though many FM stations are already diplexed in large cities such as New York). [1] A further concern to FM station operators was that AM stations could suddenly be in competition with the same high audio quality, although FM would still have the advantage of higher data rates (300 kbit/s versus 60 kbit/s in
1564-481: Is FMeXtra by Digital Radio Express, which instead uses subcarriers within the existing signal. This system was introduced more recently. The FMeXtra is compatible with HD Radio in hybrid mode, but not in all-digital mode, and with RBDS . The stereo subcarrier can be removed to make more space available for FMeXtra in the modulation baseband. However, the system is not compatible with other existing 67–92 kHz subcarriers which have mostly fallen into disuse. The system
1656-484: Is multiplexed on existing signals, thus avoiding re-allocation of the broadcast bands. IBOC relies on unused areas of the existing spectrum to send its signals. This is particularly useful in North America style FM, where channels are widely spaced at 200 kHz but use only about 50 kHz of that bandwidth for the audio signal. In most countries, FM channel spacing may be as close as 100 kHz, and on AM it
1748-570: Is 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 . It uses a modified discrete cosine transform (MDCT) audio data compression algorithm. 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. The cost of converting
1840-555: Is a trademark for a so-called in-band on-channel (IBOC) digital radio broadcast technology. HD radio generally simulcasts an existing analog radio station in digital format with less noise and with additional text information. HD Radio is used primarily by AM and FM radio stations in the United States, U.S. Virgin Islands, Canada, Mexico and the Philippines, with a few implementations outside North America. HD Radio transmits
1932-423: 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 kbit/s of capacity is available. High-fidelity audio requires only 48 kbit/s so there
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#17328691197452024-523: 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,
2116-939: Is currently testing HD Radio in Beijing in contemplation for acceptance in that country. Caracol Radio began testing of the HD Radio technology in both the AM and FM bands in early 2008. El Salvador will be choosing HD Radio as its digital radio standard. In September 2007 the European HD Radio Alliance (EHDRA) was formed by broadcasters and other interested groups to promote the adoption of HD Radio technology by European broadcasters, regulators and standards organizations. France began broadcasting an HD Radio signal in March 2006 and plans to multicast two or more channels. The radio stations that use IBOC HD in France are SIRTI and NRJ Group. The owner of
2208-829: Is far less expensive and less complicated to implement, needing only to be plugged into the existing exciter , and requiring no licensing fees. FMeXtra has generally all the user features of HD Radio, including multicast capability, the ability to broadcast several different audio programs simultaneously. It uses the aacPlus (HE-AAC) codec. FMeXtra can restrict listening with conditional access and encryption . Digital Radio Mondiale allows for simultaneous transmission of multiple data streams alongside an audio signal. The DRM mode for VHF provides bandwidths from between 35 kbit/s to 185 kbit/s and up to four simultaneous data streams, allowing 5.1 surround DVD quality audio to be broadcast alongside other multimedia content - images, video or HTML content are typical examples. While it
2300-422: Is not backwards compatible with existing FM receiver equipment, with broadcasts digitally encoded using HE-AAC or xHE-AAC , this ability to operate within the internationally agreed FM spectrum of 88-108 MHz makes DRM a viable candidate for future adoption if countries begin to eliminate their analog broadcasts. iBiquity also created a mediumwave HD Radio system for AM, which is the only system approved by
2392-658: Is now widespread in dense urban markets like Toronto , Vancouver and Ottawa , with some use on the AM band as well. Initial testing of the HD Radio system commenced in Prague in February 2007. In China, Hunan Broadcasting Company started FMeXtra transmissions in Changsha in April 2007, and plans to put others throughout the Hunan province. SARFT (State Administration for Radio, Film and Television)
2484-412: Is occupied by TV channels 7 to 13 and the amateur radio 1.25 meter (222 MHz) band. The stations currently occupying that spectrum did not wish to give up their space, since VHF offers several benefits over UHF: relatively lower power, long distance propagation (up to 100 miles (160 km) with a rooftop antenna), and a longer wavelength that is more robust and less affected by interference. In Canada,
2576-815: Is only 10 kHz. While these all offer some room for additional digital broadcasts, most attention on IBOC is in the FM band in North American systems; in Europe and many other countries, entirely new bands were allocated for all-digital systems. Digital radio standards generally allow multiple program channels to be multiplexed into a single digital stream. In North American FM, this normally allows two or three high-fidelity signals combined in one channel, or one high-fidelity signal plus several additional channels at medium-fidelity levels that are much higher quality than AM. For even greater capacity, some existing subcarriers can be taken off
2668-552: Is said to work with a wider variety of existing transmitters, which is a selling point for smaller broadcasters with limited budgets. The price of the CAM-D hardware is $ 65,600 as of July 1, 2007. CAM-D is said to add high-frequency program information digitally transmitted and then overlaid onto the existing low- to mid-frequency analog program. This provides enhanced fidelity that under adequate analog signal conditions may allow AM stations to transmit music and other program content with
2760-579: Is the only digital technology approved by the FCC for digital AM and FM broadcasting in the US. Over 60 different HD Radio receivers are on sale in over 12,000 stores nationwide, including Apple, Best Buy, Target, and Wal-Mart. As of May 2007, FMeXtra is on several dozen stations. Several hundred stations belonging to the Idea Bank consortium will also have FMeXtra installed. [2] HD Radio HD Radio ( HDR )
2852-526: Is well suited to national broadcasting networks that provide several stations as is common in Europe, whereas HD is more appropriate for individual stations. Digital Radio Mondiale (DRM 30) is a system designed primarily for shortwave and medium wave broadcasting with compatible radios already available for sale. DRM 30 is similar to HD AM, 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
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2944-426: 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 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
3036-407: 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 ratio of signal strength to each other so as not to cause destructive interference at any given location where they may be received. HD Radio supports a service called "Artist Experience" in which
3128-555: The Canadian Radio-Television and Telecommunications Commission (CRTC) and Canadian Broadcasting Corporation (CBC) have also looked at the use of HD Radio, given its gradual progress in the neighbouring U.S. The CBC began HD Radio testing in September 2006, focusing on transmissions from Toronto and Peterborough, Ontario . The CRTC has since revised its policy on digital radio to allow HD Radio operations. Use of HD Radio
3220-608: The International Telecommunication Union (ITU) for use in regions I and III, but not yet in region II, the Americas . The HD Radio system has also been approved by International Telecommunication Union. CAM-D is yet another method, though it is more of an extension of the current system. Developed by AM stereo pioneer Leonard R. Kahn , It encodes the treble on very small digital sidebands which do not cause interference to adjacent channels, and mixes it back with
3312-592: The VHF bands ( 1 , 2 , and 3 ), either as a hybrid analog-digital or digital only broadcast, but with 0.1 MHz digital-only bandwidth, it allows 186.3 kbit/s data rate (compared to HD FM with 0.4 MHz allowing 300 kbps.) Digital Radio Mondiale is an open standards system, albeit one that is subject to patents and licensing . HD Radio is based upon the intellectual property of iBiquity Digital Co. / Xperi Holding Co. The United States uses DRM for HF / shortwave broadcasts. According to
3404-430: 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. 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
3496-470: The 200 kHz channel spacing traditionally used in the United States – with capability of 300 kbit/s in digital-only 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 stereo programs is 128 kilobit per second|kbit/s or less and as a result most radio stations on DAB have
3588-635: The Canadian Radio-television and Telecommunications Commission (CRTC) is continuing to follow the analog standard, so the channels remain unavailable there as well. HD Radio testing has been authorized in Canada, as well as other countries around the world. There was also concern that AM and FM stations' branding, using their current frequencies, would be lost to new channel numbers, though virtual channels such as on digital television would eliminate this. Also, several competing stations would have to share
3680-582: The Eureka-147 standard called DAB+ has been implemented. Using the more efficient high quality MPEG-4 CODEC HE-AAC v2, this compression method allows the DAB+ system to carry more channels or have better sound quality at the same bit rate as the original DAB system. It is the DAB+ implementation which will be under consideration for new station designs and not the earlier DAB scheme using the MUSICAM CODEC. The DAB+ system
3772-510: The Federal Communications Commission for digital AM broadcasting in the United States. The HD Radio system employs use of injected digital sidebands above and below the audible portion of the analog audio on the primary carrier. This system also phase modulates the carrier in quadrature and injects more digital information on this phase-modulated portion of the carrier. It is based on the principle of AM stereo where it puts
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3864-493: The HD Radio standard) due to greater bandwidth (100 kHz versus 10 kHz). The most significant advantage for IBOC is its relative ease of implementation. Existing analog radios are not rendered obsolete and the consumer and industry may transition to digital at a rational pace. In addition, the technology infrastructure is in place: most major broadcast equipment manufacturers are implementing IBOC technology and 60+ receiver manufacturers are selling IBOC reception devices. In
3956-425: The HD signal can revert to a more robust 20 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 CD quality audio and offers reduction of both interference and static. However, the data rates in HD Radio are substantially lower than from
4048-455: The HD ;Radio technology under the same banner as DTS 's eponymous theater surround sound systems. The HD Radio technology and trademarks were subsequently acquired by Xperi Holding Corporation in 2016. HD Radio is one of several digital radio standards which are generally incompatible with each other: By May 2018, iBiquity Digital Co. claimed its HD Radio technology
4140-629: The National Metrology Institute (Inmetro) was done and the Digital Radio Consultative Council concluded that HD Radio and DRM do not meet the same analog transmission coverage with 20db less power. New trials are expected to occur before any decision about the Brazilian Digital Radio standard. Brazil is considering for adoption Digital Radio Mondiale or HD Radio. After having L-band DAB for several years,
4232-580: The U.S. FCC increase the permissible FM IBOC power from 1% (currently) to a maximum of 10% of the analog power. On January 29, 2010, the FCC approved the request. In addition, tropospheric ducting and e-skip can reduce the range of the digital signal, as well as the analog. IBOC digital radios using iBiquity's standard are being marketed under the brand "HD Radio" to highlight the purported quality of reception. As of June 2008, over 60 different receiver models have been made, and stations have received blanket (no longer individual and experimental) authorization from
4324-470: The U.S. FCC to transmit in a multiplexed multichannel mode on FM. Originally, the use of HD Radio transmission on AM was limited to daytime only, and not allowed at night due to potential problems with skywave radio propagation. The FCC lifted this restriction in early 2007. DRM, however, is being used across Europe on shortwave, which is entirely AM skywave, without issue. With the proper receiver, many of those stations can be heard in North America as well, sans
4416-408: 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 , 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. Digital information
4508-536: The UK, Denmark, Norway and Switzerland, which are the leading countries with regard to implementing DAB, the first-generation MPEG-1 Audio Layer II (MP2) codec stereo radio stations on DAB have a lower sound-quality than FM, prompting a number of complaints. The typical bandwidth for DAB programs is only 128 kbit/s using the first generation CODEC, the less-robust MP2 standard which requires at least double that rate to be considered near-CD quality. An updated version of
4600-660: The US. Grupo Imagen commenced HD Radio transmissions on XHDL-FM and XEDA-FM as well as Instituto Mexicano de la Radio on XHIMR-FM, XHIMER-FM and XHOF-FM in Mexico City in June 2012. HD Radio transmission in Auckland, New Zealand was started on October 19, 2005. The frequency of IBOC HD radio is 106.1 MHz. The transmitter is located at Skytower. Following successful testing, the Radio Broadcasters Association (RBA) initiated
4692-544: The United Kingdom and many other countries have chosen the Eureka 147 standard of digital audio broadcasting (DAB) for creating a digital radio service, the United States has selected IBOC technology for its digital AM and FM stations. The band commonly used for terrestrial DAB is part of VHF band III, which does not suffer from L-band's significant line-of-sight problems. However, it is not available in North America since that span
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#17328691197454784-561: The air to provide additional bandwidth in the modulation baseband . On FM for instance, this might mean removing stereo from the analog signal, relying on the digital signal to provide stereo where desired, thus making room for another digital channel. Due to the reduced bandwidth in AM, IBOC is incompatible with analog stereo, although that is rarely implemented, and additional channels are limited to highly compressed voice such as traffic and weather . Eventually, stations can go from digital/analog-hybrid mode to all-digital, by eliminating
4876-475: The allotted ±100 kHz FM channel. This creates potential interference issues with adjacent channels. This is the most widely used system, with approximately 1,560 stations transmitting HD radio in the US, plus over 800 new multicast channels (as of Jan 2010). There is a one-time license fee to iBiquity Digital, for the use of its intellectual property, as well as costs for new equipment which range from $ 50,000 to $ 100,000 US (2010) per station. The other system
4968-432: 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. North American FM channels are spaced 200 kHz apart. An HD broadcast station will not generally cause interference to any analog station within its 1 mV/m service contour –
5060-406: The analog baseband. Unlike the other two, it is not intended to be capable of multichannel, opting for quality over quantity. Unlike the HD system iBiquity calls "hybrid digital" the CAM-D system truly is a direct hybrid of both analog and digital. Some engineers believe that CAM-D may be compatible with analog AM stereo with the right engineering. Critics of CAM-D point to several drawbacks: While
5152-580: The analog signal, thus taking a full 400 kHz of spectrum. In extended hybrid mode, the analog signal is restricted to ±100 kHz . Extended primary sidebands are added to the main primary sidebands using the extra ±30 kHz of spectrum created by restricting the analog signal. Extended hybrid provides up to approximately 50 kbit/s additional capacity. Any existing subcarrier services (usually at 92 kHz and 67 kHz ) that must be shut down to use extended hybrid can be restored through use of digital subchannels . However, this requires
5244-637: The analog signal. HD Radio technology was tested in 2004 with initial trials in Buenos Aires. Further testing of the technology began in early 2007. Government broadcaster BETAR began broadcasting HD Radio on their 100.0 MHz frequency on 9 November 2016 from their Agargaon site in Dhaka. The transmission uses a 10 kW GatesAir system. The 100.0 MHz carries programs from BBC World Service amongst others. HD 1, 2, 3 and 4 are configured. A second transmission will also have HD radio added on 88.8 MHz from
5336-629: 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% (−14 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 translators , 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
5428-529: The baseband monophonic audio. On FM there are three methods of IBOC broadcasting in use, primarily in the United States . The first, and only, digital technology approved for use on AM and FM broadcast frequencies by the Federal Communications Commission in the United States, is the proprietary HD Radio system developed by iBiquity Digital Corporation, which transmits energy beyond
5520-671: The broadcasts, more than 10,000 HD Radio receivers were installed in buses. The first FM HD Radio broadcasts in Kyiv went on the air in October 2006 on two FM stations operated by the First Ukrainian Radio Group. Voice of Vietnam (VOV) commenced AM and FM HD Radio transmissions in Hanoi in June, 2008 including multicasting, in anticipation of making HD Radio technology a standard. As of June 2008, more than 1,700 HD Radio stations were broadcasting 2,432 HD Radio channels. HD Radio technology
5612-428: The center frequency. This interference, which is audible mainly on analog radios, was one of the reasons Citadel Communications pulled night broadcasts of their AM HD station's signals. CAM-D does not produce interference on any channels 10 kHz or more from the center frequency. CAM-D is a system that is applicable to medium wave and possibly shortwave transmission. Since receivers are designed for multiple bands,
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#17328691197455704-558: 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 stands for "hybrid digital," not "high definition." 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. The term "on channel"
5796-568: The field, HD Radio, at a distance from the transmitter, is still not immune to the aspects of the AM dial such as those below. A substantial problem of analog AM transmission is that it is subject to poor signal-to-noise ratio due to radio frequency noise from man-made and natural sources, such as fluorescent lamps, motors, switches and lightning. Simply adding high frequency information does not produce high fidelity . HD Radio signals on AM, however, use more bandwidth signal wise and often create "hash" on surrounding frequencies, up to 30 kHz from
5888-401: 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 than HD Radio, digital broadcast technologies, such as DAB+, have not been approved for use on either the VHF band II ( FM ) or medium wave band. DAB
5980-500: The highest baseband modulating frequency (around 60 kHz when RBDS is used). Only 15 kHz of the baseband bandwidth is used by analog monaural audio (baseband), with the remainder used for stereo , 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 ±130 kHz of analog bandwidth. The primary main digital sidebands extend ±70 kHz on either side of
6072-414: The interfering station will be required to reduce to the next level down of 4%, 2% (−17 dB), or 1%, until the FCC finally determines that the interference has been satisfactorily reduced. 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
6164-463: 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 dB, the potential exists to cause the degradation of the second-adjacent analog signals within its 1 mV/m contour . On 29 January 2010, the U.S. FCC approved a report and order to voluntarily increase
6256-520: The limit for their broadcast class , these numbers are relative to that lower limit rather than their actual power. Some countries have implemented Eureka-147 Digital Audio Broadcasting (DAB) or the newer DAB+ version. DAB broadcasts a single multiplex that is approximately 1.5 megahertz wide (≈1 megabit per second ). That multiplex is then subdivided into multiple digital streams of between 9~12 programs (or stations). In contrast, HD FM requires 400 kHz bandwidth – compatible with
6348-556: The long term, the overhead of analog circuitry will cause a cost penalty to implement the technology in future radios. In-band on-channel In-band on-channel ( IBOC ) is a hybrid method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency . The name refers to the new digital signals being broadcast in the same AM or FM band (in-band), and associated with an existing radio channel (on-channel). By utilizing additional digital subcarriers or sidebands , digital information
6440-573: The matter: WYSL owner Bob Savage against WBZ in Boston. The capacity of a 30 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 Hz, thus achieving moderate quality on the bandwidth -tight AM band . The HD Radio AM hybrid mode offers two options which can carry approximately 40~60 kbit/s of data, with most AM digital stations defaulting to
6532-451: The maximum digital effective radiated power (ERP) to 4% of analog ERP (−14 dB c ), up from the previous maximum of 1% (−20 dBc). Individual stations may apply for up to 10% (−10 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 geographic region ,
6624-441: 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 broadcasters , unfortunately it shares many of the same flaws as DAB and HD AM: DRM+ , a different system based upon the same principles of HD Radio on the FM band, but can be implemented in all
6716-430: The more-robust 40 kbit/s mode, which features redundancy (same data is broadcast twice). The digital radio signal received on a conventional AM receiver tuned to an adjacent channel sounds like white noise – the sound of a "hiss" , or a large waterfall, or a strong, steady wind through a dense forest canopy , or similar. All-digital AM ("MA3") allows for two modes: "Enhanced" and "core-only". When
6808-489: The primary digital carrier. Four stations have operated as all-digital / digital-only broadcasters: 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). In October 2020, the FCC concluded from WWFD 's experiments: The FCC requires stations that wish to multiplex their digital AM signals to request and receive permission to do so; in early 2020 it rejected
6900-563: The public, and with Leonard Kahn's death, interest in CAM-D vanished and those stations using it turned it off, not seeing any financial return. KCI (Kahn Communications, Inc., the company that invented CAM-D) uses as one of its main selling points that some older transmitters are not directly upgradeable to transmit HD Radio. It is true that older transmitters may lack the transmission purity needed to support HD Radio's digital transmission standard, but more recent transmitters are more likely to be capable of upgrading to transmit HD Radio. CAM-D
6992-554: The purpose of discussing the rollout of the technology in Europe. Radio Sunshine has now switched to DAB+ due to the high penetration of DAB+ and lack of interest in HD Radio. DAB+ penetration in Switzerland has now reached 99.5% as of 2018. HD Radio transmission in Thailand was started in April 2006. Radio of Thailand had created a public IBOC HD radio network targeting mass transit commuters in Thailand's capital of Bangkok. To receive
7084-420: 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. However, all-digital AM lacks the analog signal for fallback when the signal is too weak for the receiver to decode
7176-403: 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 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,
7268-574: The same basic modulation scheme (COFDM), and HD AM uses a proprietary codec. DRM 30 operates with xHE-AAC , historically with any of a number of codecs, including AAC, Opus, and HVXC . The receiver synchronization and data coding are quite different between HD AM and DRM 30. As of 2015 there are several radio chipsets available which can decode AM, FM, DAB , DRM 30 and DRM+ , and HD AM and HD FM. Similar to HD AM, DRM allows either hybrid digital-analog broadcasts or pure digital broadcasts, DRM allows broadcasters to use multiple options: On
7360-399: 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. Stations can transmit HD through their existing antennas using a diplexer , as on 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 auxiliary , provided it
7452-526: The same site. Trial and tests of HD Radio technology began in Sarajevo in March 2007. HD Radio and DRM trials in Brazil started in the mid 2000s. No regular HD Radio or DRM transmissions are allowed in Brazil as the digital radio standard in that country is not yet defined. One or two year experimental licenses were given to some Broadcasters. A joint study by the government (Ministry of Communications and ANATEL) and
7544-405: The same, or more bandwidth as AM, to provide high quality audio. Digital Radio Mondiale requires digital detection circuitry not present in conventional AM radios to decode programming. Special CAM-D receivers provide the benefit of better frequency response and a slow auxiliary data channel for display of station ID, programming titles, etc. Receivers that could decode CAM-D were not available to
7636-443: The sparse allocation of FM broadcast channels in North America; in Europe, stations are more tightly spaced. iBiquity developed HD 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. It is officially known as NRSC‑5, with the latest version being NRSC‑5‑E. iBiquity was acquired by DTS in September 2015 bringing
7728-413: The station's interference-free protected contours designated by the U.S. Federal Communications Commission (FCC). It has led to derogatory terms such as IBAC (In-band adjacent-channel) and IBUZ (since the interference sounds like a buzz.) The range of a station on an HD Radio receiver is somewhat less than its analog signal. In June 2008, a group of US broadcasters and equipment manufacturers requested that
7820-635: The technology to local radio stations. WPRM FM is the first station in San Juan, Puerto Rico (part of the US) to adopt HD Radio, in April 2005. WRTU in San Juan has also commenced broadcasting in HD Radio technology in 2007. FM testing sponsored by Radio Sunshine and Ruoss AG began in Lucerne in April 2006. HD Radio operations in Switzerland continue and are spotlighted each year during “HD Radio Days”, an annual gathering in Lucerne of European broadcasters and manufacturers for
7912-399: 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. Since 2016, newer HD Radios support Bluetooth and Emergency Alert System (EAS) alerts in which
8004-412: The transmission of traffic, weather alerts, 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. FM stereo stations typically require up to 280 kilohertz of spectrum . The bandwidth of an FM signal is found by doubling the sum of the peak deviation (usually 75 kHz ) and
8096-461: 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
8188-536: The transmitter is Towercast. The frequency of IBOC HD radio is 88.2 MHz. In May 2006, The Towercast group added a single channel of digital audio on 93.9 MHz. Radio Regenbogen began HD Radio operations on 102.8 MHz in Heidelberg on December 3, 2007 pursuant to government testing authority. Forum Radio Jaringan Indonesia had tested IBOC HD transmission from March 2006 to May 2006. The IBOC HD station in Jakarta
8280-640: Was Delta FM (99.1 MHz). In April 2006, Radio Sangkakala (in Surabaya), the first AM HD radio station in Asia, went on the air on 1062 kHz. Radio Jamaica began operating full-time with both HD Radio AM and FM signals in the city of Kingston in 2008. All Mexican radio stations within 320 km of the U.S. border are allowed to transmit their programs on the AM and FM bands utilizing HD Radio technology. Approximately six Mexican AM and FM stations are already operating with HD Radio technology along Mexico’s border area with
8372-503: Was coordinated and developed by the World DAB Forum, formed in 1997 from the old organization. It gives the Eureka-147 system a similar quality per bit rate as the IBOC system and hence (arguably) a better sound quality than FM. AM IBOC in the United States still faces some serious technological challenges, including nighttime interference with other stations. iBiquity initially used an audio compression system known as PAC (also used at
8464-950: Was used by more than 3,500 individual services, mostly in the United States. This compares with more than 2,200 services operating with the DAB system . A 400 kHz wide channel is required for HD FM analog-digital hybrid transmission, making its adoption problematic outside of North America. In the United States, FM channels are spaced 200 kHz apart as opposed to 100 kHz elsewhere. Furthermore, long-standing FCC licensing practice, dating from when receivers had poor adjacent-channel selectivity, assigns stations in geographically overlapping or adjacent coverage areas to channels separated by (at least) 400 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. Outside
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