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AM HD Radio Has Stalled. Now What?

Not many stations have it; others even turned it off. Where does it go next?

This is one in a series of articles Radio World has published over the past year exploring the business challenges and successes of AM radio.

With U.S. AM radio in general facing identity questions in the era of young consumers, iPods, MP3 players, Internet radio and other forms of media, so too toils digital AM.

Group heads of engineering and other industry observers say that digital AM is more technically challenging and expensive than FM. The flat, or even decreasing, number of AM stations embracing it certainly bears this out.

AM HD Radio, it seems, is the stepchild of the digital world.

Limited uptake

Proponents point to AM HD’s dramatic improvement in audio quality over that of analog. But several experts say that, at best, AM HD is having mixed success. Many even characterize it as struggling or not successful. Others, however, say it’s too early to tell what its future will be.

Only a core number of mostly big-wattage, large-market stations are broadcasting in AM digital; most of those transmit their digital signals only during the day, according to engineering observers. Many of the stations on-air with AM HD are owned by members of the HD Digital Radio Alliance.

A crew works on an AM project at 50 kW ESPN station WMVP Chicago, which airs HD Radio day and night. Glen Clark & Associates redesigned the antenna patterns in 2005 as well as the AM phasors for improved HD performance in 2007. In general, the AM digital rollout appears to be on pause; will it resume? Photo courtesy Glen Clark & Associates Reports of the number of AMs actually broadcasting in digital vary (see sidebar), but most of the U.S. HD Radio rollout has taken place on FM, as Radio World has reported over several years. That trend is confirmed by a BIA study this spring that counted 455 AMs with licenses to air digital. BIA found that 322 AMs were on the air with digital signals, about 16 percent of the total number (2,056) of digital stations; FMs account for the balance.

Programming strategies meanwhile continue to evolve and may have a bearing on uptake.

To boost listenership and expose their content to the younger audiences advertisers seek, owners increasingly have begun simulcasting AM station programming over FM translators; the FCC began allowing that practice about a year ago in an attempt to give AMs some relief. Some owners also are simulcasting their AMs on the multicast channels of their digital FMs, or on analog FM signals; the latest is Cox-owned WSB(AM), simulcasting on sister station WBTS(FM), Doraville, Ga.

According to one school of thought, when group owners pursue such strategies they feel less need to invest in HD Radio conversions for their AM outlets.

Many of AM HD’s problems mirror those of the overall band, a crowded slice of spectrum that’s prone to interference and coping with ever-increasing sources of man-made noise.

IBOC proponents say an all-digital mode — in which stations would turn off their analog signals and broadcast only in digital — would clear up interference issues that affect some AMs using the hybrid mode. But no one can say when or if such a time will come, especially lacking a federal mandate for digital radio. That’s an eventuality no one seems to think is likely anytime soon.

The poor economy of the past two years has contributed to AM HD’s stagnation as group owners concentrate on business basics like reducing their debt load and paying other bills.

Owners who have converted stations to digital appear especially focused on maintaining their FM digital systems; if they are not yet turning a profit via iTunes Tagging or traffic data, the thinking goes, those FM data services are at least bringing in incremental revenue that could someday lead to profit.

Yet HD Radio developer iBiquity Digital Corp. remains committed to a digital solution for AM. It has been working on a transmission scheme it hopes will answer the concerns of AM owners that haven’t converted or that are less than satisfied with the technology.

“We’re working on it,” President/CEO Bob Struble told Radio World recently.


AM HD is a touchy subject. Some corporate engineers at groups of various sizes did comment for this article; others did not answer requests; and several engineers declined to comment or could only do so anonymously. Therefore it’s difficult to glean what some broadcast groups that invested in AM HD Radio and in iBiquity itself think about the AM rollout.

IBiquity says some 286 AMs were airing digital as of mid-August. The company says approximately 50 others have turned the digital off due to technical problems or for other reasons (see sidebar) and another 50 or so licensees have yet to turn it on.

The majority of stations that turn it off, according to engineers interviewed for this article, do so because of blending problems between digital and analog in weak signal areas or because of interference to the host’s analog signal or to a neighboring station’s analog signal.

Citadel Broadcasting turned off the nighttime digital on its 10 AMs in the fall of 2007. At the time, Director of Corporate Engineering Martin Stabbert cited complaints from listeners and stations on adjacent channels, including both Citadel stations and others, in and outside the affected markets.

Citadel, a member of the HD Digital Radio Alliance, took part in “empirical testing” with iBiquity to see what could be done to mitigate nighttime interference. In 2008 and 2009, Radio World reported that iBiquity continued its AM testing. To date, there’s been no public word on the outcome of those tests.

Contacted recently to learn if the situation had changed, Stabbert said he could not comment about AM HD.

Journal Broadcast Group has two out of six AMs airing IBOC signals full-time; it has not turned any off. Andy Laird, vice president and chief technical officer for Journal — and a member of the National Radio Systems Committee who played a key in early NRSC IBOC testing — said, “Diligent installation has a large impact on ‘self’ interference. The antenna performance/load presented to the transmitter needs to meet or (hopefully) exceed iBiquity specifications.” He recommended that most AMs hire engineering consultants experienced with AM IBOC to evaluate and specify antenna upgrades to be performed.

His two AMs airing a digital signal are KFAQ in Tulsa and WTMJ in Milwaukee. KFAQ is 50 kW non-directional day, 50 kW directional night, and has had no complaints about interference, he said. WTMJ is 50 kW directional day and 10 kW directional night; the station has received no complaints concerning first-adjacent interference, while three listeners complained about an upper second-adjacent.

“In all three instances our signal level was 500 mV or greater and the desired second-adjacent station was substantially below 0.5 mV,” Laird said. “In all three cases, other radios owned by the complainant worked without issue; it was a specific [wideband] receiver that had the issue.”

A corporate DOE for a radio group owner with stations mainly in mid-size markets told Radio World recently his company shut off the digital on all of its AMs — completely, not just at night — due to the blending back and forth between analog and digital in areas where the digital signal is weak.

The blending irritated managers, he said. “It annoys listeners and drives them away.” He declined to say how many stations were involved because he did not want his company to be identifiable.

Blending can sound jarring if the time alignment between the analog and digital signals isn’t right, according to another DOE whose company has IBOC AMs on the air.

Critics long have claimed AM IBOC should be taken off the air because of interference to other stations from the digital sidebands. At least one corporate engineering executive agrees. And a third technical source, head of engineering for a major-market group owner, told Radio World, “Where AM IBOC was hoped to help most — nighttime coverage — it failed. I don’t see any reason to install it.”

Not always a nice blend

Some corporate engineers are more open about the issues with AM IBOC.

Of Greater Media’s five AMs, only one is licensed for HD; that digital station remains on-air, according to Vice President of Radio Engineering Milford Smith, who is chairman of the NRSC.

Smith believes AM IBOC is impressive in terms of fidelity and “freedom from typical AM interference,” especially on high-power stations. However, unless the listener is in a relatively strong signal area, “any perturbation of the signal, particularly by overhead metallic objects,” like power lines or overpasses, “results in a blend to analog and then (of course) back to HD.” Signal disturbance is a challenge in the analog world, too, he notes.

“The real issue is that the blend back to analog results in such a dramatic change in quality and also loss of the stereo image that it is disconcerting. Also, the frequency at which the blending occurs can become extreme in an urban situation and result in further irritants,” he continued.

“As Greater Media’s Chief Engineer Larry Paulausky in Philadelphia has suggested, perhaps some kind of statistical computation in a radio could be used to minimize the blends, based on a recent history of reception.”

Lincoln Financial Media VP of Engineering Barry Thomas agrees with Smith that it’s too early to say if AM HD can be considered a success, or, according to Thomas, what its future holds. Both say they’ve not experienced HD Radio-related interference. Of Lincoln Financial’s five AMs, four are transmitting IBOC signals.

Smith said, “If improvements could be made in the robustness of reception — and I realize that’s a tall order, given both the available bandwidth and the very tough environment of the AM spectrum — its future could only be enhanced.”

Engineering consultant Bert Goldman does not consider AM HD a success so far, pointing out the technical challenges with AM are far greater than with FM.

“I hope AM HD Radio has a future, but I think the solutions to interference are proving to be far more elusive than were first expected,” he said. From his experience in the field, “There are considerable interference issues with AM HD,” and not just at night.

“Even when stations are operating their HD properly, there is noticeable interference to stations on adjacent channels, daytime and nighttime. I have heard this interference on stations which are second and third adjacencies.”

He recently had a situation in which an AM had a problem with its IBOC signal. “Whereas prior to the problem there was some noise on second and third adjacencies, the signal was causing noise all the way out to 50 kHz from the host HD station,” Goldman said. Several stations were experiencing the problem and sought help; Goldman said his company was able to identify the offending station. “They were very cooperative and removed the HD immediately until they were able to correct the problem.

“It’s certainly understandable that stations will have problems with any transmission system,” he added, “and hopefully any that do will act as responsibly as the station I referred to; but it points out a danger where not all situations like this may be quickly identified and corrected.”

AM stations on the air with HD Radio over recent years. Chart prepared for Radio World by BIA/Kelsey. Goldman also is part of the Broadcast Maximization Committee, which supports expanding the FM band down to TV Channels 5 and 6 for digital-only operation. As part of the committee’s proposal, AMs that wanted to do so could migrate to that band, replicate their daytime footprint and add at least one additional stream of audio.

Even if this plan received FCC approval, it would take a number of years to implement. But “for a long-term solution, I think this has more potential than either refining the AM HD problems or waiting for all AM stations to convert to HD-only,” said Goldman.

‘A good tool’

Cris Alexander, director of engineering for Crawford Broadcasting and a contributor to Radio World, said that of the company’s 13 AMs, 11 transmit HD signals. The company has not taken HD Radio off any stations but had to “significantly” modify the digital carrier level of one, KBRT in Los Angeles, in an effort to mitigate interference to an overlapped second-adjacent station.

He said Crawford has been on both sides of the interference issue, receiving interference from another station and reportedly causing interference to another. Both cases were in the L.A. market. He said the company was able to work out compromises amicably with the other stations.

“In the interference-received case, the other station reduced its upper digital carriers by 2 dB and by doing so reduced its 25 kHz third-order intermod products by 6 dB or more, alleviating the interference from the third-adjacent channel station.

“In the interference-caused case, we essentially turned off our upper digital primary carriers.”

HD coverage and performance on that station, KBRT, remain good, Alexander said, “and we believe this demonstrates that asymmetrical sidebands offer a good tool for mitigating interference where it occurs.”

Several observers say economic pressures have worked against AM HD. One engineering group head said AM IBOC is “expensive [and] difficult, and AMs are becoming more problematic. They’re not the profit centers they used to be.”

One source, formerly with a large radio group and familiar with handling a broadcast cap-ex budget, said obtaining financing is difficult in this economy, especially for smaller stations, the kind iBiquity hopes will convert. Additionally, publicly owned groups are being “squeezed by private equity guys.”

“Prices go up if you’ve got a directional antenna because the system has to be designed and tuned to accept the signal with minimal signal degradation,” the person said. “It’s more expensive for AM than for FM … for a broadcast system that doesn’t provide the financial return that an FM will.” If you’re spending more money for a lower return, “financial backers question that,” he said.

Glen Clark, president of Glen Clark and Associates, a boutique engineering firm specializing in high-power AMs, said AM HD faces “the perfect storm” including a lack of confidence in financial markets that has affected the economy. He points to the trend of AMs putting even their big-ticket talk programming on FMs. And now, “Broadcasters are fighting off the fact that bankers hate us and Steve Jobs has the under-25 crowd listening to MP3s.”

Economic bounce?

Some observers predict that stations, AMs included, will resume HD conversions when the economy improves.

Greg Urbiel, director of engineering for Saga Communications, says the unstable economy certainly has given his company pause for both AM and FM digital expansion. Of Saga’s 91 stations, 30 are AMs; of those, six are HD. Saga has had some difficulty with a transition to a folded unipole antenna in Milwaukee; all of the other HD AMs have been providing full service since inception, he said.

“When dollars have been recently available on the transmission side, they’ve been to replace some of our aging FM rigs. And we make the HD transition for that station at that time. There will be more AMs to follow as we do life-cycle replacements,” he said.

Speaking as an individual, Urbiel said he reaps the benefits of CBS Radio-owned WWJ(AM) in Detroit operating in HD. “I am always impressed that I get to listen to ‘studio quality’ at my desk. I personally enjoy and appreciate it.”

Alexander of Crawford Broadcasting said that, whil noting the improvement of digital AM over analog, Crawford is aware that digital AM growth has stagnated.

“Even within our own company we have opted not to convert a couple of stations for economic reasons. It is our belief that the economy is ultimately behind this stagnation and our hope that growth will resume when the economy and business picks up again.”

A new configuration

In response to AM criticisms, iBiquity developed an optional AM IBOC transmission configuration meant for digital AM stations that air talk content, have low audio program density or are not planning to send discrete data.

Some high-powered AMs told the company that certain wideband receivers made before 2003 produced audible interference to a host station’s analog signal from the digital secondary and tertiary sidebands.

The new MA-1 exciter configuration reduces the digital bandwidth and increases the analog bandwidth of the AM IBOC signal, according to the company.

IBiquity tested the new configuration in its lab, then in the field on three stations for a month; it believes the configuration will reduce host interference and give a station uniform digital coverage “out to the point where the digital ends,” according to Jeff Detweiler, director of broadcast business development.

With the new configuration, digital AMs can transmit using the full 10 kHz bandwidth.

Detweiler said a number of AMs are interested in trying out the new configuration.

Sterling Davis, vice president of technical operations for Cox Media Group, confirmed his company is interested in testing the MA-1 configuration when it’s available. Cox turned off four or five AMs in 2007, Davis recalled, because of complaints within the company about self-interference, as Radio World reported at the time.

His personal belief is that digital will keep radio up to date in the future. Davis would like to see a government mandate for radio to go digital, as there was for television.

Harris and Nautel confirmed they are testing the new exciter configuration. Tim Anderson, manager of strategic radio market/product development for Harris Broadcast, said testing of the new “Reduced Bandwidth Mode” is underway in its Mason and Quincy labs.

“This mode can also reduce the cost of implementation as it relaxes the more stringent antenna bandwidth symmetry requirements,” Anderson said. Harris is seeing “significant” interest in the new operating mode and Anderson says “several” broadcasters who had turned off their digital AMs are interested in beta testing it. Harris expects the new mode to be available as an upgrade to its Dexstar AM Exciter this fall.

Nautel is factory testing the modified MA-1 mode AM HD exciter configuration and plans to release it soon, according to Hal Kneller, market development manager, who notes that Nautel’s first broadcast transmitters were AM systems and the company continues to invest heavily in AM. Nautel believes the change could produce a “noticeable change in listeners’ receivers.

IBiquity believes the modified MA-1 mode works and is hoping to get feedback from stations evaluating it. “We’re interested in ‘Does it meet their expectations?’” Detweiler said.

How Many AMs Are HD? The number of AMs transmitting HD Radio is much smaller than the number of FMs doing so, but stating an exact total is problematic. It’s also hard to gauge how many have turned AM HD off.

There are approximately 4,790 licensed U.S. AMs. In August, an FCC database listed 293 with digital licenses, about 6 percent of all AMs, though being licensed does not necessarily mean the digital is currently on the air.

IBiquity in August said 286 AMs were airing digital, and 51 more were licensed but not yet on-air. Earlier this year research firm BIA said 322 were on-air with digital; it said it gets its information from iBiquity; but the latter said BIA also collects information from stations directly and therefore its databases may not match.

What about stations that have turned HD AM off? In total, according to iBiquity, some 52 have been on the air but are now off due to technical problems, mainly antenna broadband issues, or for other reasons. Some stations do inform iBiquity when they have gone off, usually temporarily and for maintenance and/or repair reasons, the company said. For example, in Minneapolis this summer there have been periodic “on/offs” associated with repairs to a tower. “Given the proximity of this to key retailers, we are pretty tuned to this dynamic,” said an iBiquity spokesman. (Best Buy is headquartered in Minneapolis.)

However, as the main article reports, at least some AMs have turned off HD Radio without the intention of turning it back on anytime soon.

Engineering consultant and IBOC critic Barry McLarnon’s list ( showed 245 AMs on-air with IBOC in mid-August, with 48 believed to have turned it off completely. However the list relies on a variety of anecdotal reports sent over time.

So to summarize available numbers: BIA in April said 455 AMs had been licensed, of which 322 were on the air. The FCC in August listed 293 digital AMs licensed. IBiquity in August said 286 AMs were on the air, 52 had turned it off for various reasons and 51 were licensed but had not yet turned it on. IBOC critic Barry McLarnon thinks 245 were on in August and 48 were believed to have turned it off.

— Leslie StimsonReceiver sales

But improved transmission technology will not put more receivers directly into the market. Some observers blame poor receiver availability for the lack of uptake among AM stations.

Jake Robinson, director of engineering and IT for Emmis Communications, says HD Radio in general suffers from poor adoption by consumers and manufacturers. The broadcast group has two AMs; one of those, WFNI in Indianapolis, is airing an HD Radio signal.

AM HD’s future lies in the vehicle and receiver manufacturers’ hands, he believes. “It needs to be standard in all radios. If you purchase a new TV today you will be getting an HD-capable device, period. Radio needs to be the same,” said Robinson.

“If everyone buying a new car or purchasing an AM/FM radio-capable device automatically gets HD, consumer penetration will significantly increase and help give HD the legs it needs to stand on.”

Tom Ray is vice president/corporate director of engineering for Buckley Broadcasting and WOR(AM) in New York, and a Radio World contributor. He says that of Buckley’s seven AMs, only WOR, is digital. “We’re waiting for the [HD] radios to be out there and commonly available,” he said.

Inadequate marketing is holding that up, he believes, and consumer education about HD Radio needs to be ramped up. Tabletop HD Radio receivers need the loop antenna that comes with the unit, he said; many buyers throw it away.

With car radios, the consumer needs to understand the settings on the radio — such as digital-only, analog-only and auto modes. “These are usually explained somewhere in the manual. How many consumers read the full manual?”

A “quick start” guide would be the better place to put this information, and/or a separate flyer explaining HD Radio, how it works and what to expect if you select one of the modes, he said. “Otherwise, the consumer is going to assume that ‘it just doesn’t work’ and ignore the technology.”

AM HD needs to be made easier for consumers so they know what to expect. Ray recently described his dissatisfaction with HD Radio marketing in an article about trying to find a factory-installed in-dash radio for his new Ford (Radio World, Aug. 11).

Additionally, Ray and Laird pointed to the proliferation of electrical noise that plays havoc with the AM band. This too affects AM HD adoption. Ray said it’s time the industry acknowledged that AM reception isn’t what it was even 10 years ago and thinks perhaps it’s time to redefine the service contours for AM.

“In many locations, you cannot listen reliably to AM stations much beyond their 2 milliVolt contour, never mind the half milliVolt,” he said. Laird described as “alarming” the rate at which urban electrical noise is rising. With continuing increases, “it can be argued that AM radio reception will no longer be practical except for those stations with very strong signals.

“When digital reception is possible in an electrically noisy environment, AM IBOC gives a station significant advantage. As the count of auto receivers increases, IBOC AM will have a distinct advantage over analog stations. We believe the advantages of AM IBOC outweigh the disadvantages for continued viability of the AM system.”

And what about the group that speaks for many U.S. commercial broadcasters?

The National Association of Broadcasters remains committed to ensuring AM radio has a competitive digital future, spokesman Dennis Wharton said.

“AM HD Radio is a great solution in many cases and admittedly a challenge in some others due to congestion in the AM band. We’re hoping to see more AM-capable HD Radio products in the future as the marketplace matures and innovative solutions are developed for AM broadcasters.”

Radio World welcomes descriptions of your own experiences with AM HD Radio, particularly if your opinion has not yet been heard on this topic. Write to[email protected].