we’ve heard from some HD Radio proponents that perceived ills of the AM band,
like susceptibility to massive interference, could largely be solved if stations
went all-digital on a wide-scale basis.
After all, the IBOC system always was envisioned as a
transitional one, allowing the industry to operate “all-digitally” someday,
rather than in hybrid mode, should it choose to do so and the FCC allow. But
this question was seen as one for the distant future, given market realities;
and many broadcasters have resisted talk about ever “turning off the analog.”
However, the matter of AM’s health and future is a
current industry debate topic. Against that background, members of the NAB
Radio Technology Committee now want to test iBiquity Digital’s all-digital AM
system to quantify any such improvements. This would entail putting one or more
all-digital AM signals on the air experimentally at existing stations.
The idea, I hear, is one of several being bandied
about in discussions about how to help AMs, particularly medium- and
small-market AMs that lack powerful signals, to remain economically viable.
The committee was formed last year. Television has
such a technical committee, and NAB members felt there should be one for radio.
Barry Thomas, vice president of engineering at Lincoln Financial Media, stepped
away from chairing the NRSC subcommittee on RDS to head this group, as we’ve
of an industry’
The idea of all-digital testing is gaining traction
among committee members. They believe the FCC is more open to the concept than
in the past. Stations would need experimental authority to do all-digital
testing, and the commission has acknowledged that many licensees are in a battle for survival.
Meanwhile some AM owners have been talking openly about economic
challenges as well as rising noise levels and other interference sources.
One member of the committee, a head of engineering for
a radio group, asked to remain anonymous but warned that this idea is in the
very early stages. It’s one of several possible technology or regulatory
solutions the committee is considering as it digests an engineering report
about AM commissioned by NAB. He couldn’t discuss specific options with me
because the work is ongoing, the report is not public and the various options
involve many business and regulatory implications.
“We have to be very considered about what we’re
saying, because we’re talking about the survival of an industry,” he said. The
group is prioritizing “things that can be done first on several fronts.” For
instance, another possible approach is to re-transmit AM programming on more FM
“There’s no one silver bullet” for AM because the laws
of physics do come into play as to what can be done to improve the viability of
the AM signal, he stressed.
But the thought is provocative.
About 14 radio groups are members of the committee,
including Beasley Broadcast Group, Buckley Broadcasting, CBS Radio, Disney/ABC,
Cherry Creek Radio, Clear Channel Radio, Cox Media Group, Cumulus, Delmarva
Broadcasting Co., Emmis Communications, Entercom Communications, Greater Media,
Hubbard Radio, Journal Broadcast Group and Lincoln Financial Media. More groups
are joining, I hear.
A number of NAB member groups, including CBS and Clear
Channel, have indicated they want to participate in all-digital testing.
Beasley is another. Vice President of Engineering and
Chief Technology Officer Mike Cooney tells me the key is to find an
underperforming station and turn off the analog temporarily in order to test
the all-digital system, both day and night. Beasley particularly is interested
in all this, having previously turned off the digital on several of its AMs due
to interference concerns, as we’ve reported.
Years ago, I remember, iBiquity conducted tests of its
AM all-digital technology and anecdotally reported an increase in coverage. But
that was with the HD gear of several generations ago. It would be critical to
see all-digital AM performance with the HD Radio gear of today. IBiquity has
also said for years that interference issues on the band could be improved with
an all-digital system.
Further, with all-digital, “your bandwidth goes from
30 kHz back town to 20 kHz,” said Cooney. An all-digital AM system also
requires less transmission power. Benefits could include enhanced audio fidelity
to the listener and a bigger “data payload” with which AMs could offer some
data-oriented services. Again, engineers need testing results to quantify the
But when a broadcaster goes all-digital, for testing purposes
or for real, it needs to turn off its analog transmission; and analog listeners
are the vast bulk of its audience and revenue. So in discussing testing, the
committee has only begun to dip an industry toe into murky water.
With a smaller receiver base capable of AM digital
reception, the topic of a widespread all-digital conversion raises huge
implications and may involve years of market preparation and coordination among
broadcasters, iBiquity Digital, the National Radio Systems Committee and
transmission and receiver manufacturers — as well as FCC approval. Those are
long-term questions but they suggest why engineers are so leery of talking
about the idea openly.
Test costs, at least, for radio groups that have
already invested in AM HD Radio equipment, would be minimal. If a station is
transmitting a hybrid analog/digital signal, going all-digital just involves a
software change on the transmitter and menu selection on the exciter. However,
if the industry were to move toward “all digital” more broadly, stations that
don’t have HD Radio gear — which is most AMs — would have to choose whether to
invest in it.
Some AMs, particularly those with multi-tower
directional antennas that are too narrowband to pass a digital signal, might
never be able to make AM HD Radio work without huge investments. There might be
another technical solution or solutions plural for those facilities. That’s one
of the reasons the committee is looking at multiple options.
idea of the testing is to get some real-world data over a sustained period of
time and quantify the results. “We would do before-and-after signal
measurements to compare analog and digital coverage differences,” Cooney tells
me. Testing also would determine whether an all-digital signal caused any
first-adjacent interference, or improved existing interference. Drive tests
would be conducted in rural and city areas in several markets. The other
engineer with whom I spoke says the committee hopes several stations in one market
would take part in the tests.
any talk of an all-digital AM future, either for individual stations or the
industry at large, is likely to be contentious given the money to be lost if a
station — or an industry — chases away analog listeners. Where to test, which
stations to test on and how long to test are questions to be determined; but that
conversation would only foreshadow a huge industry debate should the idea go
“You can’t look at current ROI,” said my unnamed
committee engineer. “We need to look at it as ‘If I don’t do this now,’ meaning
turn off the analog for long-term gain, ‘how much will I lose three years from
After I reported about this topic online, I received several comments
from engineers asking whether AM HD would be compared by the researchers to the
Digital Radio Mondiale system as well. I have the sense that may not happen
initially given the lack of DRM consumer-grade receivers in the United States.
(You start to wonder if there’s a bigger “digital platform” debate yet to come
I hope the NAB will release the details of its
engineering report soon. These conversations need to happen in the industry at
large. But the idea of testing the all-digital system is intriguing. While
big-market AM powerhouses may remain profitable, the economic picture is not so
rosy for many AMs, some of which have turned to rebroadcasting their signals on
“The radio groups want their AMs to remain viable.
Some 40 percent of the industry is still AM on a station count basis,”
estimated the first committee engineer. “We want to identify ways that stations
can remain viable or become viable again.”
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