Workshop Detangles IBOC DAB
IBiquity Officials, Manufacturers Will Take Part In a Day-Long
Seminar on the Status of Digital
Alan R. Peterson
As broadcasters prepare for the IBOC age, a
lot of questions are being asked. Can we use our existing equipment?
How much of the physical plant has to be converted for the digital
process? How soon do we have to be ready?
Will this be the end of analog radio?
By NAB2002 next spring, several IBOC broadcast
products may be available. The first consumer receivers are anticipated
at the 2003 Consumer Electronics Show.
Will the technology really be ready to roll
out on time? What kind of costs will stations incur due to the
conversion?
These questions will be addressed in the all-day
Digital Radio Certification Workshop, Thursday, Sept. 6 from 10:30
a.m. to 5 p.m. at the Morial Convention Center.
Speakers will deal in specifics.
"We did a presentation at NAB2001 in Las
Vegas," said Jeff Detweiler, broadcast technology manager
for iBiquity Digital Corp, the company developing in-band, on-channel
digital audio broadcasting technology.
"This time, we want to explain the technical
implementation, high- and low-level combining and the costs that
are involved."
IBiquity executives and manufacturers tooling
up for IBOC will constitute the panel of experts. Hosting will
be John Marino, vice president of science and technology at the
NAB, and Scott Stull, director of broadcast business development
at iBiquity.
Science project
"Broadcasters have looked at IBOC as a
‘science project’ in the past," said Stull. "We
are hoping to generate a lot of discussion. The session will be
split between the business issues of IBOC, with a nuts-and-bolts
discussion in the afternoon to help stations get ready."
One thought weighing on some broadcasters’
minds is the "demise" of analog radio. Stull said not
to worry.
"There are 600 to 700 million receivers
in use now," he said, "especially those fifteen-dollar
bed-stand AM/FM alarm clocks. We are not recommending any mandatory
IBOC switchover, and a transition could take 12 to 15 years. Broadcasters
and consumers can change over when they want."
Many stations are built out as digital facilities,
with entire audio chains now passing digital bits in place of
analog audio. The only time there is a conversion to analog is
at the transmitter.
"Eventually, we’d like to see an all-digital
path," said Stull. "Lots of people have already spent
millions to go digital in-plant."
Testing out
The iBiquity AM and FM IBOC systems continue
to be tested, with results soon to be submitted to the National
Radio Systems Committee for approval.
One important aspect of IBOC planning is the
studio-transmitter link. This aspect will be addressed by Bill
Gould, broadcast products manager for Harris Corp., among the
manufacturers taking part in a roundtable discussion in the afternoon.
"For one thing, the sample rates have to
be at top levels," said Gould. "Current digital STLs
sample at 32 kHz to provide the 15 kHz audio response of conventional
FM. IBOC STLs will have to have 44.1 kHz throughput."
When stations operate in the hybrid mode of
IBOC, both analog and digital signals must be combined somewhere
along the line. The impact of the digital signal on the existing
analog signal is of concern to broadcasters – a concern not
lost on Gould.
"There are reasons why this may or may
not work," he said. "Broadcasters must maintain the
fidelity they have today and a lot of this is not decided yet."
Answering concerns about transmitters will be
Daryl Buechting, senior manager of radio products for Harris.
Can-do
"A typical question from broadcasters is,
‘Can I do IBOC with my transmitter?’ It can be possible
with an existing FM transmitter, an IBOC transmitter and a high-level
combiner," Buechting said. "A future transmitter will
perform low-level combining, or what’s called common amplification."
Combining those signals and maintaining isolation
between competing IBOC stations also comes under the province
of Tom Silliman, president of Electronics Research Inc.
Eric Wandel, director of product development
for ERI, said, "Tom will be making the presentation at the
NAB Radio Show. Say you have a multiplexed site: four stations,
all combined in one antenna. You have existing transmitters and
IBOC transmitters, and all must have their piece of the spectrum
protected. You need a combination of filters and combiners to
keep them isolated."
Wandel said Silliman will address the needs
of cost, space and cooling requirements for a combiner-filter
system when planning for the IBOC rollout.
Also representing the manufacturing side will
be Jeff Keith, engineering project manager for Omnia/Telos Systems.
Other iBiquity officials on the panel include Senior Vice President
Jeff Jury to provide an overview of IBOC as a business; Pat Walsh,
vice president of wireless data business development, to explain
the revenue opportunities of IBOC above and beyond the audio channels;
and Glynn Walden, vice president of broadcast engineering, to
explain the testing process and what will be handed over to the
NRSC.
The IBOC session is in the same room and immediately
following the session "Engineering Legends," a panel
of recent winners of the NAB Radio Engineering Award.
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