Amid broadcast-industry infighting over government
standards for digital television, the technology camp is rolling out solutions to blunt
the arguments.
Semiconductor giant Motorola Inc. and chip developer
NxtWave Communications Inc. last week introduced second-generation digital-TV technology
that they said eliminates the in-home-antenna reception problems that crop up with the
eight-level vestigial-sideband (8VSB) modulation scheme the government has chosen for U.S.
digital-video and data broadcasting.
The latest solution -- and others from the likes of Philips
Consumer Electronics Co. and Microtune Inc. -- addresses an issue that threatens to slow
expansion of the fledgling terrestrial-digital-TV broadcasting footprint, and that also
has ramifications for cable.
"We're committed as an industry that everybody
should be able to access DTV broadcasts," Consumer Electronics Manufacturers
Association director of technology Michael Petricone said. "This is a very good and
important step in that direction. We've said all along that reception was going to
improve -- now you're seeing it."
Barbs have been flying for months over Sinclair Broadcast
Group's contention that the government should consider switching its mandated
transmission scheme from the 8VSB standard adopted by the Advanced Television Systems
Committee to the code-orthogonal frequency-division multiplexing modulation technique used
for digital TV in Europe and Japan.
Sinclair has argued that its highly publicized tests in
March in Philadelphia and earlier this summer in Baltimore showed that COFDM was superior
for indoor digital-TV reception.
But mainstream broadcasting and consumer-electronics trade
groups have challenged those assertions as inaccurate, contending that changing the U.S.
standards would stall the already-slow rollout of digital-terrestrial service in its
tracks.
The arguments indirectly hit cable. Many in the industry
have expressed concern that if consumers can't get good indoor digital-TV reception
using simple, "rabbit-ears" antennas, the government might force MSOs to become
the digital carrier of last resort.
"We're modulation-neutral," said James
Stansberry, marketing director for digital-TV products at Motorola. "But from our
perspective, we see a lot of momentum in DTV. We want to see VSB go because that market is
going, and we don't want to see it stop."
Motorola's solution is its "MCT2100"
demodulator chip, developed with Sarnoff Corp., which has a new signal-processing
architecture that addresses the multipath-reflection problem at the core of
Sinclair's arguments against 8VSB.
NxtWave Communications -- the former Sarnoff Digital
Communications business, which was spun off about five years ago -- separately announced
its own "NXT2000," a multimode VSB/quadrature-amplitude-modulation receiver chip
that the company said could deliver reliable digital-broadcast signals to digital TVs,
digital set-tops and PCs in harsh multipath conditions.
In multipath environments, multiple signals arrive at a
TV-set antenna at different times because of reflections off buildings, cars and other
obstacles -- a phenomenon that can cause ghosting in analog signals and, sometimes, the
loss of digital-TV signals.
The problem has been painted as especially acute for 8VSB
transmissions in high-rise urban landscapes and for in-home-antenna reception.
Stansberry said the Motorola-Sarnoff development -- which
predates the current debate over modulation schemes -- created a unique equalizer
architecture dealing with both short-range and long-range signal reflections.
To do so, the companies had to use advanced semiconductor
processing that Stansberry said resulted in complementary metal-oxide semiconductor
circuit dimensions of 0.18 microns, compared with contemporary CMOS designs of some 0.3
microns.
"We took all of the Sinclair tests -- especially the
worst-case ones -- then went way beyond what they did, to some pretty absurd channel
conditions," Stansberry said. "We basically were validated: Our receivers locked
on and worked in those conditions where they had failed."
Sinclair vice president of new technology Nat Ostroff said
Sarnoff and others accepted an invitation to test their solutions in Baltimore next month.
But he noted that consumer-electronics manufacturers had not yet adopted those solutions,
and he remained skeptical that 8VSB was the best platform for digital TV.
"Our feeling is even if 8VSB works today to the extent
the claims are that it might, we would still want to see COFDM as alternate modulation
standard for broadcasters," Ostroff said. "It offers large degrees of
flexibility regarding data rates and robustness that 8VSB does not."
Stansberry said Motorola began shipping samples of the
MCT2100 late last week, and initial manufacturer responses to its announcement were good.
"Some consumer OEMs [original-equipment manufacturers] are talking about retrofitting
their television sets" with the chip, he added, although he would not identify
specific manufacturers.
Gerry Kaufhold, a principal analyst for Cahners In-Stat
Group, a sister company to Multichannel News, said the Motorola and NxtWave
solutions reflected how digital TV was evolving as a technology just as the
color-broadcasting platform did from its often-balky early days.
"Over the next year, we'll see the second
generation of 8VSB demodulators and error-correction chips that will be better at pulling
signals out of a noisy environment," Kaufhold said. "By 2001, the ATSC
terrestrial-digital system will look great."
Other manufacturers have also been weighing in on the
reception issue.
Thomson Consumer Electronics produced about 25 hours of
HDTV programming from the RCA Championships tennis tournament in Indianapolis the weekend
of Aug. 21 and 22, touting 8VSB.
One demo showed the programming in a 30-story apartment
building in downtown Indianapolis using a Thomson-RCA digital set-top, a 25-inch
television and a "bowtie" set-top antenna.
The company said analog broadcasts viewed from the same
location, using the same equipment, experienced ghosts and picture artifacts, while the
digital version was flawless.
