Broadcast Engineering 2002
The theme of NAB2002's Broadcast Engineering Conference was two-fold, looking both to the immediate past while keeping an eye on the industry's enhanced DTV future. In a sober reflection on the events of 9/11, the opening session paid tribute to the television engineers lost in the World Trade Center (WTC) attacks and the remarkable engineering feat their broadcasting facilities represented. Building the 352-foot, 353-ton WTC master antenna was a marvel in its own right, involving as it did hoisting 17 tower sections, some weighing over 27 tons, up the side of the WTC's 110-story North Tower and erecting them on the roof. Dr. Oded Bendov, one of the complex's original designers, and Patrick Walsh, project manager for the installation, shared photos and reflections on an undertaking that consumed much of their lives almost 30 years ago.
The WTC was home to 18 broadcast stations: four radio, nine NTSC TV and five DTV. The DTV stations had come on-line only a few months before. Impressive as it was, and fondly remembered as it is, the complex and its destruction are only minor footnotes in the 9/11 tragedy. Infinitely more important are the human casualties. For broadcast engineers, the loss of Rod Coppola, Donald DiFranco, Steve Jacobson, Bob Pattison, Isaias Rivera, and William Steckman hit particularly close to home. The Society of Broadcast Engineers' WTC Disaster Relief Fund has thus far been able to distribute approximately $41,000 to each of their families, but more is needed and the association is still actively soliciting donations.
While the recent past is compelling, the future knocks incessantly. William Baker, head of the New York/New Jersey Broadcasters Coalition, concluded the opening session by detailing the search for a new home for a combined antenna with as much coverage as was had on the WTC. Governor's Island, Jersey City, Brooklyn, and downtown Manhattan offer possibilities, but a 2000-foot, $200 million dollar replacement faces many hurdles. There are New Yorkers who wouldn't be surprised if the temporary Empire State Building site becomes permanent.
However New York and New Jersey do it, they'll face the same DTV challenges as the rest of us, and the conference devoted most of its time to a few of the more pressing ones. It's no surprise the DTV reception and 8-VSB enhancement sessions drew good crowds. Advanced Television Systems Committee (ATSC) President Mark Richer reported that testing of 8-VSB enhancements was on-track and recommendations were expected shortly. "One of the things about digital," he said, "is it's organic. We change it, we grow it over time."
Some of that change was in evidence with "Casper," a new receiver chip design with longer, roughly equal pre- and post-equalizers developed by Linx Electronics. Richard Citta, one of the originators of VSB at Zenith and now chief scientist at Linx, said development of the chip focused on indoor environments with multiple 0dB ghosts and no dominant signal. The chip tries to use ghosts rather than cancel them. Noting that NTSC signals allot roughly 30 percent for synchronization and COFDM about 12 percent, Citta stated that, "With only 1.5 percent of the ATSC payload devoted to synchronization, we've got to use everything we canÑpilot, band edges, segment sync, field sync, trellis coding...a whole ensemble of time-varying signals."
Initial tests on Casper at the Canadian Research Centre looked promising, and Linx is not alone. Other chip manufacturers are innovating, too. NxtWave demonstrated a dual 8-VSB/QAM chip that could enable cost-effective "cable-compatible" digital sets. It also showed a prototype of a smart antenna array that gets its phase steering instructions from the receiver via the new EIA/CEA-909 active antenna interface. Another part of the reception puzzle is getting signals there in the first place.
Kent Parsons, a University of Utah field engineer, reported on DTV Utah's successful tests of low-cost translators in rural areas. Experiments included passing three 8-VSB signals (channel 3, channel 4, and channel 5) through the 70 MHz port on microwave links and running two adjacent 8-VSB channels (16 and 18) through one low power transmitter. Low power on-channel repeaters similar to MMDS beam benders were also used. Output may not quite meet the FCC mask, but it looks as though (given appropriate waivers) economical rural DTV service is possible.
For other propagationally-challenged licensees, the on-channel, distributed transmission approach suggested by Merrill Weiss, senior partner at the Merrill Weiss Group, a consulting firm specializing in technology, is also moving through ATSC with the expectation of early recommendations to the FCC. Weiss proposed multiple medium power transmitters licensed together as a unit to provide primary service to an area. The result is improved coverage while meeting the same ERP and interference criteria as the single high power transmitter originally contemplated by the FCC. Axcera demonstrated a distributed system on the floor including the input timing hardware needed to minimize overlapping signal interference.
Other sessions at the conference covered TV facility design, antenna and tower regulation, asset management, station automation, and centralcasting. Asset management, automated monitoring, and video-over-IP were at the heart of the centralcasting scenarios. Success seems to depend on whether the savings from centralization outweigh the costs of interconnection, backup, and continued local programming.
A couple of asset management enablers that have been in the works for a while made it to product this year. Among others, Avid, EMC, Panasonic, Quantel, SeaChange International, SGI, and Sony were demonstrating interchange of AAF and MXF standardized files. Sony also had a demo showing how SMPTE Universal Material Identifiers (UMIDs), automatically generated at the camera, help simplify and speed up editing and post production.
In a session devoted to tower regulation and siting, Fred Baumgartner of the National Antenna Consortium and Barry Umansky from Thompson Hine, LLP in Washington DC spoke of their quest for a binding national antenna policy. They sounded hopeful, but you couldn't help feeling that you shouldn't hold your breath.
PSIP is still an issue. The Program and Systems Information Protocol session included presentations from Thales Broadcast & Multimedia, Triveni Digital, and Sharp Laboratories on real-world PSIP implementation, PSIP cable carriage, and PSIP in receivers. Though it's defined in detail in ATSC A/65A, PSIP is complex and broadcasters must implement it consistently both to avoid confusing viewers and to derive maximum branding and promotional benefit. Since PSIP provides the pointers for captioning and other accessibility services, Jim Carruthers of Norpak Corporation and Gerry Field from the CPB/WGBH National Center for Accessible Media used the session to explore creation, carriage, and implementation deadlines for EIA-708B digital captions. NAB's DTV Store had a Zenith receiver with a fully-implemented 708B caption decoder, and on the floor, Sony and Panasonic were showing 708 data recorded on HD videotape using the SMPTE 334/292 standards.
Finally, ATSC data transmission provided a set of bookends for the conference. A pre-conference IEEE tutorial tackled the intricacies of video streaming in general and streaming ATSC data to PCs in particular. It didn't focus on standard DTV encoding but rather on IP transport of MPEG-4, Real, QuickTime, and other streaming formats alongside normal programs in the ATSC stream. Likely applications (some possibly revenue-generating) included corporate communications, training, information kiosks, news, and weatherÑanything that has a large, regional, PC-equipped audience. In addition to exploring various metadata standards and transport schemes, the closing session also looked at non-program-related data as a revenue source. With ATSC data receivers now going for under $150, antenna technology steadily improving, and successful field trials under his belt, Pete LudZ, iBlast's Network Operations executive vice president, felt confident that 8-VSB can deliver special interest video to set-top boxes and download software, games, and business information to PCs while simultaneously broadcasting SDTV and HDTV.
If, after all this, you think DTV sounds like a lot of hard work, you might consider another comment of Mark Richer's from one of the early sessions: "No matter how hard you think digital is, there's no future in analog."
Audio tapes or CDs of the sessions are available from Mobiletape (www.mobil tape.com
) and a Proceedings book with most of the presentations is available from the NAB Store (www.nab.org/nabstore/