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NBC moves to digital

NBC is converting the analog infrastructure for its affiliate distribution system to multiple digital encoding systems. The migration from the current distribution system, which broadcasts to about 180 of the network's 217 affiliates via satellite, will enable NBC to capitalize on the benefits of digital transmission and serve as another step toward complete digital-television operation. It also will allow for more capacity to send multiple channels and other ancillary data.

"Digital gives us a number of advantages," said Larry Thaler, director of distribution projects at NBC. "A primary advantage is that NBC will know that the signal we are broadcasting will be received by the affiliates with consistent image and sound quality. Digital is also the key to improving our transponder efficiency and will provide additional audio channels."

In all, five redundant multichannel systems will be installed at NBC's New York and Burbank, Calif., facilities. They will consist of encoders, multiplexers, 8PSK-compliant modulators, and three Director network-management and receiver-control systems—all from Norway-based equipment maker Tandberg Television. The Director systems provide the means to transmit contribution material over satellite while ensuring against unauthorized access to the network's broadcast material. NBC is also replacing the control infrastructure and modernizing uplink-monitoring facilities.

In addition, 975 Tandberg Alteia Plus receivers will be supplied to affiliates across the country. As part of the project, each affiliate will install two racks of gear. According to Thaler, a distribution rack outfitted to receive network programming will be installed at each affiliate this year. The rack will include new receivers, digital switching and new scheduling equipment. A second and third phase of the project, to be completed "in the next few years," will improve the backhaul and transmission infrastructure.

In addition, a series of renovations is being made at the two main operation centers to accommodate the new digital gear. "There are several modifications to the uplink dishes at what we call the Master Sites," Thaler said. "These include new high-powered amplifiers, upconverters, and new uplink-monitoring equipment. In New York, we're also constructing a new equipment room to house the gear."

"We think there will be significant improvements in the quality and reliability of our signal distribution," Thaler said, adding that affiliates will also have improved access to NBC's distribution schedule.

Also, he pointed out, the upgrade is a "critical step" toward terrestrial DTV operation.