An eight-transmitter distributed transmission system (DTS) operated by Reading, Pa. station WTVE is a prime example of how multiple transmitters can be used to cover a wide area. In this case, WTVE covers an area ranging from Reading through the Delaware Valley and on into Philadelphia. According to Axcera—and as far as I know—this is the largest ATSC DTS in the world.
WTVE and Axcera announced last week that this large DTS is now transmitting the final A/153 mobile DTV standard, making it the first DTS mobile DTV system to use that standard.
"Axcera is the first and only transmitter company to deploy commercial ATSC distributed transmission systems, and is one of just a few manufacturers offering a complete ATSC M/H solution," said David Neff, president of Axcera. "Since ubiquitous coverage is critical for a successful mobile DTV service, we felt that we could leverage our position as innovators of both ATSC M/H and DTS, along with the capabilities of our valued partners, to promote the use of these ATSC-compliant technologies and demonstrate the great opportunity they offer to broadcasters."
The system includes equipment from Expway, Harmonic, Kenwood and LG.
Todd Stewart, general manager of WTVE-TV, commented that Mobile DTV presented extra challenges, as the receiving devices are typically in motion and very close to the ground.
"Mobile DTV requires a much more dense signal than broadcasting to home receivers," Stewart said. "ATSC M/H offers excellent performance in the mobile environment, and combining this with DTS technology will allow us to ensure the best coverage possible to our viewers."
Readers should note that a Rohde and Schwarz distributed transmission system was operational in New York City earlier this year, using two transmitters carrying the DTV signal from WNJU (licensed to Linden, N.J.), as well as a mobile DTV simulcast of WNJU's programming. The system was installed before the ATSC finalized A/153 and was shut down shortly before the standard was finalized when the station moved its DTV transmission facility to the Empire State Building.
A three-transmitter system (Black Mountain, Stratosphere and LVCC) using the same technology was demonstrated during the NAB Show in Las Vegas last April. The Axcera system, however, is the first, as far as I know, to include this many transmitters covering such a large area. And it appears to be the first to use the recently adopted ATSC A/153 standard. Axcera is one of the few companies selling an echo-canceling digital on-channel repeater (ECDOCR) for ATSC. Both DTS and ECDOCRs are likely to be needed to provide seamless mobile DTV coverage along commuter routes and in urban areas.
Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.
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