Ion Pursues NYC Signal Alternative9/07/2007 08:00:00 PM Eastern
New York broadcasters may have a solution to near-term coverage problems for their digital television signals—and a long-term alternative to the planned Freedom Tower antenna—from ION Media Networks and tower operator Richland Towers, which are successfully testing single-frequency-network transmission technology.
New York City’s digital television (DTV) transmission infrastructure was dealt a crippling blow when the terrorist attacks of Sept. 11, 2001, destroyed the World Trade Center, site of many stations’ transmitters and antennas. Since then, a number of stations have found a home on the Empire State Building, where CBS had already created a DTV transmission site, and Four Times Square. But due to both their lower height and limitations on the power that can be transmitted, neither of these sites can deliver the level of coverage previously afforded by the WTC.
Developers and a consortium of stations, the Manhattan Television Alliance (MTVA), hope to solve New York’s long-term transmission problems by building a large master antenna atop the Freedom Tower at the old WTC site, due for completion in 2012. But they still have to address a short-term problem—that there will be inadequate digital television coverage between Feb. 17, 2009, when analog signals cease, and whenever Freedom’s antenna is operational.
For example, WABC’s digital signal from Four Times Square reaches only about 90% of the audience previously served by high-power DTV signals from World Trade, says Dave Converse, vice president and director of engineering for the ABC Owned Television Stations.
“When you’ve got the largest DMA in which a tenth of percent is a lot of people, any time there is an erosion of ten percent or more [of your potential audience], those are big numbers,” says Converse.
Congress has earmarked $30 million to help New York broadcasters solve the problem, and MTVA is exploring several possibilities that would improve over-the-air reception, including multiplexing low-power, standard-definition signals on vacant channels in the digital spectrum to better serve viewers with digital-to-analog converters and simple rabbit-ear antennas. Another possibility would be using a network of multiple transmitters all broadcasting the same channel, which is known as a single-frequency network (SFN) or distributed transmission.
Able to leap tall buildings
SFNs, which actually use the signal echoes from multiple transmitters to help a receiver lock in on signal, are used widely in Europe and have also been employed stateside in Pennsylvania and Virginia to provide DTV service where topographical barriers, such as mountains, or adjacent channel interference made DTV reception problematic.
SFN technology is also being employed by new mobile TV ventures such as Qualcomm’s MediaFLO, which like an SFN’s ability to provide robust reception on small handsets in interference-prone urban areas.
While an SFN differs markedly from the “one-big-stick” model that the U.S. digital television system is modeled after, it may well solve the coverage problems in New York, particularly within midtown Manhattan, says ION president and CEO Brandon Burgess. To that end, engineers from ION and Richland Tower engineers have already been testing an SFN in New York, using a high-power transmitter in West Orange, N.J., supplemented by four low-power transmitters dispersed throughout midtown Manhattan and surrounding suburbs that simultaneously broadcast on the same channel.
Early tests show the trial SFN provided coverage equal to or better than what Empire State Building frequently delivers, says Burgess, and at a fraction of the cost of signing onto the Freedom Tower’s giant antenna system, which sources indicate could run $20 million or more per station.
“It seems to have checked out quite positively in terms of coverage, even in midtown Manhattan, where Empire has some issues,” says Burgess.
The New York tests aren’t the first time ION has experimented with an SFN. The station group, which is also spearheading broadcasters’ efforts to create a mobile DTV standard through the Open Mobile Video Coalition that Burgess helped found, tested an SFN at the NAB show in Las Vegas to show how it could facilitate mobile TV reception. That test used very low-power transmitters and the same transmission technology from Rohde & Schwarz and Samsung that is being employed in New York.
Burgess says his interest in an SFN for the Big Apple is not just about cost-effectively replicating broadcast coverage, but also about enabling new mobile services through the DTV spectrum.
“We have a dual agenda,” says Burgess. “We like the cost efficiencies of the distributed approach, but second of all, it’s a beta test for mobile TV.”
MTVA is conducting its own tests of distributed transmission model and will be testing the use of multiple low power transmitters in Brooklyn, one of the areas most affected by Empire State Building’s coverage problems.
Paul Bissonette, MTVA president, estimates that that one million New York viewers rely solely on over the over the air TV and two to four million more use it for secondary sets. He says he welcomes suggestions from Ion Richland and anyone else working on a transmission solution for NY.
MTVA Transmission consultant Merrill Weiss says the Samsung technology ION is testing isn’t that different at a high level from SFN technology he has already deployed in Reading, Pa. and State College, Pa.
Weiss adds that SFNs could benefit other crowded urban markets, such as Chicago or Philadelphia, as well as markets with geographical barriers to full coverage such as Los Angeles, San Francisco, Portland and Seattle.
To that end, David Denton, senior VP for Richland Towers, says his company is working to set up SFNs in Los Angeles, Chicago, San Francisco and Denver.
Richland would employ a “one-plus-four” model for its New York SFN, says Denton, with a high-power transmitter in West Orange serving as the hub and four supplemental transmitter located in midtown Manhattan, Brooklyn, Westchester County and Long Island.
ION currently broadcasts analog channel 31 and digital channel 30 off the Empire State Building. Burgess says the capital cost for the SFN would be less than 20% of the cost of buying a stake in the Freedom Tower stick.
Says Burgess, “We’re a small company, and we don’t have as big an installed base. We look at it from the standpoint of the 80/20 rule: If we can get to 80% coverage with a solution that’s a fragment of the cost, that’s the way to go.”
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