Ion Plans 2nd Single-Frequency Network for N.Y.C.
Ion and another broadcaster are planning an additional single-frequency network (SFN) for N.Y.C. and will demonstrate the technology at the upcoming NAB show. Also known as a distributed transmission system (DTS), an SFN uses a series of synchronized lower-power broadcast transmitters to replace or supplement a full-power tower. N.Y. broadcasters have been looking into building such a system since Sept. 11, when they lost their World Trade Center- housed facilities. The Metropolitan TV Alliance (MTVA) is proceeding with a govt.-financed SFN test in N.Y. (CD March 23 p5). Ion is working in parallel with Richland Towers, Rohde & Schwarz and an unnamed 2nd broadcaster to test a smaller system in downtown Manhattan, said Ion Pres.- Engineering David Glenn. “We decided we wanted to do on our own,” Glenn said: “It’s easier. We can move quicker if you don’t do it through committee.”
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The Ion SFN will be smaller and easier to run than the broader MTVA effort, Glenn said. Ion’s project will start with a main transmitter and a single repeater. It should be much easier to synchronize the 2 transmitters than the 4- or 5-site network planned by the MTVA, he said: “If that performs as expected, we're going to continue to grow it down Long Island with a couple more translators.” The Ion test will be open to other area stations if it’s successful, Glenn said: “Most of the stations are very interested in it… It’s going to be opened up to everybody at some point.” Ion plans to ask the FCC for special temporary authority to run the network within weeks.
Ion filed a similar request this month to create an SFN in Las Vegas during the NAB show (CD March 16 p6) and expects to receive approval within days. It hasn’t sought permission for the SFN in Manhattan yet because the field test results on an antenna it plans to use didn’t match the published specification, Glenn said. Furthermore, because it sought only a 30-day experimental license to demonstrate the technology at NAB, the application was short on details. “The New York app is going to require much more specification.”
During NAB, Ion will work with Sinclair and Samsung to demonstrate the synchronized broadcast. Sinclair, which used Samsung’s and Rohde & Schwarz’s A-VSB technology to deliver video to mobile devices at CES (CD Jan 9 p2), will again show off mobile broadcasts. “They'll be carrying our HD TV channel and they'll be carrying the Samsung A-VSB,” said Sinclair Advanced Technology Dir. Mark Aitken: “That will be receivable on handheld, portable and mobile receivers.” Sinclair will also demo Harris’ new system to reach mobile TV receivers, Aitken said.
The Sinclair-Ion A-VSB test in Las Vegas will be the first major demonstration of an SFN meant to reach mobile devices, said consultant Merrill Weiss. “It’s been talked about for a long time,” Weiss said: “When you get to the stage of doing mobile reception, single frequency networks will be needed in a lot of cases, if nothing else than to provide gap fillers for areas that are obstructed from a single transmitter.” Few broadcasters are experimenting with SFNs. The work in N.Y. and a Redding, Pa. station’s construction of an 8-transmitter network is the only SFN activity, he said, partly because the FCC hasn’t set the rules for operating SFNs: “The commission taking action on rules for DTS will give a lot more broadcasters confidence they can build systems and know they'll be able to continue operating.”