ABC, NBC Raise DTV Standard Concerns

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Washington-ABC Inc. and NBC have joined the chorus of broadcasters raising troubling concerns about the only over-the-air digital-transmission standard authorized by the Federal Communications Commission.

In recent FCC comments, the networks said they were alarmed by the deficiencies in the standard, known as 8-VSB (vestigial sideband), which were revealed by research conducted in the field and in the laboratory.

They urged the FCC not to embrace the standard as final until further testing of 8-VSB and competing versions had been conducted and evaluated, which, they added, will take at least the remainder of the year.

ABC and NBC told the FCC June 16 that testing of a new standard, known as COFDM (code orthogonal frequency-division multiplexing), was needed because their own research and research in Brazil found that next-generation digital-TV receivers would not overcome the problems with the FCC-approved standard.

"We ask the FCC not to foreclose the possibility of modifying or supplementing the standard to allow COFDM as an option if the test results support such a conclusion," the networks said.

The most practical problem was that the FCC standard degrades indoor picture quality when off-air signals bounce off buildings and arrive at indoor antennas at different times. As a result, a digital-TV viewer must adjust the antenna each time he or she wants to change the channel.

The second problem ABC and NBC highlighted was that 8-VSB is unsuitable for TV stations that want to beam wireless services to portable and mobile devices-a booming market broadcasters want to invade.

The effort to reconsider 8-VSB is spreading. On June 28, the Advanced Television Systems Committee-which developed 8-VSB-said a previously formed task force would look at whether 8-VSB can be modified to accommodate mobile services.

But ATSC executive director Mark Richer said there were no guarantees that any modification to 8-VSB would be backward-compatible-meaning whether it would work with digital-TV sets consumers have already purchased.

Sinclair Broadcast Group was the first TV-station group to complain about problems with 8-VSB and to champion COFDM, the standard used in Europe. Leading a group of 300 stations, Sinclair urged the FCC to allow stations to use COFDM, but the agency refused in February, saying that 8-VSB was robust enough to meet consumers' needs.

The fuss over the digital-TV standard has complicated the issue at the FCC over cable carriage of both analog- and digital-TV signals during the transition, which is set to expire in 2006 if 85 percent or more households in a market can receive digital-TV signals either through digital-TV sets or digital set-top boxes.

The National Association of Broadcasters had repeatedly demanded that the FCC require cable systems to carry both signals.

The cable industry has objected, saying that broadcasters need to clear up their own problems with the transmission standard before the FCC should even consider a double dose of must-carry. That aside, the cable industry is opposed to dual must-carry under any circumstances.

In their comments, ABC and NBC did not mention the ongoing digital-analog must-carry dispute. Instead, they said, their questions about 8-VSB were designed to counter arguments made by the Consumer Electronics Association that the digital transition in on course and that the bugs in 8-VSB will be worked out, given enough time.

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