TV BROADCASTS warning of approaching hurricanes or tornadoes, or other civil
emergencies, might not reach American homes when digital TV becomes the norm,
according to video experts at the Pentagon. This claim puts one US government
agency at loggerheads with another in the acrimonious debate over standards for
digital TV.
Stephen Long, chairman of the Department of Defense Video Working Group, has
called on the Federal Communications Commission to conduct a public debate
questioning the 鈥渃ontinued use鈥� of the digital TV standard set by the FCC in
1997. Long believes the standard, called 8VSB, could prevent emergency
communication with large sections of the public. 鈥淭here is growing evidence that
digital TV receivers using 8VSB may require large, highly directional outdoor
antennas for adequate signal reception,鈥� Long says. Such antennas, he points
out, may be the first things destroyed in storms or other disasters.
But Robert Graves, who heads the FCC committee that set the standard, claims
that Long is basing his assertions on 鈥渟cientifically unsound鈥� test data from a
group of commercial TV stations who want the FCC to let them use a rival
standard called COFDM鈥攚hich delivers digital TV in Europe
(New 杏吧原创, 30 October, p 23).
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The rebel broadcasters鈥攍ed by the Sinclair Broadcast Group of
Baltimore, Maryland鈥攕ay their tests show 8VSB only works well with TVs
using large outdoor antennas. They say that indoor set-top antennas and portable
TVs have trouble coping with signal echoes from buildings and vehicles, which
blank out the picture. But the COFDM standard uses echoes to reinforce the
picture signal, so set-top and portable antennas still work.
Graves dismisses the rebels鈥� criticisms. He claims that Sinclair鈥檚 engineers
did their tests in unusually difficult locations using the 鈥渨orst 8VSB receivers
on the market鈥�. Newer 8VSB receiver technology shows 鈥渄ramatic improvements鈥�,
Graves says.
The Pentagon, however, believes that COFDM could improve reception of both
standard and emergency broadcasts. Nat Ostroff, Sinclair鈥檚 technology chief,
says: 鈥淭he entry of the Department of Defense on the side of COFDM is very
helpful in raising the legitimacy of our position. They represent a truly
independent evaluator.鈥�
But the two sides will eventually have to agree the best way to handle
emergency broadcasts in the digital age. The National Hurricane Center in Miami
says TV remains the best warning medium. Its spokesman Frank Lepore says:
鈥淪eeing the satellite pictures of the storm approaching makes believers of
辫别辞辫濒别.鈥�