WASHINGTON — The Pentagon has come out against the U.S. digital TV standard's vestigial sideband modulation scheme and is pressing the Federal Communications Commission to reopen the debate over use of an alternative approach called coded orthogonal frequency division multiplex (Cofdm).
A Department of Defense video working group said it has concerns about "potential problems" with the 8-VSB approach and wants the FCC to reconsider the Cofdm system that's used in Europe. Specifically, the group said it has concerns "about our national capability to employ digital television broadcast systems to communicate with the public during civil and defense emergencies." The group added there is "growing evidence that digital television receivers using 8 VSB modulation may require large, highly directional outdoor antennas for adequate signal reception."
The antennas would likely be destroyed in a weather or national security crisis, DOD officials said.
By contrast, the group said Cofdm "appears to be a robust modulation system, which would significantly improve the ability to guarantee reception in routine and national emergency" situations.
The VSB modulation scheme has come under attack by a growing group of broadcasters who say consumers may not be able to receive digital TV signals with current receivers. Backers of the digital-TV spec said refinements to receivers will overcome most reception problems.
Nevertheless, observers said national security concerns about the standard are likely to carry added weight at the FCC over whether or not the debate over the U.S. digital broadcast standard should be reopened.
The DOD video working group includes military and intelligence representatives along with video experts at the National Imagery and Mapping Agency.
