Audio Video News

At the insistence of renegade broadcasters led by the Sinclair Group, the Federal Communications Commission began reviewing the specifications for over-the-air 8-VSB digital television (DTV) signal transmission back in 1999. Even though tests demonstrated that there may be weaknesses in the standard chosen by the Advanced Television Standards Committee (ATSC), the FCC reaffirmed its commitment to 8-VSB a little over a year ago.

Hoping to build on the 8-VSB DTV standard, Zenith Electronics announced last week at NAB 2001(the annual convention of the National Association of Broadcasters) "E-VSB" technology, a series of compatible enhancements that the company says are aimed at strengthening the overall performance of digital TV broadcasting.

In addition to enhancing terrestrial reception to fixed antennas and receivers, Zenith says that the E-VSB system will be applicable to portable and pedestrian DTV service, and in the more robust modes, even mobile service. The company adds that use of E-VSB would not require modifications to the FCC's emission standard.

On April 2, the company says that it formally submitted its E-VSB plan to the ATSC, which established a subgroup to explore possible VSB Enhancements. According to Zenith, E-VSB is a set of enhancements to 8-VSB that trades "payload bit rate for robustness." Zenith also claims that its multi-rate modulation method is fully compatible with the current ATSC standard and transparent to standard ATSC receivers already deployed.

The company, which had developed the original VSB digital transmission system, says that properly equipped E-VSB receivers will be able to decode both standard 8-VSB and enhanced E-VSB programs and data with substantially improved multipath performance for both, as well as significantly improved "white noise" performance for the enhanced programs and data.

There are currently 186 television stations spanning 64 media markets broadcasting digital programming to an estimated two-thirds of all U.S. TV households. Under the FCC's current timetable, all commercial TV stations must be broadcasting digitally by May 1, 2002.