DTV tests lack clarity

Hill gets an eyeful but still isn't sure which way to go

House lawmakers went to a lot of trouble last week to get a handle on the debate over the DTV transmission standard.

But anyone hoping to get a grip on the issue through dueling demonstrations of rival technologies conducted during a House Telecommunications Subcommittee hearing ended up grasping at the air.

Despite hooking up three big-screen monitors and watching broadcasts of the Washington area's four DTV stations, lawmakers ended the day unable to tell who has the upper hand in the fight between proponents of the current 8-VSB modulation standard, picked by the Advance Television Systems Committee, and the COFDM standard favored by Sinclair Broadcasting and allies including NBC.

"We need some clarity on this point," Subcommittee Chairman Billy Tauzin said after watching the inconclusive demos. "We've got this blame game going on."

In Sinclair's demo, a simple bow-tie antenna placed on the witness table picked up an experimental broadcast of a COFDM-supported signal but couldn't maintain an acceptable picture of 8-VSB stations. But before anybody could put a nail in ATSC's coffin, a set-top antenna placed in a hearing room window by 8-VSB supporters Zenith, NxtWave Communication and the Consumer Electronics Association worked perfectly through repeated channel changes. (As a testament to the risks of live demos, the 8-VSB supporters were slightly embarrassed to stumble across a PBS program on insect reproduction and a Sally Jesse Raphael episode on boot camps for troubled teens.)

Tauzin prodded the 8-VSB camp into reluctantly admitting that their test might have failed if their antenna had been placed on the witness table.

"I'm trying to find out among you dueling engineers who's more credible," he said.

Glaringly absent from the witnesses were the major networks that have taken sides in the debate: NBC and CBS.

NBC did, however, pen a letter to Tauzin citing "real-world" tests indicating 8-VSB's problems with indoor reception. But CBS countered that effort by submitting results of its Philadelphia field test showing that 8-VSB works just fine indoors.

As for the FCC, which is conducting its own tests of 8-VSB receivers, there is no wavering in its support for 8-VSB. Noting that the National Association of Broadcasters and the Association for Maximum Service Television are conducting their own transmission tests, FCC Chief Engineer Dale Hatfield worried that some in the industry are exploring COFDM because of its advantages for mobile services rather than any worries about TV reception. "This raises fundamental issues regarding the intent of Congress and the commission's rules providing broadcasters with a free second channel for DTV operations," he said.

Hatfield also echoed FCC Chairman William Kennard's warning that no transmission changes will be permitted if it causes changes in channel allotments or increases interference.