Despite that tight schedule, two big unknowns still confront the engineers at WRC-TV and its partners at WHD-TV, an experimental digital-TV station next door: how many viewers in the nation's seventh-largest TV market will be able to receive the broadcast DTV signals, and when.

Stations nationwide are feeling their way as they wait for new equipment, build transmitter towers and complete other last-minute engineering tasks. "It's a real bootstrap operation," Bruce Miller, president and chief operating officer of WHD-TV, said in an interview. "The equipment isn't ready."

The biggest fear among affiliates is that the quality and consistency of digital broadcasts won't be up to par compared with NTSC broadcasts. Smoothing out the wrinkles may take a year or so, Miller predicted.

In the meantime, Miller, a former vice president of engineering at PBS (Alexandria, Va.), had this advice for owners of the first, expensive digital-TV receivers: Buy a good outdoor antenna, for about $100. That will let them receive DTV broadcasts from their local stations.

Indeed, the resurgence of the outdoor TV antenna prompted the Consumer Electronics Manufacturers Association (CEMA; Arlington, Va.) to create an antenna group within its DTV Accessories Division. "Until cable companies pass through a full HDTV signal, antennas may be the only way for consumers" to receive local affiliates' signals, said CEMA president Gary Shapiro. "Today's antenna technology . . . provides remarkable reception if the correct type of antenna is used."

The CEMA antenna group includes most of the top consumer-electronics manufacturers. The group is assisting retailers in determining how to use antenna specifications and a corresponding color-coded map that shows local reception areas in 211 digital TV markets.

A big concern among stations in the top 10 U.S. markets is the multipath "ghost" images that result when signals reflect off large buildings. Motorola Inc. and others are working on filtering techniques to control the ghosting problem.

Elsewhere, concerns about digital-TV reception and interference with adjacent NTSC channels have prompted Washington-based Maximum Service Television (MSTV), a technical group representing local affiliates and station co-sponsors, to conduct field tests with WHD-TV to collect data on adjacent-channel interference caused by digital-TV channels. The tests will "lock together" analog and digital TV transmitters to determine the amount of interference the configuration causes and what can be done to reduce it.

Meanwhile, WHD engineers are helping MSTV member companies complete testing of digital-TV encoders and decoders so that new equipment can be shipped to eager local stations in the nation's 10 largest markets.

Local broadcasters must fill in even more programming gaps before digital TV is considered whole. For instance, closed-captioning services, which would be fed directly into the digital video stream, still aren't ready to go. Miller said the FCC will likely have to issue digital broadcasters a waiver from requirements to provide closed-caption services so that DTV broadcasts can start on schedule.

Also missing at most stations is a system for helping viewers locate new digital TV channels that are often nowhere near the stations' corresponding NTSC channels. The Program System Information Protocols (PSIP) must be made compatible with all new digital TV receivers before PSIP encoding and decoding can be implemented, WHD-TV's Miller said. The model station was the first to air a full-blown PSIP capability.

Despite the lingering concerns, industry observers said most big-market stations are determined to start broadcasts so that set makers will have something to show consumers.

"I don't see the worry and concern that we saw a year ago," said Gary Schultz, principal analyst for the Multimedia Research Group (Sunnyvale, Calif.). Making the transition to digital broadcasting is a business decision, Schultz added. "It's not an undoable task. But it is a big task."

The idea behind WHD-TV was to make the task a little easier. The two-year-old station was formed to help local broadcasters work out kinks in their DTV plants and to showcase new digital broadcasting technology. The test bed also allows equipment makers to debug gear before it goes out to TV stations around the country. For instance, a team of Mitsubishi engineers visited in mid-September to debug the station's DTV encoders and decoders.

The model station's microwave link to PBS headquarters was used to show the feasibility of multiplexed NTSC/DTV operation and to provide access to PBS' satellite uplink.

Primarily, though, the station serves as a test facility for broadcast-equipment makers. The key focus of fielding testing, MSTV said, is indoor and outdoor reception of digital-TV signals. Eight receiver manufacturers participated in field tests of their prototype receivers. Test results were then used to improve receiver designs.

Receiver- and broadcast-equipment makers have staged a number of high-profile high-definition broadcasts over the past year to build excitement for the new technology. In late March, they broadcast an Opening Day game of the 1998 Major League Baseball season from Arlington, Texas.

The next demonstration broadcast before digital programming begins next month will be an HDTV broadcast of the Oct. 29 launch of Shuttle Discovery that will carry Sen. John Glenn, D-Ohio, back into space. The digital broadcast will be carried by WRAL-TV (Raleigh, N.C.), the first experimental HDTV station.

The local PBS affiliate in Washington, WETA-TV, will begin broadcasting HDTV programming on Nov. 9.

Among the networks, CBS is expected to offer the most HDTV programming. NBC initially will transmit mostly upconverted standard-definition signals with some HDTV programming during prime time and on weekends. It also intends to use both interlaced and progressive-scanning formats. The network will make its first big splash in HDTV when it begins broadcasting "The Tonight Show" with Jay Leno early next year.

For now, local stations have their hands full just getting digital broadcasts on the air by Nov. 1. The details will have to be worked out over the next year. Until that happens, WHD's Miller said, "This is going to be largely network-driven."