When the Federal Communications Commission mandated a nationwide transition from analog to digital television broadcasts, an important question in the transition process was left unanswered: How do TV stations pipe digital broadcasts into rural areas?
In analog broadcasting days now waning, primary VHF signals (channels 2-13) were picked up by repeater stations, amplified and re-broadcast on a separate UHF frequency (channels 14 and up) that kept the waning primary signal and amplified repeater signal from bumping into each other out of sync.
Utah's rural areas are being served by 622 such analog television translators. They will continue beaming signals until at least 2006. The problem is broadcasters are required to begin digital broadcasts no later than 2002, and there aren't enough frequencies to create a duplicate repeater network for digital TV signals.
"There just isn't enough spectrum in all of the UHF allocation to do it," said Greg James, chairman of DTV Utah and vice president of engineering at Bonneville Communications.
So broadcasting consortium DTV Utah is launching an experiment to see if repeaters can cleanly pass digital TV signals through a network of repeaters "on-channel" — without changing the frequency of the signal.
As obvious as the transition problem is in expansive areas like Utah, there have been no field tests to determine whether DTV Utah's on-channel repeater idea will work. "There is some science that tells us we may be able to do this. By September, we hope to know," James said.
James, attending the National Association of Broadcaster's annual convention in Las Vegas this week, is surrounded by discussion of emerging technologies of DTV; and there is global interest in the DTV Utah experiment.
Seven different equipment manufacturers as the Advanced Television Technology Center in New York City are joining forces to build the experimental network. "Companies are donating equipment and money. Channels 5 and 4 are donating our digital capacity on Farnsworth Peak," where the consortium of Utah broadcasters joined forces to add a digital antenna to the existing analog broadcasting towers.
"Historically, on-channel repeaters have proven successful in overcoming communication barriers in other digital services including over-the-air cable and microwave links," said DTV Utah co-chairman Phil Titus.
"We hope and believe our study will be successful in finding that digital signals won't be subject to the same artifacts (picture interferences) seen in analog transmission."
"Digital television should be made available to all citizens, regardless of where they live," said Titus. "We are hopeful that this study will help DTV Utah and broadcasters everywhere make that goal a reality in the near future."