June 30, 2008

Cooperate and Coordinate for the Great Analog Turn-Off

By Monta Monaco Hernon

As with most things in life, the devil is in the details for the broadcast digital TV transition. Without communication and cooperation between operators and broadcasters, cable subscribers could have TV sets that do go dark.

"Feb. 17 will be a scotch and Maalox night. I recommend a 25-year-old McCallum," said David Donovan, president, Association for Maximum Service Television. "On the other hand, if you don't do this right, we will all be drinking Maalox."

Speaking last week during an Expo workshop, "Preparing for the Broadcast Analog Television Turn-off," Donovan explained that many stations currently occupy an analog channel and a temporary digital channel. Operators need to confirm with broadcasters where a station will settle after the transition.

Nearly 1,200 stations will make the temporary digital one permanent and turn off the analog. Alternatively, slightly more than 500 stations will use the formerly analog channel for their digital service. And 117 will be assigned a completely new channel after the transition. Further complicating the issue, some stations will even begin broadcasting their digital on a channel formerly assigned to another station. Confused?

"(We) have to have technical discussions, and they have to begin now," Donovan said. Because of a glitch in timing regarding construction issues during the winter, some broadcasters also will be given extra time to do their tower work. Others might want to do testing.

"You have to know our plans. You have to know whether we are turning off analog early. On the reverse side, we must know where the headends and receive sites are," he added.

Infamous postage stamp

Donovan's co-presenter, Matthew Goldman, vice president of technology, Tandberg Television, spoke of Feb. 17 saying, "This day is going to be in infamy."

Operators must be able to take an ATSC-DTV signal and create a replacement analog signal. The device in the headend must be able to handle, among other things, HD to SD conversion. Coordination between broadcasters and operators again is needed to ensure the proper picture aspect ratio to use during this conversion, Goldman said.

An Active Format Description (AFD) can be used to communicate the aspect ratio and whether center-cut extraction or a letterbox is appropriate. Without proper coding and interpretation by the headend, mistakes could occur causing "the dreaded postage stamp," Goldman said.

"(Sending the wrong code) is like telling someone to turn left vs. right," he said.

Some networks might advise only to use center cut to avoid confusion, but this restricts the network and also could cut off interesting portions happening "in the wings" of an HD-broadcast event. "Always (using) center cut could be ruining the experience of the consumer," Goldman said.

- Monta Monaco Hernon

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