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Will 'White Space' Devices Cause Problems for Cable Watchers?

Kim Hart

By now, you're probably well aware of the debate over the use of so-called "white spaces," or the empty TV channels tech companies want to use to provide wireless broadband services.

You also probably know all about the broadcasters' point of view. They're worried the white space devices, which are supposed to scan for local stations and avoid transmitting any signals on them, will interfere with their programs and cause static for viewers. That "sensing" technology, broadcasters claim, may not work as well as intended.

But these proposed white space devices might also cause interference for cable subscribers, the National Cable and Telecommunications Association, the cable industry's main lobbying group in Washington, told the Federal Communications Commission in a filing yesterday.

Say you're using a white space device in your home and watching cable programs on the TV in you're living room. At current proposed power levels, the device could cause interference within a TV set -- in both analog and digital sets -- and knock out the cable service for a viewer.

If you're using a set-top box, your TV will be more insulated from this type of interference because it provides added protection for the TV. But most people don't have set-top boxes on every TV in their home. If your TV is hooked up directly to the wall, without using a set-top box, there's more risk for interference, said Bill Check, NCTA senior vice president of science and technology.

The portable device also may not be able to detect every cable channel because they're coming in through a coax cable rather than via an over-the-air signal, like a broadcast channel, Check said.

Mobile white space devices might also cause problems for cable providers trying to pick up a channel from a town 100 miles away, Check said. If a cable system's hub is trying to pick up an over-the-air signal from the next town, a white space device may not detect the station is in use, because it is so far away. But if that device crosses the path of the broadcast signal on its way to the cable provider's hub, it could wipe out the programming for an entire community, he said.

Here are a few of the NCTA's proposed solutions for these problems:

-- Reduce the power of these white space devices so they have less chance of causing interference, and prohibit transmissions on channels that have high probability of interference to TV receivers.

-- Prohibit white space operations on channels 2 through 4 to leave room for set-top boxes, as well as other devices like VCRs, to operate.

-- Restrict the operation of fixed devices to at least 400 feet from residential buildings.

-- Require spectrum coordination before operation of portable devices on channels near those being received at "headends," or the cable operators hub in a community.

By Kim Hart  |  September 11, 2008; 10:00 AM ET  | Category:  Kim Hart
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