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White Space: Cable Warns of Three Miles of Interference

White space devices—even fixed, licensed ones—could cause interference for cable viewers, the National Cable and Telecommunications Association told the FCC this week. One white space proposal—installing fixed antennas with effective transmit power of more than 3 kW (+65 dBm) in rural communities—could affect cable-ready television sets as far as three miles away, the NCTA claims.

That's in addition to entire communities losing channels because of interference at hubs or headends.

NCTA has previously argued that white space devices could cause interference at the home level as well as at hubs and headends. NCTA said that over the past year, not a single proposal by potential white space users has addressed their industry's concerns.

"We continue to support efforts to open up additional spectrum for the delivery of new wireless communications but it is important that the Commission not lose sight of the over 67 million cable viewers who can also be affected by the outcome of this proceeding," NCTA said.

The industry proposed a ban on white space devices in the VHF channels, or at least on Channels 2-4 used in home cable setups, and a power cap of 10 mW on portable devices. The group also wants to keep all fixed devices at least 400 feet from the external walls of residential buildings.

It wants spectrum coordination before operation of portable devices on channels adjacent to those being received at headends.

The group said auto-location in both fixed and portable devices, combined with a geolocation database of available channels, may be able to protect headend reception.

Some of the NCTA proposals—a power cap on portable devices, the use of a geolocation database in some cases—resemble those of set-top box maker Motorola.