02.14.2005 01:43 PM
SBE warns commission not to ‘sow land mines’ on DTV superhighway

The Society of Broadcast Engineers has warned the commission that proposed rulemaking to allow higher power unlicensed Part 15 operation on “unused” television broadcast channels poses a serious threat of interference ENG operations.

In its filing, the society disagreed with several assertions from IEEE 802 and the New America Foundation. The SBE took issue with IEEE 802’s characterization of unlicensed Part 15 fixed base stations and customer premises equipment with transmitter power output of up to 1 watt (30dBm) and an effective radiated power or 4 watts (36dBm) as low power.

Such devices “inevitably cause interference” to Part 73 TV stations and Part 74 BAS (broadcast auxiliary station) operation. Based on experience with Wi-Fi, the society said “it wouldn’t be long before such base stations start showing up” at high elevations with line-of-sight to metropolitan areas.

The SBE, which described Part 15 devices as being at the “bottom-of-the-RF-food-chain,” also questioned the practicality of having an FCC representative notify users of offending Part 15 devices of interference because of the limited number of FCC Enforcement Bureau offices and staff.

It pointed to the use of wireless mics in an ENG application as an example of the impracticality of the proposal, saying “any time delay in shutting down an in-the-way Part 15 system operating on a supposedly unused TV channel would be unacceptable.”

The society also characterized a proposal to install a “no Part 15” beacon in the equipment of Part 74 licensees as a “cost which BAS licensees should not be required to bear” and ultimately as “UUI: Unrealistic, Unenforceable, and Impractical.”

The society asserted that IEEE 802 proceeded from the mistaken idea that Part 15 systems would have no obligation to protect the signal of a TV or DTV station outside its protected contour. Pointing to existing commission rules governing secondary services, such as LPTV, that protect primary TV licensees from interference outside their protected contour, the society contended that “it does not matter whether the interference is inside or outside” the primary station’s protected contour.

Turning to comments form the New America Foundation (NAF), the society told the commission that NAF’s comments “cavalierly” dismiss the threat to BAS operation, “characterized the priority of expanded Part 15 operations as co-equal with licensed LPTV stations” and “show a breathtaking lack of engineering reality or common sense.”

The SBE comments warned the FCC that its rulemaking is “toying with Pandora’s Box” and that to let higher power Part 15 devices be marketed for use on “unused” TV channels “would be the equivalent of sowing land mines on the DTV superhighway.”

For more information, visit www.sbe.org.

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