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FCC Fines AT&T $25,000 for Errant Broadband Transmitter

WASHINGTON: The Federal Communications Commission has fined AT&T $25,000 for operating an unlicensed wireless broadband transmitter that was interfering with an aviation weather radar system. The transmitter, a Motorola Canopy, was located on the roof of the Miramar Plaza Condos in Santurce, Puerto Rico. It was interfering with Federal Aviation Administration’s Terminal Doppler Weather Radar system serving the San Juan International Airport.

The commission’s Forfeiture Order said AT&T was using the Canopy as an Unlicensed National Information Infrastructure device on an unauthorized frequency at 5,605 MHz. Commission agents used direction-finding gear to track the emissions to the Canopy, which is certified as a Part 15 radiator at 5,735 to 5,840 MHz only, and not for U-NII use. The device is also not capable of dynamic frequency selection, which allows U-NII radiators to jump out of the way of FAA radar systems. AT&T argued that its transmitter was operating in the authorized band and not the source of the interference. However, field agents found otherwise.

“The On Dec. 8, 2010, the agents took measurements directly in front of the Motorola Canopy transmitter, later identified by AT&T employees as an AT&T device, and recorded the spectral display of the transmission on 5,605 MHz,” the Order stated. “The spectral images show a strong signal on 5,605 MHz, and no signal on 5,685 MHz. On Dec. 8, 2010, agents from the San Juan Office were present when AT&T’s transmitter stopped transmitting on 5,605 MHz. At that point, the interference to the San Juan TDWR noticeably decreased.”

AT&T’s fine was part of a wider sweep by the FCC’s Enforcement Bureau toward “several companies for operating devices that caused interference to Terminal Doppler Weather Radars” maintained by the FAA.

“Much of the interference stems from wireless devices sharing the same band as TDWR systems, and operating outdoors in the vicinity of airports at high elevations that are line-of-sight due to the TDWR installations, and most are operating inconsistent with FCC Part 15 Rules,” the related Enforcement Advisory said.

U-NII devices must have dynamic frequency selection capabilities.

“A piece of equipment is no longer certified as required under the FCC rules if it is installed or configured to defeat DFS, to utilize antennas other than those certified for the device, or to make other changes that modify the equipment beyond the configuration that has been certified,” the Advisory said. “Using uncertified U-NII devices, or certified U-NII devices in an unauthorized manner, violates the FCC Part 15 Rules and may result in interference to radio communications services critical to public safety.”