FCC Cites Utah Broadband for FAA Radar Interference

Recently I received a complaint about interference from 5 GHz wireless devices making a New York City TV station's weather radar essentially unusable.

It turns out these devices are causing problems for FAA radars as well.

The FCC issued a Notice of Apparent Liability for Forfeiture and Order (DA 11-273) stating that Utah Broadband, located in Sandy, Utah, "apparently willfully and repeatedly violated sections 301 and 302(b) of the Communications Act of 1934, as amended, ("Act")2 and sections 15.1(b) and 15.1(c) of the Commission's rules ("Rules") by operating intentional radiators not in accordance with Part 15 of the Rules and the devices' Equipment Authorization."

Utah Broadband operated two Unlicensed National Information Infrastructure (U-NII) transmission systems in Salt Lake City.

The FCC said that it had acted on reports of interference to the FAA's terminal Doppler weather radar ("TDWR") installation that serves the Salt Lake City International Airport."

On Oct. 5, 2010, agents from the FCC's Enforcement Bureaus in Denver and San Diego, along with FAA personnel, used direction-finding techniques to locate emissions on the frequencies 5580 and 5640 MHz. The following day, the FCC and FAA used identical techniques to confirm that the interference was coming from two U-NII transmission systems located on the rooftop of the Brody Chemical Building in Salt Lake City.

The report noted further that during the inspection of the facility it was observed that the System 1 transceiver was operating on 5580 MHz and the System 2 transceiver was operating on 5640 MHz--both outside the authorized frequency band.

The FCC agents also observed--and Utah Broadband personnel acknowledged--that the required Dynamic Frequency Selection (DFS) functionality of each transceiver was disabled. [Devices operating in the U-NII bands are required to have DFS radar detection functionality to detect the presence of radar systems and to avoid co-channel operations with those systems.]

During the inspection, Utah Broadband adjusted the devices' operating frequencies to eliminate interference with the Salt Lake TDWR equipment.

The agents found the radios were also operating with high-gain antennas and had effective radiated powers in excess of Part 15 limits. (The Notice of Apparent Liability has more information on the system configuration.)

The FCC concluded that Utah Broadband was apparently liable for a forfeiture of $25,000 for rules violations.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.