Report: Ultrawide band devices interfere with GPS

Computerworld - A new report bolsters the safety concerns raised by the airline, cell phone and television broadcasting industries on the use of ultrawide band (UWB) wireless technology, which was hailed a year ago by the Federal Communications Commission for its ability to provide broadband services by piggybacking on spectrum occupied by wireless services.

The issue is that UWB devices spread signals across a broad swath of spectrum, which raises serious concerns about interference with other systems. On Friday, the National Telecommunications and Information Administration (NTIA) issued a report that airline and Department of Transportation officials said raises serious concerns about potential interference to Global Positioning Systems (GPS) that the Federal Aviation Administration plans to use for all stages of controlled flight, including landings.

UWB devices are short-range transmitters used for applications such as wireless LANs. UWB has the potential to provide short-range, high-speed wireless data transmissions that could make access to Web pages over the air as fast as a wired connection would be.

The report concluded that some UWB signals examined in recent tests "exceeded measured GPS performance levels" at output levels "well below" other unlicensed devices, such as cordless phones. The report also warned that UWB devices need to operate at very low emission levels to avoid interference with GPS signals.

The NTIA will forward its report to the FCC, which has considered since last May whether to approve the use of UWB. (see story)

James Miller, senior staff specialist for flight operations technology at United Air Lines Inc., said the NTIA report should serve as a sharp warning against any plans to license UWB devices for use on the GPS 1.2- and 1.5-GHz bands, which are used to control the flight and landing of aircraft. The report and the tests "show that there is interference with critical safety-of-life systems," Miller said. "It's not in the best interest of aviation to experiment with UWB in the GPS bands. The bottom line here is, Is there anyone in the government who will stand up and say we should use UWB in safety of life bands?"

Joe Canny, deputy assistant secretary for navigation system policy at the Transportation Department , said the NTIA report "demonstrated there are some serious problems between some types of UWB and GPS receivers. The test showed UWB can cause interference at power levels below that which had been proposed by the FCC."

Jeff Ross, vice president for corporate development strategies at Time Domain Corp. in Huntsville, Ala., which has championed UWB technology, said the company is