WASHINGTON-Government testing of potential interference between the global positioning system and ultra-wideband devices seems to be politically inconclusive, while an UWB-industry funded study shows that UWB devices do not interfere any more than other unlicensed RF-using products.
“The report documents the results of the measurement and analysis program conducted by [the National Telecommunications and Information Administration]. Policy recommendations and/or guidance with respect to proposed UWB operations are not included within the scope of this effort,” said NTIA in a report posted on its Web site Friday morning.
An analysis by the Johns Hopkins University’s Applied Physics Laboratory that was funded by Time Domain Corp. also was released on Friday.
Time Domain, whose founder holds key UWB patents, has aggressively lobbied the Federal Communications Commission to approve UWB devices.
“The theoretical analysis and statistical data evaluation show that properly time coded UWB signals can be produced that have characteristics similar to white noise within the GPS frequency spectrum,” said the JHU-APL executive summary.
Time Domain obviously was ecstatic about the JHU results and guarded about the NTIA results.
`This analysis confirms that UWB would have no more impact on GPS than the millions of unlicensed devices and billions of digital devices that already safely co-exist with GPS. Moreover, the analysis proves unequivocally that the effect of emissions from multiple UWB devices is identical to the effect of emissions from multiple digital devices that comply with [FCC] rules. … We will examine the NTIA results and provide comments to the FCC as they relate to the notice of proposed rule-making for UWB technology,” said Jeffrey L. Ross, Time Domain vice president of corporate development and strategy.
Ultra-wideband, or pulse technology, uses short low powered and fast (up to one-trillionth of a second) pulses to transmit digital data over a range of frequencies. UWB technologies have long been recognized as the technology of choice for ground-penetrating radar. UWB is being recognized as a technology with the potential to address a far wider range of radar, communications and positioning applications including connecting mobile-phone calls directly to the landline network when the call is placed inside a building.
The aviation community has expressed concern that UWB technologies cause interference with GPS systems, but the results released by NTIA did not include testing of aviation GPS receivers.
“Due to unanticipated delays in the execution of the measurement component of this study, the measured data for the [aviation] receiver were not included in this report. This data will be provided as an addendum to this report as it becomes available,” said NTIA.
The FCC will put out the NTIA and JHU studies for public comment. As other information becomes available like the aviation studies and a Department of Transportation-funded study by Stanford University, this too will be put out for comment.
NTIA said in January that testing showed that UWB systems “have the potential”‘ to operate in the unrestricted non-GPS 3 to 6 GHz bands even though the power may exceed the interference protection criteria for unlicensed devices. The NTIA tests focused on the impact of UWB on federal systems from 400-6000 MHz bands, although no tests were performed in the 3-6 GHz bands. NTIA believes the potential exists for UWB based on analysis of tests done in the lower bands. Notwithstanding the NTIA’s belief that a potential exists for UWB at 3-6 GHz, the agency said it would be negotiating mitigating factors with the FCC.
Time Domain believes the release of the GPS tests means the FCC can move forward in establishing rules for the operation of UWB devices.
“With the release of the JHU-APL and NTIA GPS reports, the FCC now has sufficient data with which to formulate rules to enable the deployment of UWB without risk of harmful interference to critical safety-of-life applications,” said Ross.
The FCC and NTIA, during the Clinton administration, were in a public food fight over how much control NTIA could exert over UWB rules.
In its report released Friday, the agency again seemed to be asserting jurisdiction and the FCC confirmed on Friday that it would be coordinating at the staff level with NTIA staff on UWB rules.
The FCC began studying the issue in September 1998 and proposed rules in May that would impose few restrictions on the operating frequencies that UWB may use. The NPRM envisioned that government-sponsored testing of UWB would be completed by the end of 2000, but that deadline was not met due to funding and technical considerations.
Three companies-Time Domain, U.S. Radar Inc., and Zircon Corp.-received waivers from the FCC in June 1999 to begin deploying UWB technology.
