John E. Carroll; Frank H. Sanders; Robert L. Sole; Geoffrey A. Sanders

Abstract: In early 2009, the Federal Aviation Administration (FAA) became aware of interference to Terminal Doppler Weather Radars (TDWRs) that operate in the 5600–5650 MHz band and provide quantitative measurements of gust fronts, windshear, microbursts, and other weather hazards for improved safety of operations in and around major airports. This report describes field measurements and results from an examination of interference to a TDWR in San Juan, Puerto Rico from unlicensed national information infrastructure (U–NII) dynamic frequency selection (DFS) devices operating in the same frequency band. Several U–NII devices from different manufacturers were found to be causing interference into the TDWR. These devices operate in the same bands as these Federal radar systems, but employ DFS technology that is supposed to detect the presence of nearby radar systems and change operating frequencies to prevent interference with incumbent radar systems. This is the first of a three-part series of reports that describe research efforts by the Institute for Telecommunication Sciences (ITS) engineers, with assistance from FAA engineers, to determine the cause of the interference, understand why some devices fail to detect TDWR signals, and engineer solutions.

Keywords: radar interference; RF interference; radar performance degradation; unlicensed national information infrastructure (U-NII); spectrum sharing technology; terminal Doppler weather radar (TDWR); dynamic frequency selection (DFS)

For technical information concerning this report, contact:

John E. Carroll
Institute for Telecommunication Sciences
(303) 497-3367

To request a reprint of this report, contact:

Lilli Segre, Publications Officer
Institute for Telecommunication Sciences
(303) 497-3572

Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

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