October 2012 | NTIA Technical Report TR-13-490
Frank Sanders; Robert L. Sole; John E. Carroll; Glenn S. Secrest; T. Lynn Allmon
Abstract: This report describes the methodology and results of an investigation into the source, mechanism, and solutions for radiofrequency (RF) interference to WSR-88D Next-Generation Weather Radars (NEXRADs). It shows that the interference source is nearby base stations transmitters in the Broadband Radio Service (BRS) and the Educational Broadband Service (EBS) and that their out-of-band (OOB) emissions can cause interference on NEXRAD receiver frequencies. The methodology for determining interference power levels and mitigation solutions is described. Several technical solutions that can mitigate the problem are shown to be effective. Trade-offs between effectiveness, difficulty, and costs of various solutions are described, but it is shown that there is always at least one effective technical solution. The report shows that careful planning and coordination between communication system service providers and Federal agencies operating nearby radars is important in the implementation of these interference-mitigation techniques. A number of the report’s interference mitigation options have already been implemented in several United States cities served by a BRS/EBS licensee, at licensee WiMAX stations where NEXRAD radar operations are located nearby. As of the date of this report’s release, interference from the licensee’s WiMAX links to NEXRAD receivers in those markets has been successfully mitigated using the techniques described herein.
Keywords: electromagnetic compatibility (EMC); radar interference; radio frequency interference (RFI); out-of-band (OOB) emissions; airport surveillance radar (ASR); NEXRAD; WiMAX; WSR-88D; interference-to-noise (I/N) ratio
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Frank H. Sanders
Institute for Telecommunication Sciences
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.