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Radio-frequency (RF) background noise is an important parameter in designing and predicting performance of RF communication and sensor systems. Modern man-made RF noise consists of unintentional emissions from sources such as electronic devices, power transmission lines, and internal combustion engine ignitions. Governments and academia have previously measured RF noise at fixed, representative locations within the urban environment. Considering the heterogeneous mix of office buildings, retail and residential buildings, transportation hubs, and parks that compromise modern cities, we hypothesize that RF-noise power varies significantly throughout the urban environment. To characterize this variability, we present a mobile, tunable RF-noise measurement system designed to record frequencies from 63 MHz to 1 GHz in a 1 MHz to 10 MHz bandwidth. This report describes the system design, including the choice of preselection filters, preamplifiers, and RF shielding necessary to measure low RF-noise levels while avoiding intermodulation distortion problems that arise in an environment with many strong emitters. Additionally, we describe techniques developed to reliably geolocate RF data in urban environments. GPS (global positioning system) reception is often poor in dense urban environments. We mitigate this issue by using a 1 m surveying wheel for geolocation. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/CRREL TR-19-8 iii

Measuring very high frequency and ultrahigh frequency radio noise in urban environments : a mobile measurement system for radio-frequency noise