Preliminary Measurements on the Geography of Urban VHF Radio-Frequency Noise
Engineer Research and Development Center (U.S.) Hanover United States
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Radio-frequency RF noise has typically been measured at a handful of fixed, representative locations within the urban environment Achatz, Lo, Papazian, Dalke, and Hufford, 1998 Achatz and Dalke, 2001 Dalke, Achatz, Lo, Papazian, and Hufford, 1997 Wepman and Sanders, 2011 Wagstaff and Merricks, 2005 Spaulding and Disney, 1974. In this work, we discuss the development of a mobile RF noise measurement system and the necessary geospatial and statistical post-processing techniques required to characterize the variations in noise on the street-scale in the VHF sections 60 300 MHz of the spectrum. We discuss the design of our mobile noise measurement system, with special focus on the choice and calibration of preselection filters and preamplifiers necessary to reliably measure low RF noise levels while avoiding intermodulation distortion problems that arise in an environment with many strong emitters. Additionally, we describe post-processing techniques developed to reliably merge and interpolate the RF data with geolocation data which are collected on two very different microsecond and multisecond, respectively timescales. We use a preliminary urban dataset from Boston, MA to show that the geo-statistical properties of RF noise power can vary appreciably over street-scale distances, and that these spatial variations are repeatable over tactically relevant times.
- Radio Communications
- Radiofrequency Wave Propagation