Urban Radiofrequency Noise field spatial measurements at HF (25.5 Mhz) from Boston, MA October 2022

Radiofrequency noise measurements collected in Boston, MA. Data were collected using a mobile bicycle RF system in a large spatial survey. Data is organized spatially (lat, long coordinates). Data were collected at a center frequency of 25.5 MHz (~11.8 m) in 0.2 sec duration files. This frequency is near the top of the HF band and belongs to the unoccupied radio astronomy band specified by ITU-R RA.314-10. The recording bandwidth was 1 MHz. The internal noise floor of the system was measured to be -99.3 dBm with a standard 50 Ω load. A calibrated noise source with Excess Noise Ratio (ENR) of -16.4 dB at 25.5 MHz was used to obtain the noise figure of the recording system. A noise figure of 18.8 dB was estimated using the Y-factor technique.Columns: Epoch Time = time of measurement in number of seconds (including fractional seconds) elapsed since 00:00:00 1-Jan-1970 UTC Long (decimal) = Longitudinal position of measurement in decimal convention.Lat (decimal) = Latitude position of measurement in decimal convention.Power (dBm) = Average (median) RF power of each 0.2 noise file, expressed in decibels relative to 1 milliwatt in a 50 Ohm system.