File:A comparison between power line noise level field measurements and man-made radio noise prediction curves in the high frequency radio band (IA acomparisonbetwe109457457).pdf

Radio frequency noise is often the limiting factor in the ability of a communications receiver to discern a desired signal from man made interference. The predominate man made radio noise source in the high frequency radio band is gap type breakdown discharges on electric power distribution lines. The International Radio Consultative Committee (CCIR) has published its Report 258 which predicts the level of man made radio noise in the business, residential, rural, and quiet rural environmental categories. This thesis compares field measurements of gap type breakdown discharge generated noise, made in the high and very high frequency radio bands, to CCIR Report 258 predictions. It is shown that CCIR noise-level predictions correspond to field measurements in the low end of the high frequency band. At higher frequencies the CCIR curve consistently predicts a lower noise level than was measured in the field. An explanation for the difference between field measurements and CCIR predictions is presented. A trend noticed in the noise amplitude versus receiver bandwidth data measurements is investigated and leads to the development of a receiver bandwidth adjustment matrix. Using this matrix the noise-power measurements made in one receiver bandwidth can be scaled to a different bandwidth.