Prediction of Relative Available Noise Power for Vehicular Ignition Noise

A high frequency radio noise model was developed for predicting average electromagnetic noise (EMN) lev­ els, in terms of Fa, from a number of vehicles travel­ ing on a roadway. The model, which is based on a vehi­ cular ignition noise model previously developed by A. D. Spaulding, predicts average Fa levels as a function of traffic density and distance from the roadway. Meas­ urements of the EMN level variations with respect to vehicular make, distance, frequency, orientation of the vehicle, number of cylinders, and engine RPM made on a sample of individual vehicles, supplemented with meas­ ured ignition noise data from published studies, were used for assessing and determining relationships for the model development. Predicted average Fa levels for freeway traffic conditions were within 4 dB of measured results.