MEASUREMENT PARAMETERS FOR AUTOMOBILE IGNITION NOISE

Peak-detector measurements of radiated electromagnetic noise from automobile ignition systems reveal detectable frequency components over a range to 7 GHz. Occasionally a very noisy vehicle will radiate noise over the entire frequency range in excess of 30 dB above the median observed noisy vehicle. Subjective evaluations indicate that the landmobile radio service may possibly by affected by automobile ignition noise. Automobile ignition noise is typically measured using a radio noise meter equipped with either a peak detector or a quasi-peak detector, and has also been measured using special equipment to produce the average rate of occurrence and strength of noise impulses. The result of the latter measurement is referred to as a noise amplitude distribution (NAD). Since the NAD method includes a measurement of the time variations of the ignition noise process, it is superior to the first-order amplitude measurements obtained by the peak or quasi-peak method for modeling the effects of ignition noise on communication systems. Ideal and practical modeling methods are discussed for determining the effect of ignition noise upon communication systems, with emphasis on voice communications. /Author/