Robert J. Matheson

Abstract: Measurements of the amplitude probability distributions and the average crossing rates of the electromagnetic noise radiated by automotive ignition systems were made at 30 MHz, 47 MHz, 147 MHz, 224 MHz, and 445 MHz. The ignition noise from a single car and a 12-car matrix were each measured in a 10 kHz bandwidth, using a field-intensity meter, a DM-4, a desktop calculator, and an X-Y plotter. The DM-4 is an instrument built by NTIA to measure amplitude probability distributions and average crossing rates. Numerical integration of the amplitude probability distributions was used to determine the rms, the average, and the average logarithm of the envelope of the measured noise.

Keywords: automotive ignition noise; electromagnetic noise; noise measurement; amplitude probability distribution

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Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

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