Radiated ignition noise due to the individual cylinders of an automobile engine

It is known that mobile communication systems are susceptible to radio-frequency interference (RFI) generated by automotive ignition systems. In this paper the automotive ignition noise generated by individual engine cylinders is investigated. Using specially designed instrumentation, the pulse amplitude densities of individual cylinder ignition noise are measured and analyzed. It is found that the ignition noise generated by the individual cylinders is not statistically uniform and the modes of the pulse amplitude densities of different cylinders may differ by as much as 30 dB (as measured by an antenna positioned to one side of the vehicle). The measurement procedure and results discussed in this paper may prove to be valuable in the diagnosis of ignition system RFI.