Radio interference from ignition systems

The paper records the results of some tests made in the United States to compare results obtained with American, German and British radio-interference measuring sets when measuring the interference radiated by the ignition systems of motor vehicles. The tests show the close agreement between the results obtained when using the various national measuring sets and confirm the reliability and consistency of measuring equipment conforming to the specification of the International Committee on Radio Interference (C.I.S.P.R.). They also attempt to establish a relationship between the results of peak and quasi-peak measurements. The paper also tabulates and discusses the test conditions specified in the various countries and quotes the limits of ignition interference recommended or statutory in the countries concerned. A direct comparison of these limits, which is made possible by these measurements, suggests that the existing and proposed requirements of other countries are more onerous than those of the United Kingdom.