Time-domain just-before-test verification method to detect failures and ensure the measurement accuracy for conducted emissions and immunity tests

It is mandatory for EMC test laboratories to apply verification methodologies to ensure that they are performing the tests properly. However, the time-consumption of most of the procedures or its low accuracy causes low-impact and consequently a poor benefit for laboratories. With the aim to improve the performance of the current verification methods, a just-before-test methodology based on time-domain measurements is proposed in this publication. In order to improve the accuracy and detect failures for conducted emissions and immunity tests, arbitrary waveforms and full time-domain EMI measurement methods are combined. Hence, it is proposed to use multi-tone and pulsed waveforms to evaluate the performance of the conducted emissions test, including the receiver with normative detectors, paths and devices like LISN. On the other hand, for the immunity test, a time-domain EMI system based on the use of an oscilloscope is employed to identify defects on the amplifier, RF generator, devices like CDNs or paths. The methodologies are explained and validated through different simulated failure scenarios. Where we can identify a proper performance of the test bench or defects like poor grounding or coupling devices malfunctions.