Time-Domain Electromagnetic Interference Measurement System for intermittent disturbances

In Electromagnetic Compatibility emission measurements, a common problem takes place when equipment producing intermittent disturbances are measured according to standard procedures. In many cases, it is impossible to capture the maximum emission using conventional receivers with only one or several sweeps. A significant measurement improvement is possible when time-domain captures and post-processing implementing digital fast Fourier transform (DFT) is used to obtain the frequency spectrum. In addition, the time-domain method offers the possibility to capture all the spectrum frequency range of one single event and evaluate rapidly all the different functional modes of a complex EUT. In this paper, the time-domain method is described and validated for conducted emissions test. For the validation proposes, a multisine signal is measured using the developed method and the results are compared with results acquire from an EMI receiver. Finally, after validation, the time-domain method is applied to complex equipment observing the main advantages that the developed method provides.