Desenvolupament d'un sistema de mesura EMI basat en un osciloscopi

In Electromagnetic Compatibility emission measurements, and particularly the emissions tests, a common problem takes place when equipment producing intermittent disturbances is 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. This work aims to study and propose a measurement method that provides a solution to this problem A significant measurement improvement is possible when time-domain captures and post-processing implementing fast Fourier transform (FFT) are used to obtain the frequency spectrum. In addition, the proposed time-domain method offers some advantages as 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, the cost and the possibility to do a pre-analysis of the interference before the measurement. In this report, the time-domain method is described and validated for conducted emissions test. For the validation proposes, a multisine signal and other equipment are 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.