Eliminating background noise in EMI test based on frequency-domain adaptive filtering

In non-standard test sites, background noise makes great influence to electromagnetic interference (EMI) measurements as a result of submergence of Equipment Under Test (EUT)´s own emission in the background noise. Accurate emission from a EUT is difficult to be obtained directly from measurement results. Focusing on this situation, this paper presents a method which eliminates background noise in EMI test based on frequency-domain adaptive filtering. Through the demonstration of adaptive filtering and the contrast between frequency-domain algorithm and time-domain algorithm, it obtains a frequency-domain adaptive filtering method that is suitable for EMI test. This method can acquire the signal strength of EUT´s own emission and ensure the accuracy of EMI test. As expected, the proposed method is proven to be more efficient and accurate through the results of simulation and measurement.