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.