A Novel Method of Ambient Interferences Suppressing for In Situ Electromagnetic Radiated Emission Test

A measurement method for adaptive interference suppression in in situ radiated emission test is proposed. First, the method obtained multichannel data to achieve the signal directions of arrival from equipment under test (EUT) and interference sources by the spatial spectrum estimation technique based on the multiple signal classification algorithm. Second, broadband minimum variance distortionless response (MVDR) beamforming algorithm combined with short time Fourier transform (STFT) was taken to form the beam pattern null traps in the directions of interferences, thus realizing the suppression on interferences. The factors affecting the accuracy of spatial spectrum estimation and the angular resolution of beamforming were discussed, and the suppression effects on different kinds of interferences were simulated. The simulation results show that the method can suppress multiple interferences, which are either narrowband or broadband, continuous or transient, and avoid little distortion to the time-frequency characteristics of EUT signal simultaneously. The method performance was evaluated by experiments. The results show that sine wave and pulse modulation interferences can both be suppressed remarkably, which proves the effectiveness and advantage of this new method for electromagnetic compatibility in situ test.