Time-domain EMI Measurements at Open Test Sites using Ambient Noise Cancelation Methods

Time-domain as well as frequency domain adaptive filter algorithms have been investigated and compared in respect of their capabilities of suppressing ambient noise during time-domain measurements of electromagnetic interference at open test sites. The fundamentals and the application of the most advantageous algorithm for time-domain EMI measurements is described in this paper. An advanced digital signal processing technique for fast measurements of electromagnetic interference from electronic devices is presented. Measurements of electromagnetic interference of a device under test can be performed in a test site polluted by electromagnetic ambient noise by using digital signal processing. Frequency domain adaptive filtering using the overlap-save method is applied and measurement results of a real device under test are carried out showing the successful cancelation of ambient noise at an urban test site in a broad frequency range up to 1000 MHz