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 timedomain 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.