Measurement of electromagnetic interference in time-domain

Abstract. Time-domain EMI measurement systems allow measurement time to be reduced by several orders of magnitude. In this paper a novel real-time operating time-domain EMI measurement system is presented. By the use of several analog-to-digital converters the dynamic range requested by the international EMC standards is achieved. A real-time operating digital signal processing unit is presented. The frequency band that is investigated is subdivided into several sub-bands. A novel implementation of the 9 kHz IF filter for the frequency 150 kHz to 1 GHz is presented. By this way the measurement time has been reduced by a factor of 8000 in comparison to conventional EMI receivers. During emission measurements performed with a modelled IF-bandwidth of 9 kHz the noise floor is decreased to −19 dBµV in the average detector mode by the implemented low noise power splitter. Measurements have been performed with the improved measurement system in the frequency range 30 MHz–1 GHz.