Signal processing for generation of complex multiport transfer functions from medium quality time-domain measurements

Circuit feedback coupling by power supply lines is an important EMC issue. A modular multi-port network analyzer was developed to evaluate line coupling in a complex environment. The frequency range of interest was lower than 500 kHz however measurement time had to be kept low. Therefore a measurement solution in time domain was selected. The resulting data was to be used for system simulation in time and frequency domains. The set-up for a multi-port network analyzer is described in this paper and is used as an example. The measurement data of this analyzer is of medium quality. Therefore signal analysis is necessary to produce reliable input data for simulations. The main emphasis of this paper is to describe the steps of signal processing from experience. The results of simulation based on this data are compared to direct measurements.