Multilevel Validation of Direct Sampling Time-Domain Measuring Receivers

Although the time-domain approach to electromagnetic interference evaluation offers numerous advantages, including shorter test duration and multichannel acquisition, its practical adoption remains limited. This is mainly because existing standards, such as CISPR 16-1-1, do not explicitly address direct sampling time-domain measuring receivers or define specific calibration and validation procedures for them. While several studies have demonstrated successful use cases, a comprehensive validation of such systems has not yet been performed. This article presents multilevel experimental validations of time-domain measuring receivers, focusing on the direct sampling approach and oscilloscope-based implementations. First, meta-comparisons of FFT-based receivers are made using calibration data obtained from certificates of accredited laboratories. Then, controlled signal sources with known time and spectral characteristics are used to cross-check with different measuring receiver models. Finally, several instruments are benchmarked with respect to their standard detector outputs when measuring the emissions of a power converter while spread spectrum techniques are used. The results show good agreement between the measuring receivers in the time domain and the tested conventional receivers in the frequency domain within the standard error, even though the complexity of the measured signals is different.