Measuring electromagnetic interference in time-domain in CISPR Band E and beyond

In this paper, a low-noise, high-dynamic time-domain EMI measurement system that allows for measurements from 9 kHz - 26 GHz is presented. Ultra-fast analog-to-digital-conversion and real-time digital signal processing on a field-programmable-gate-array (FPGA) are complemented with ultra-broadband multi-stage down-conversion. The system is fully compliant to CISPR 16-1-1. Measurements show, that the system exceeds the dynamic requirements of CISPR 16-1-1 by over 20 dB and allows for the measurement of high-dynamic range signals like radar pulses. The noise floor power spectral density is reduced to below -150 dBm/Hz. The resulting high system sensitivity allows for the real-time characterization of broadband, low-level signals near the noise floor in CISPR Band E. A scan from 9 kHz to 26 GHz with a 9 kHz IF filter bandwidth is completed in under 200 s, while over 5·10⁶ frequency points are calculated. Measurements of electronic consumer devices and electric household appliances above 1 GHz are presented.