Time-domain EMI measurement methodology

With substantial progress in Internet of things (IoT), new challenges of EMI on IoT (IoT-EMI) measurement have emerged. The IoT-EMI behaviors are complex and dependent on the target´s interactions between hardware and software. A systematic method for IoT-EMI measurement should be developed. However, the characteristics of IoT-EMI are digitally-controlled, time-varying, and software-dependent and make the IoT-EMI measurements difficult by conventional method. This paper proposes a time-domain measurement method for such issue. This method uses a `timestamp´ by SW/HW-co-measurement strategy to analysis IoT-EMI behaviors. From the measurement result, the long-term measurements are comparable to the conventional SA measurements. And the software-related IoT-EMI results show tremendous differences - about 5-50 dBuV differences among different application programs are observed. To the best of the authors´ knowledge, the software-dependent IoT-EMI behaviors are firstly observed and published.