Application-specific near field EMI estimation on time-sharing operating system

Abstract

This paper proposes a measurement-based method to estimate application (APP) specific EMI on a device running a time-sharing multi-tasking operating system (OS). The proposed method includes a near-field measurement technique for APP-specific EMI and an algorithm which can estimate system EMI with any different APPs execution sequences. Because of the task-scheduling feature, the execution order of APPs inside a system is dependent on various factors. Thus, the EMI estimation of such system may be complex. In this paper, the proposed method selects an OS and two APPs as a case study. The OS used in this paper is an open-source OS for robotic control with a commercial microcontroller. The measurement results show good agreements in the different execution orders of these 2 APPs. From 40MHz (system clock rate) up to 1GHz, the maximum difference is 4 dB within the range. This method can be used to estimate near field EMI of a complex HW/SW system.