EMI pre-measuring system on supply line conducted interference based on spectrum analyzer

With the implementation of China Compulsive Certification (CCC), more and more manufacturers realize that they must improve their product quality on EMC. In this paper, one system of electromagnetic interference (EMI) pre-measuring is developed to meet the product designer´s demand for EMI diagnoses. The system is applied to measure the unsymmetric interferential signal of supply line quantitatively based on the spectrum analyzer, line impedance stabilization network (LISN) and automatic test system. The structure of the test system is described firstly. Then the circuit diagram of V-LISN for the unsymmetric interferential signal test is showed. A designing method of automatic test system based on LabVIEW is commented in detailed. At last, a test is carried out to demonstrate the system is rational and applied.