The Evaluation Method of Electromagnetic Disturbance and Interference on Ubiquitous Equipment

近年来，人们对设备内/设备间的电磁干扰问题进行了研究，特别是对普适设备等小型数字设备的电磁干扰问题。设备内干扰是指设备的发射干扰到设备本身的另一部分电路，这种干扰导致设备的性能下降。为了评估电子设备在噪声下的性能退化，为了避免误码率的测量困难，测量了通信性能“吞吐量”。本研究采用近场电磁干扰下的吞吐量来测量性能退化，并将结果与设备发射进行了比较，结果吻合较好。为了建立性能退化的评价方法，对电磁干扰下的通信指标进行了测量。从测量结果中，可以在一定程度上得出近场测量与性能下降的关系。这些事实使我们能够通过测量设备的近场发射来预测PCB上电磁干扰应用下的薄弱区域，反之亦然。为了减少设备内部干扰的风险，无论是电路板上的零件布局，还是设备内电路板的布局，都要做好这方面的管理。应当理解，所述电路具有上述类似的发射和抗扰特性。功能相近的电路最好分开放置，以避免电磁耦合。在进一步的工作中，应明确设备内部干扰产生的机理，并研究减少干扰的技术。

Recently the electromagnetic interference of intra/inter-equipment has been studied, especially on the small digital device such as ubiquitous equipment. The interference of intra-equipment means that an emission form the equipment interferes to another part of circuit on the equipment itself and this interference causes performance degradation of the equipment. To evaluate the performance degradation of the electronic equipment exposed to the noise, the communication performance, "through-put", was measured in avoiding measurement difficulties of BER(bit error rate).In this study, the performance degradation was measured using through-put under near field electromagnetic disturbance, and the results are compared with the emission from equipment, and good agreement was obtained. To develop the evaluation method of the performance degradation, some communication indexes were measured under EM(electromagnetic) disturbance. From the measured results, the relationship between near field measurement and performance degradation could be obtained in some extent. These facts enable us that the weak area under the EM disturbance application on PCB can be foreseen by measuring the near field emission from the equipment and vise versa.To reduce the risk of the intra-equipment interference, the layout of the parts on the circuit board and also the layout of the circuit boards in the equipment should be well managed in this aspect. It is understood that the circuit has similar characteristics of emission and immunity as mentioned above. Circuits having similar function had better to be located apart each other to avoid electromagnetic coupling.In the further work, the mechanism about the interference of intra-equipment should be cleared and the reduction technique for interference should be investigated.