The Evaluation Method of Electromagnetic Disturbance and Interference on Ubiquitous Equipment

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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.