The Electromagnetic Disturbance on the Ethernet Ports of Telecommunication Equipments in Customer Premises

摘要

Recently both video and high-quality voice services have been provided by using Ethernet cables to connect telecommunication equipment with a set-top box (STB) or other IP-based communication device. As such services require low delays and a low frame error rate, any electromagnetic disturbance may strongly affect user satisfaction. Therefore, it is important to immunize the telecommunication equipment on customer premises against such signal interference. However, the required level of immunity for internal communication ports on telecommunication equipment, including Ethernet ports, has not been clarified. In this paper, we examine the entry of electromagnetic disturbances via the Ethernet ports of telecommunication equipment on customer premises. We found that electromagnetic disturbances in the 0.15 to 80 MHz range, which occur in AC power supply lines, may be attenuated by a few dB when transmitted through IP-based communication devices such as PCs, HUBs, and STBs, and may enter the Ethernet ports of telecommunication equipment at almost the same level as it appeared in AC power supply lines. Hence we should plan for disturbing waves at Ethernet ports that are as large as those in AC power lines when the immunity requirements for Ethernet ports are considered.