Investigation of Telecommunication Cabling Relevant to EN 55022 Modem Test Method

Traditional modems deployed over telephone cabling use only voice frequencies. DSL (Digital Subscriber Line) modems use radio frequencies over telephone cabling. EMC compliance of both traditional and DSL modems is tested using the same test method described in EN 55022. The development of enforcement standards such as MPT 1570 suggests that the method is giving an inadequate level of protection for DSL modems. This paper investigates mode conversion on cable/test transducer pairings by both a simple analysis and a more complex multi-conductor approach. Reasonable agreement is found between the methods, and modifications to the EN 55022 test method are proposed.