Electromagnetic Interference and Countermeasures on Metallic Lines for ISDN


IEICE TRANSACTIONS on Communications   Vol.E75-B    No.1    pp.50-56
Publication Date: 1992/01/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electromagnetic Compatibility
EMC,  induced voltage,  noise,  error,  ISDN,  basic interface,  

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Electromagnetic interference on a bus wiring configuration of the ISDN basic interface using metallic telecommunication lines is studied. A simple circuit to simulate terminal equipment unbalance about earth is developed for measurement purposes, based on the fact that the unbalance weakens the withstanding capability against interference. The electromagnetic interferences from low-voltage supply lines, analog telephone lines and broadcasting waves are evaluated by experiments using the circuit. The interference is measured by both induced voltage on the interface line and the error rate of the transmission signal line. Consequently, it is clarified that the basic interface is disturbed by the induced voltage, because the terminal equipment in the CCITT Recommendation I.430 has too large an unbalance about earth to maintain transmission quality. Adding to this, countermeasures to reduce interference are proposed.