Evaluation of the LCLs of metallic cables in customer premises and immunity of VDSL systems

摘要

This paper describes a number of tests of the longitudinal conversion loss (LCL) of metallic cables and the immunity of VDSL systems. The LCL of metallic cables depends on the structures and configurations of the cables. In previous studies based on ITU-T recommendations, the metallic cables used for the measurement of LCL and immunity were set up on the ground reference plane. However, in practice, metallic cables in customer premises are rarely laid on the ground plane or near metal materials. In this paper, the LCL of metallic cables and the immunity levels for VDSL systems related to different cable structures (single-layer, twisted-pair, and star-quad cables) and different cable configurations (straight, folded, and coiled) have been evaluated for various distances between the metallic cable and the ground reference plane.