Exploiting the Phantom-Mode Signal in DSL Applications

In order to meet the ever-increasing bandwidth demand of the users, new “digital subscriber line” (DSL) technologies are being developed. In addition to the traditional differential mode of the telephone line, telecom operators are now looking in to the exploitation of the phantom-mode signal. New transmission line models, using the multiconductor transmission lines theory, were developed to support this extended use. In this paper, it is shown that the phantom mode is an eigenmode of the quad cable system, and hence, according to the theory, there is no crosstalk between this mode and the differential mode.