Crosstalk in Outside Plant Cable Systems

A transmission model of outside plant wire pair cable systems which includes direct crosstalk is developed here. We begin by presenting a deterministic model of outside plant systems by means of matrix representations of the various elements. The perturbation technique for handling pair-to-pair coupling is developed in detail. An adaptation of the model in the form of a simulation program is discussed and comparisons between simulations and experiments are made. A stochastic treatment of pair-to-pair capacitive coupling is given which is shown to lead to a method of optimal twist length selection. We stress that the theory we present here has its origin in the work of others (see, for example, Ref. 1 through 4). The ideas of direct crosstalk and of treating capacitance unbalance as random functions with 2421 2-132 T H E BELL SYSTEM T E C H N I C A L J O U R N A L , SEPTEMBER 1971 a delta function covariance are familiar to those who have worked on crosstalk. We organize and extend available techniques in the direction of furnishing a suitable systems engineering model of crosstalk. The transformation of our model into a practical engineering tool extends the use of routine data on pair-to-pair capacitance unbalance that are taken at Western Electric's cable manufacturing locations on a daily basis.