Crosstalk on Open-Wire Lines

Crosstalk 011 open-wire lines results from cross-induction between the circuits due to the electric and magnetic fields surrounding the wires. The limitation of crosstalk couplings to tolerable magnitudes is achieved by systematically turning over or transposing the conductors that comprise the circuits. The fundamental theory underlying the engineering of such transposition arrangements was presented by A. G. Chapman in a paper entitled Open-Wire Crosstalk published in the Bell System Technical Journal in .January and April, 1934. There is now available a Monograph (No. 2520) supplementing Mr. Chapman's paper which reflects a considerable amount of experience resulting from the application of these techniques and provides a basis for the engineering of open-wire plant. The scope of the material is indicated by the following: TRANSPOSITION PATTERNS This describes the basic transposition types which define the number and locations of transpositions applied to the individual open-wire circuits. TYPES OF CROSSTALK COUPLING Crosstalk occurs both within incremental segments of line and between such segments. Furthermore, the coupling may result from crossinduction directly from a disturbing to a disturbed circuit or indirectly by way of an intervening tertiary circuit. On the disturbed circuit the crosstalk is propagated both toward the source of the original signal and toward the distant terminal. A knowledge of the relative importance of the various types of coupling is valuable in establishing certain timesaving approximations which facilitate the analysis of the total crosstalk picture.