Intelligible Crosstalk Performance of Voice-Frequency Customer Loops

Abstract

A methodology for evaluating the intelligible crosstalk performance of voice‐frequency customer loops is developed in this paper. Using this methodology, intelligible crosstalk probabilities are calculated for a representative sample of loops in the plant. The effect of gain on loop crosstalk performance is then evaluated for a particular example of gain application where length‐dependent gain ranging approximately from — 1 to 9 dB is added. Two possible locations of gain application are evaluated: the central office and the telephone set. Presently, no crosstalk performance objectives exist for loops. For planning purposes, however, an intelligible crosstalk probability of 0.1 percent has been used in the past as a limit for satisfactory performance. In comparison with this limit, the crosstalk performance of the present loop plant (loops without gain) is satisfactory. For the particular example of gain application considered in this paper, gain applied at the central office has only a small effect on loop crosstalk performance. However, gain applied at the telephone set degrades loop crosstalk performance significantly, increasing the crosstalk probability above the 0.1 percent level on about 15 percent of the sample loops evaluated.