Use and extrapolation of barrage measurements in formulating PCM planning rules

Planning rules for installing PCM systems on symmetric-pair cable have traditionally been based on cable crosstalk measurements taken on a pair-to-pair basis, and statistical methods have been used to predict the upper points, 99 or 99.9%, of a cumulative probability distribution of total interference power. Recently, more sophisticated measuring equipment has allowed cable measurements to be taken on a `barrage¿¿ basis, necessitating considerably fewer measurements being taken to characterise the cable. Interest in these methods has been shown by several PTT administrations and the use of barrage cable test equipment is likely to become widespread. Statistical methods are required to translate these barrage measurements into useful `planning rules¿¿, and the aim of this paper is to show how the statistical part of this process can be done, given some simplifying assumptions. The statistical techniques used here may well have applications in other areas of technology.