Local networks

The local network is briefly described and three problems are posed: establishing an acceptable standard of performance, providing local planning engineers with a sound basis for economic calculation, and determining the quantity of plant to be provided. The standard local telephone circuit is described, and methods of assessment of the transmission performance are referred to. This leads to the methods of determination of line planning limits for design purposes in the local network. The basic principles of engineering economic cost comparisons at present used in the Post Office are described. Methods of forecasting growth and of providing a flexible system to meet fluctuations in the demand for telephones are described. A brief section on the more efficient use of the network at audio frequencies is included, and the paper concludes with consideration of the use of the network at carrier frequencies. Various uses, e.g. subscribers´ carrier, wired-broadcast services, data collection and alarm concentration, are mentioned. The transmission properties of the existing local network at carrier frequencies are given and conclusions drawn as to the limitations on its use for various methods of working. A final Section deals with the possible future use of the network at carrier frequencies.