The Type N-1 Carrier Telephone System: Objectives and Transmission Features

Abstract

The N1 Carrier System is a 12‐channel, double‐sideband system for single cable application. It provides low loss, stable, high velocity service for toll and exchange circuits in the range from 15 or 20 miles to 200 miles. Units and sub‐assemblies are miniaturized and arranged on a plug‐in basis. Emphasis has been placed on reduction in cost of components, as well as simplification of manufacturing methods, engineering, installation and maintenance. Economy is achieved by many novel features, principal among which is a built‐in low cost compandor. By compressing and expanding the volume range of speech, the compandor permits much higher tolerance of noise and crosstalk, thereby substantially lowering the cost of both line and terminal facilities. Other important features are self‐contained dialing and supervisory signaling, an individual channel regulator, and automatic equalization through the use of “frequency frogging,” or interchange of high‐ and low‐frequency groups at each repeater.