Engineering of T1 carrier system repeatered lines

The repeatered lines for the T1 carrier system (24 voice channels, PCM) are cable pairs equipped with transistorized regenerative amplifiers. The line signal is a train of 1,544,000 bipolar pulse positions per second. The line engineering methods, which tell how to select cable facilities and where to place repeaters, are based on the theory and measurements reported here. Using typical cable data, specific examples are given of the design limits imposed by the principal types of interference: crosstalk from other T1 systems and noise originating in central offices.