The N3 Carrier System: Objectives and Transmission Features

The N3 carrier system development completes the second phase of a comprehensive design program to provide a new family of short-haul carrier facilities. The system includes a 24-channel, single-sideband, amplitude modulated multiplex terminal, a common carrier supply, and an N-repeatered line. Associated development effort was directed toward the provision of a shop-wired, double-bay framework to combine the carrier terminals, voice-frequency patching jacks, signaling equipment, and automatic trunk processing facilities in one equipment package. Design objectives were established to meet today's and future stringent transmission performance requirements for direct, toll-connecting, and intertoll trunks. Taking advantage of the rapid growth in solid-state technology, significant transmission performance improvements have been achieved over earlier vacuum tube systems. In addition, installation, operating, and maintenance procedures have all been simplified. The system can be economically applied for distances as short as 35 miles, and with satisfactory transmission performance for distances exceeding 200 miles. A feature of special note is the provision of frequency correction units within the carrier terminal which essentially eliminates the frequency shift error introduced by the N-repeatered line.