Circuit Design of the N3 Carrier Terminal

During the late 1950's short-haul carrier systems began to undergo a comprehensive modernization program. The primary objective of this program was to achieve significant improvement in reliability and transmission performance of the short-haul family in order to meet higher standards for transmission of message, program, and data or other special services over intertoll trunks. Equally desirable improvements were sought in the areas of miniaturization, reduced maintenance, economical installation, lower power requirements, and flexibility. The first two phases of this program have been completed with the introduction of the N1A repeater and the N2 terminal -- a twelve-channel double-sideband system. The third phase, the N3 carrier terminal, is described from a circuit standpoint in this paper. The N3 carrier terminal, a new 24-channel single-sideband system, was designed to provide a considerable transmission improvement over its predecessor the ON2 system. It has been engineered to provide a 3-dB channel bandwidth between 200 and 3450 Hz and a net loss stability of ±0.5 dB over extreme operating conditions. A large part 801