New 12-channel carrier system for extended-area trunk and subscriber service

The design considerations and development of a 12-channel carrier system for trunk and subscriber service are described. The dual-sideband AM (amplitude-modulated) system uses one modulation step only and has a grouped and a stacked frequency allocation for use with and without repeaters respectively. Compandors supplied on an optional basis and the use of high-gain amplifiers make it advantageous to use wire and cable facilities at frequencies as high as 350 kc.