A Simplified 48-Channel Carrier Telephone System
L. G. Erickson · Transactions of the American Institute of Electrical Engineers · 1950
This paper describes a 48-channel single side band carrier system which provides toll quality telephone transmission bands with exceptional simplicity and dependability of equipment. Through the use of a novel frequency translation pattern, speech bands covering the range from 200 cycles to 3,500 cycles are secured at 4-kc channel separation without resort to crystal filters. In this system, improved translating modulator techniques and other advanced features reduce the number of vacum tubes to a minimum while achieving exceptionally high performance standards, stability, and ease of maintenance.