A completely transistorized 600-channel multiplex system

The past 10 years have brought forth few improvements in long-haul telephone carrier systems, despite steadily-increasing consumer demands. Existing carrier systems were designed primarily for the transmission of speech and have been used mainly for that and for telegraphic transmissions. The common carriers, independents, and private and government-owned systems have done a remarkable job in providing new types of service such as handling of data, Teletype, and facsimile. However, costs have run high because of the need to derate capacities of systems designed primaily for voice transmission or to add suitable devices for correcting delay distortion, amplitude distortion, frequency stability, or signal-noise ratio.