Communications and microwave: Fiber optics, solid state, and digital techniques boost transmission efficiency

Inspired by growing demand while contained by the limits of bandwidth, physical plant, and esthetics, the telecommunications industry made important progress in 1974 toward providing increased traffic density and improved message-handling capability. Significant advances were made in the promising art of fiber optic communications; improved electronic systems became available for branch exchanges and switching centers; and new hardware and software for digital encoding promise lower-cost, lower-data-rate digital transmission of voice signals.