One in a series of pocket-sized guides selected from "The Telecommunications Engineers Reference Book", this book provides an analysis of theory and practice in telecommunications. It develops further the principles of transmission covered in the companion volume "Telecommunications Transmission Pinciples", describing transmission techniques, including the synchronous digital hierarchy, as well as other applications such as video and fasimile transmission. Also included is an analysis of the key components used within the telecommunications systems and the techniques used to measure its effectiveness.