A rare text dedicated to high-performance measurement techniques in modern communications. It describes high performance measurement techniques for digital communications and digital signal processing in radio and microwave systems, wire line channels, as well as measurements for analog communications channels. AUTHOR'S COMMENTS The purpose of this book is to present the engineering considerations necessary for the comprehension of modern telecommunication measurement and related instrumentation and analysis techniques. I wish to emphasize that this is not an academic book in the sense of analytical communications or measurement theory. Rather, it stresses the measurements, experimental analysis and instrumentation problems related to communications systems. PUBLISHER'S COMMENTS This book provides a strong foundation for understanding the special problems associated with testing modern communications systems. Its original publication anticipated the needs of communications engineers, setting a foundation for current work. The book's continued availability assures that new engineers will have access to a key reference text in this important area of technology.