This book explains the fundamentals of transmission lines and how radio waves, electrical circuits, and optical signals transfer information through a communication medium or channel on carrier signals. It also explains the ways that a single line can be divided into multiple channels and how signals are carried over transmission lines in analog or digital form. Find out how the transmission of information can be distorted by noise and distortion impairments and how error detection and correction techniques used in digital transmission can improve the performance of transmission lines. You will learn how some of the energy of signals transferred through transmission lines may leak out and be transferred to other lines causing crosstalk. Described are the basic types of in-band and out-of band signaling methods used on transmission lines. This includes multifrequency (MF), dual tone multifrequency (DTMF), and common channel signaling (SS7) methods. Covered are the basic transmission systems used in local transmission loops including plain old telephone service (POTS) analog lines, integrated services digital network (ISDN) digital lines, and digital subscriber line (DSL) technology. Described are the different types of multi-channel lines including electrical T1, E1, DS3 and optical carrier OC-1 to OC-768. You will learn how transmission systems use and benefit from repeaters and virtual connections.