The New McGraw-Hill Telecom Factbook, Second Edition
A plain-English guide anyone can use to plan and acquire telecommunications products and services!
TABLE OF CONTENTS The New McGraw-Hill Telecom Factbook, Second Edition
Chapter 4: Transmission System Concepts
Overview
Building on definitions and basic concepts presented thus far, the next four chapters treat transmission, multiplexing, circuit-switching, and packet-switching concepts in substantial detail. As noted in Chapter 1, transmission facilities provide communication paths that carry user and network control information between nodes in a network. In general, transmission facilities consist of a medium and various types of electronic equipment located at points along transmission routes. This equipment amplifies or regenerates signals, provides termination functions at points where transmission facilities connect to switching systems, and often includes means to combine many separate sets of call information into single multiplexed signals to enhance transmission efficiency.
Transmission Media
A transmission medium is any material substance or free space, (i.e., a vacuum) that can be used for the propagation of suitable signals, usually in the form of electromagnetic (including lightwaves) or acoustic waves, from one point to another; unguided in the case of free space or gaseous media, or guided by a boundary of material substance. Guided media, including paired metallic wire cable, coaxial cable, and fiber optic cable, constrain electromagnetic or acoustical waves within boundaries established by their physical construction. Unguided media are those in which boundary effects between free space and material substances are absent. The free space medium may include a gas or vapor. Unguided media including the atmosphere and outer space support terrestrial and satellite radio and optical transmission. This section provides brief descriptions of and defines terms associated with prevalent media. Later sections discuss how...
Copyright The McGraw-Hill Companies, Inc. 2000 under license agreement with Books24x7
