providing up to nearly 1 GHz of bandwidth at customer premises. It was originally a unidirectional system, from the point of origin, which we will call the headend, toward customer premises, providing from 20 to some 100 television channels. A CATV headend inserts signals into its transmission system for delivery to residences and offices (see Figure 17.1) from off-the-air local stations, satellite, LOS microwave, and locally generated programs. In older configurations, transmission systems consisted of coaxial cable with wideband amplifiers spaced at uniform distances. Current configurations consist of a headend feeding fiber-optic trunks up to hubs which convert the signal format to traditional coaxial cable for the last mile or last 100 feet. HE = headend D = drop wire to residence MW = microwave connectivity Figure 17.1 An early CATV system. The transmission line from the headend to subscribers is coaxial cable. The microwave extended the "reach" of the system to distant TV emitters. Fundamentals of Telecommunications, Second Edition, by Roger L. Freeman ISBN 0-471-71045-8 Copyright © 2005 by Roger L. Freeman COMMUNITY ANTENNA TELEVISION (CABLE TELEVISION) CATV does have the capability of being a two-way system and many CATV opera- tors are implementing such capability. The CATV band is actually the radio frequency band topping off at about 1000 MHz (see Figure 2.6, Chapter 2, from about 1,000,000 downwards in the figure). In this case the radio signals (e.g., the TV channels) are trans- ported in a coaxial cable medium. What a CATV operator might do is to use the band from 50 MHz to 1 GHz for transmission outwards from the headend for TV channels and "other services" and the band from about 5 MHz to 50 MHz to be employed from the user back to the headend. This band will transport the other services in a full duplex mode. These other services include POTS (plain old telephone service) and data. In this chapter, we will describe conventional CATV, and the concept of supertrunks including HFC (hybrid fiber-coax