Cable television systems provide video and data services through a system of high bandwidth coaxial cables and fibers. The cable network includes a head-end amplifier that combines the broadcast and data signals for transmission to the subscribers. High-speed Internet access is obtained by including a cable modem termination system (CMTS) function within the head-end that connects to a 10/100Mbps Ethernet router. The head-end is connected to fiber or coax trunks that carry the signals into the neighborhoods where they are tapped off to provide service to the residence.

Earlier cable TV systems provided only one-way broadcast type services such as standard and premium channel television. Upgrading these earlier systems to support the two-way communications necessary to offer Internet access, pay-per-view, voice and video-on-demand services requires large capital investments. Many cable TV carriers have merged with large telecommunications companies in order to take advantage of the enormous market potential that exists. Cable TV systems can deliver high-speed Internet access at costs that are far below that of digital subscriber line (DSL).

Figure 9.16 shows a typical cable television network. This diagram shows that cable television systems can be simple one-way video distribution systems to advanced two-way high-speed digital networks. The head-end is the initial distribution center for a cable television (CATV) system. The head end is where incoming video and television signal sources (e.g., video tape, satellites, local studios) are received, amplified, and modulated onto TV carrier channels for transmission on the CATV cabling system. The cable distribution...