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Main article: "Hybrid fibre-coaxial

Modern cable systems are large, with a single network and headend often serving an entire "metropolitan area. Most systems use "hybrid fiber-coaxial (HFC) distribution; this means the trunklines that carry the signal from the headend to local neighborhoods are "optical fiber to provide greater bandwidth and also extra capacity for future expansion. At the headend, the "radio frequency electrical signal carrying all the channels is modulated on a light beam and sent through the fiber. The fiber trunkline goes to several distribution hubs, from which multiple fibers fan out to carry the signal to boxes called optical nodes in local communities. At the optical node, the light beam from the fiber is translated back to an electrical signal and carried by "coaxial cable distribution lines on utility poles, from which cables branch out to subscriber residences.

Deployments by continent[edit]

Cable television by region

Cable television is mostly available in "North America, "Europe, "Australia and "East Asia, and less so in "South America and the "Middle East. Cable television has had little success in "Africa, as it is not cost-effective to lay cables in sparsely populated areas. So-called "wireless cable" or "microwave-based systems are used instead.

Other cable-based services[edit]

Coaxial cables are capable of bi-directional carriage of signals as well as the transmission of large amounts of "data. Cable television signals use only a portion of the bandwidth available over coaxial lines. This leaves plenty of space available for other digital services such as "cable internet, "cable telephony and wireless services, using both unlicensed and licensed spectrum. "Broadband internet access is achieved over coaxial cable by using "cable modems to convert the "network data into a type of digital signal that can be transferred over coaxial cable. One problem with some cable systems is the older amplifiers placed along the cable routes are unidirectional thus in order to allow for uploading of data the customer would need to use an analog telephone modem to provide for the upstream connection. This limited the upstream speed to 31.2k and prevented the always-on convenience broadband internet typically provides. Many large cable systems have upgraded or are upgrading their equipment to allow for bi-directional signals, thus allowing for greater upload speed and always-on convenience, though these upgrades are expensive.

In "North America, "Australia and "Europe, many cable operators have already introduced "cable telephone service, which operates just like existing fixed line operators. This service involves installing a special telephone interface at the customer's premises that converts the analog signals from the customer's in-home wiring into a digital signal, which is then sent on the "local loop (replacing the analog "last mile, or "plain old telephone service (POTS)) to the company's switching center, where it is connected to the public switched telephone network ("PSTN). The biggest obstacle to cable telephone service is the need for nearly 100% reliable service for emergency calls. One of the standards available for digital cable telephony, "PacketCable, seems to be the most promising and able to work with the "quality of service (QOS) demands of traditional analog "plain old telephone service (POTS) service. The biggest advantage to digital cable telephone service is similar to the advantage of digital cable, namely that data can be compressed, resulting in much less bandwidth used than a dedicated analog circuit-switched service. Other advantages include better voice quality and integration to a "Voice over Internet Protocol (VoIP) network providing cheap or unlimited nationwide and international calling. In many cases, digital cable telephone service is separate from "cable modem service being offered by many cable companies and does not rely on "Internet Protocol (IP) traffic or the Internet.

Traditional cable television providers and traditional telecommunication companies increasingly compete in providing voice, video and data services to residences. The combination of television, telephone and Internet access is commonly called ""triple play", regardless of whether CATV or "telcos offer it.

See also[edit]


  1. ^ "ClearQAM – What It Is And Why It Matters". Retrieved 19 June 2015. 

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