TV - Cable- Inglês

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Cable television is a system of providing television to consumers via radio frequency signals transmitted to televisions through fixed optical fibers or coaxial cables as opposed to the over-the-air method used in traditional television broadcasting (via radio waves) in which a television antenna is required. FM radio programming, high-speed Internet, telephony and similar non television services may also be provided.

The abbreviation CATV is often used to mean "Cable TV". It originally stood for Community Antenna Television, from cable television's origins in 1948: in areas where over-the-air reception was limited by mountainous terrain, large "community antennas" were constructed, and cable was run from them to individual homes.

It is most commonplace in North America, Europe, Australia and East Asia, though it is present in many other countries, mainly in South America and the Middle East. Cable TV has had little success in Africa, as it is not cost-effective to lay cables in sparsely populated areas, and although so-called "wireless cable" or microwave-based systems are used, "direct-to-home" satellite television is far more popular, especially in South Africa.


Technically, CATV involves distributing a number of television channels collected at a central location (called a headend) to subscribers within a community by means of a branched network of optical fibers and/or coaxial cables and broadband amplifiers. Since the early 1990s, the most common architecture is the Hybrid fibre-coaxial network.

As in the case of radio broadcasting, the use of different frequencies allows many channels to be distributed through the same cable, without separate wires for each. A Set-top box or the tuner of the TV, VCR or radio selects one channel from this mixed signal.

The same program is often simultaneously broadcast by radio waves and distributed by cable. Other programs may be distributed by cable only; rules restricting content (e.g. regarding nudity and profanity) are often more relaxed for cable than for over-the-air TV.

Traditional cable TV systems worked strictly by way of analog signals (i.e. using standard radio waves) but many modern cable TV systems also employ the use of digital cable technology, which uses compressed digital signals, allowing them to provide many more channels than they could with analog alone. Modern cable TV systems also offer other services such as Video on demand, telephony, and high-speed data.

Cable television service has been regarded as a natural monopoly by many, and most areas are still served by a single provider, though Australia is characterized by extensive duplicationPredefinição:Ambiguous link. In the United States a monopoly on cable television has historically been enforced by local governments. In order to provide service to individual homes, a cable provider must place its cable wiring along and across local streets. To do so the provider must get permission from the local government(s) that own these streets. This permission comes in the form of a document called a franchise agreement. Most of local government(s) chose to grant permission to only one company. Changes in the law in the past few years have forced local governments to grant permission to other companies to provide service.

Cable television deployments


Cable television is distributed in Brazil by various companies. Two of them, NET and TVA, serve the majority of the country, and lesser companies, such as WayTV, TBL and VIVAX, operate regionally. Cable TV is the main distribution channel for premium TV in the metropolitan areas, but in the rural areas satellite television is used more frequently because of the limited availability of cables infrastructure. Free broadcast television is still the main distribution channel in the whole country, however.


Cable television in Canada began in 1952 with community antenna connections in Vancouver and London; which city is first is not clear. Initially, the systems brought American stations to viewers in Canada who had no Canadian stations to watch; broadcast television, though begun late in 1952 in Toronto and Montreal, did not reach a majority of cities until 1954.

In time, cable television was widely established to carry available Canadian stations as well as import American stations, which constituted the vast majority of signals on systems (usually only one or two Canadian stations, while some systems had duplicate or even triplicate coverage of American networks). During the 1970s, a growing number of Canadian stations pushed American channels off the systems, forcing several to expand beyond the original 12-channel system configurations. At the same time, the advent of fibre-optic technology enabled companies to extend their systems to nearby towns and villages that by themselves were not viable cable television markets.

Specialty television channels available only on cable began to be established in 1983, and systems continued to expand and upgrade their channel capacity, notably by deploying fibre-optics to carry signals in digital format as far as neighbourhoods before converting to coaxial cable for the final run to the customer premises. Two-way capabilities were introduced, and larger systems were able to use "addressable" descramblers to offer pay-TV and different tiers of channels.

Cable television began to face serious competition from DTH satellite services in the late 1990s. Telephone companies and cable television companies have since been permitted, in most parts of Canada, to compete to provide services originally provided by the other. Cable television services are not the prime providers of broadband Internet in Canada, but they are a very strong competitor for the service.

During the early 1970s, Canadian television stations obtained regulatory rulings that required cable television operators to substitute their signals for distant (usually American) stations carrying the same television program at the same time. This annoyed Canadian viewers because Canadian broadcasters carried more commercial advertising, necessarily requiring the cutting of scenes from the program, Predefinição:Fact but it protected the stations' advertising sales.

Many systems were originally locally owned, and many large cities had several providers each covering specific sections of a city; a long series of consolidations and acquisitions rapidly brought most major cities' systems under the ownership of a small number of large companies.

Presently, cable is provided to most cities and towns, depending on the region, by companies such as Rogers Communications, Shaw Communications, Vidéotron, Cogeco, Persona, Cable Axion, Dery Telecom, and EastLink. Most of these "first-generation" cable companies do not compete with each other, as the CRTC has traditionally licensed only one cable provider per market. Even in markets where more than one distributor has been licensed, each has an exclusive territory within the market. However, most telephone companies such as Bell Canada, Telus, Aliant, MTS and SaskTel have recently secured cable television distribution licences in their own territories, several of which are already in use.


The first cable system started to operate in the early Sixties in Monterrey, as a CATV service (an antenna at the top of the Loma Larga, which could get TV signals from South Texas). Most of the other major cities didn't develop cable systems until the late Eighties, due to government censorship. By 1989 the industry had had a major impulse with the founding of Multivisión—a MMDS system who started to develop its own channels in Spanish—and the later development of companies such as Cablemas and Megacable.

Over the past few years, many US networks have started to develop content for the Latin American market, such as CNN en Español, MTV, Cartoon Network, Disney Channel, and others. The country also has a DTH service called SKY (Televisa & News Corp. owned). Recently DirecTV merged with Sky. The dominant company nowadays is Megacable and Grupo HEVI.

United Kingdom

In the UK Cable Television had its origins in 1938, when the first Community Antenna TV systems were set up in towns including Bristol and Hull, for homes which couldn't receive transmissions over the air; however these signals were on the 405-line system. In the 1960s Rediffusion Vision was setup to provide cable television in the newer 625-line and PAL formats.

In the early 1980s Rediffusion Vision supplemented its service with other channels including The Music Box, Mirrorvision, Lifesyle Screensport, Sky Channel and TEN. The service was renamed to Rediffusion Cablevision.

In the United Kingdom, the current generation of cable television began in the late 1980s with the issue of franchises to many local operators. These small operations proved uneconomic and there has been a continuing process of consolidation and re-financing.

By 2000 the two principal cable operators were NTL and Telewest. NTL's cable service was originally known as CableTel and grew rapidly through the acquisition of, among others, ComTel (which itself had bought Telecential), Comcast, Diamond Cable and finally, in 1999, the residential and small business operations of Cable & Wireless. Telewest acquired local cable operators including Eurobell (Plymouth and Essex) Cable London (North franchise) Birmingham cable and large franchises in the North East and North West of England. The original Telewest cable-co was created after mergers of United Artists and General Cable in the mid 90's. In 2005 it was announced that NTL and Telewest would merge, after a period of co-operation in the preceding few years. This merger was completed on 3 March 2006 with the company being named ntl Incorporated. For the time being the two brand names and services are still being marketed separately. However, following NTL's acquisition of Virgin Mobile, the NTL and Telewest services were rebranded Virgin Media on 2007-02-08 creating a single cable operator covering more than 95% of the UK cable market.

There are a small number of other surviving cable television companies in the UK outside of NTL including Kingston Communications (East Riding of Yorkshire) and WightCable (Isle of Wight, Ayrshire, Carlisle and Lancashire).

Cable TV faces intense competition from BSkyB's Sky Digital satellite television service. Most channels are carried on both platforms. However, cable often lacks "interactive" features (e.g. text services, and extra video-screens), especially on BSkyB owned channels, and the satellite platform lacks services requiring high degrees of two-way communication, such as true video on demand.

However, subscription-funded digital terrestrial television proved less of a competitive threat. The first system, ITV Digital, went into liquidation in 2002. Top Up TV later replaced it, however this service is shrinking as the DVB-T multiplex owners are finding FTA broadcasting more profitable.

Another potential source of competition in the future will be TV over broadband internet connections; this is known as IPTV. Some IPTV services are currently available in London, while services operated in Hull ceased in April 2006. As the speed and availability of broadband connections increase, more TV content can be delivered using protocols such as IPTV. However, its impact on the market is yet to be measured, as is consumer attitude toward watching TV programmes on computers instead of television sets. BT (The UK's phone company) and the end of 2006 started offering BT Vision which is basically TV delivered over a broadband connection and displayed on a Television. This service was started due to high broadband speeds in the UK. There are plans for a 100MB/sec to be offered.

United States

Cable television in the United States is a common form of television delivery, generally by subscription. Cable television first became available in the United States in 1948, with subscription services in 1949. Recent data shows that 84.8% of all American homes have access to cable television.

During the television licensing freeze of 1948-1952, the demand for television increased. Since new television licenses were not being issued, the only way the demand was met was by Community Antenna Television. The first American CATV System is believed to have been developed in 1948 by Robert Tarlton. He had interest in an appliance store that began to carry televisions. A major problem in selling televisions in Lansford, Pennsylvania was that the stations which were available were received very poorly due to Lansford's location in a narrow valley roughly 100 miles from New York City and Philadelphia, PA. Tarlton and several other prominent town businessmen built an antenna on the top of a nearby mountain and strung a wire from it to Tarlton's shop and his house. The businessmen, including the founder of Jerrold Electronics Corporation, Milton Shapp, also developed a basic infrastructure (including the first cable signal amplifier, developed by Jerrold) to deploy and distribute the cable wire to homes in the community for a fee. In 1949 the world's first cable company was incorporated as The Panther Valley Cable Company, which eventually became Blue Ridge Cable Television.

Another system was built less than 20 miles away in the nearby town of Mahanoy City, PA at roughly the same time with very little or no common knowledge between the two systems. The Mahanoy system was founded by John Walson. The Mahanoy system eventually became Service Electric Cable Television.

Both Panther Valley and Mahanoy were originally three-channel systems and were upgraded to five. Other systems were built: some conceived the idea independently, others didn't, and others laid claim to the title of first.

In 1969 the FCC issued rules requiring all CATV systems with over 3500 subscribers to have facilities for local origination of programming by April 1, 1971. The date was later suspended. In 1972, Dean Burch steered the FCC into a new area of regulation. It lifted its restrictions on CATV in large cities, but now put the burden of more local programming on CATV operators. In 1976, the FCC used its rule making power to require that new systems now had to have 20 channels, and that cable providers with systems of 3500 subscribers or more had to provide PEG (public, education, and government access) channel capacity, and facilities and equipment necessary to use this capacity.


According to the European Audiovisual Observatory, there were 58 million cable households in the European Union as of 31 December 2004, i.e. a rate of penetration of 32 % of the television households. 5.7 millions were connected to digital networks.


In Switzerland, virtually all households have cable TV. Ironically, despite this good coverage, Switzerland has only a few public TV stations (two each for the German, French and Italian-speaking parts of the country); additionally, there is now only one upstart commercial network with coverage comparable to these state-run channels. To watch news or political information, Swiss channels are preferred, but in the entertainment sector (feature movies, comedies, talk shows), private TV stations from Germany, France and Italy are dominant.

Other cable-based services

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 broadband internet and cable telephony.

Broadband internet 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 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 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 POTS) to the company's switching center, where it is connected to the 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 demands of traditional analog POTS service. The biggest advantage to digital cable telephone service is similar to the advantage of digital cable TV, 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 VoIP network providing cheap or unlimited nationwide and international calling. Note that in many cases, digital cable telephone service is separate from cable modem service being offered by many cable companies and does not rely on IP traffic or the Internet.

Beginning in 2004 in the United States, the traditional cable television providers and traditional telecommunication companies increasingly compete in providing voice, video and data services to residences. The combination of TV, telephony and Internet access is commonly called triple play regardless of whether CATV or telcos offer it.