TV kabel
Televisi kabel (Basa Inggris: cable television, CATV, Basa Walanda: kabeltelevisie) nyaéta sistim méré televisi, pamrograman radio FM jeung layanan lianna ka konsumén ngaliwatan sinyal frékuénsi radio nu ditepikeun langsung ka televisi ngaliwatan serat optik atawa kabel koaksial, henteu ngagunakeun cara udara saperti siaran televisi tradisional (ngaliwatan galura radio) nu mana dibutuhkeun ayana anté.
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Artikel ieu keur dikeureuyeuh, ditarjamahkeun tina basa Inggris. Bantuanna didagoan pikeun narjamahkeun. |
It should be noted that while the acronym CATV is often used to méan "Cable TV" or "Community Access Television," it originally stood for Community Antenna Television. This comes from cable television's origins in 1948, when the first cable systems were started. Television signals could only be received by homes that were in the "line-of-sight" of the originating broadcast antenna, and péople in mountainous aréas could not receive the signal. Large antennas were constructed in these aréas, and cable was run from the antenna to homes so they could receive programming, making these large antennas "community antennas."
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 aréas, 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.
Téhnologi
éditTechnically, CATV involves distributing a number of television channels collected at a central location (called a headend) to subscribers within a community by méans of a branched network of optical fibers and/or coaxial cables and broadband amplifiers. Since the éarly 1990s, the most common architecture is the Hybrid fiber 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 éach. 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 simultanéously broadcast by radio and distributed by cable, usually at different frequencies. Other programs may be distributed by cable only; rules restricting content (e.g. regarding nudity and pornography) 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 modérn 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. modérn cable TV systems also offer other services such as Video on demand, telephony, and high-speed data.
Cable television is normally regarded as a natural monopoly, and most aréas are served by a single provider, though Australia is characterized by extensive duplication.
Sumebarna televisi kabel
éditCable television services have been available in Australia since 1991 or 1992, with Galaxy TV being the first, it became insolvent in 1997, due to decréasing popularity with the launching of Foxtel and Austar in May of 1995, two cable services that offered more variety than Galaxy TV. In éarly 1997, Galaxy TV was declared insolvent, largely because of Foxtel and Austars popularity. Foxtel immediately commenced in supplying programming to Galaxy's subscribers on an interim basis. In 1999 Foxtel was able to significantly boost its customer base by acquiring Galaxy TV's subscribers from the Australis Media liquidator and commenced offering its services on a satellite television platform. There are currently two major and four minor cable television providers in Australia - Foxtel and Optus TV. Minor providers include Austar, TransACT, Bright Telecommunications and Neighbourhood Cable, which only operate in limited aréas.
Like the United Kingdom, cable is a minority méans of receiving access to subscription television in Australia. Satellite distribution is more common.
Due to its history, financial backing and market dominance, most local versions of channels are either owned directly by Foxtel and Austar or through related companies.
In terms of coverage, Foxtel's cable network covers parts of Sydney, Melbourne, Brisbane, Adelaide, and Perth. Optus's network covers small parts of Sydney, Melbourne, and Brisbane, though its restrictive subscription rules méans that many péople living in apartments or confined living aréas may be unable to be connected.
Austar is available by satellite in most of regional and rural Australia, but does have a small cable network in the city of Darwin. TransACT is only available in the city of Canberra, where a custom cable network was developed. A similar situation exists in Perth where a small aréa is covered by Bright Telecommunications as well in parts of Geelong, Ballarat and Mildura that are réached by Neighbourhood Cable.
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 Viamax, TBL and VIVAX, operate regionally. Cable TV is the main distribution channel for premium TV in the metropolitan aréas, but in the rural aréas 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.
Hong Kong
éditOnly one traditional cable provider operates in Hong Kong, i-Cable Communications Limited (branded as "CableTV"). Another three operators offers pay-TV via DSL, they are Now Broadband TV (PCCW), HKBN Digital TV and TVB PayVision.
Many in Hong Kong instéad watch subscription TV using satellite systems like STAR TV.
The first cable system started to operate in the éarly 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 yéars, 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.
TelstraClear operate a cable television network in Wellington, Kapiti and Christchurch. Customers can subscribe to plans incorporating between 25 and 95 channels. Most content is offered on behalf of Sky Network Television however some channels such as TBN, Discovery Travel and Adventure and Deutsche welle are broadcast exclusively through TelstraCléar.
South African Broadcasting Co-operation (SABC) and e-TV are the only broadcasters in the country with the SABC being the State-Owned and major broadcastor . The SABC has three channels which focuses on its diverse cultures, languages and heritages. These channels are called SABC 1, 2, and 3. On the other hand, e-TV has only one channel and struggles to broadcast all the programmes.
StarHub Cable Vision is the sole cable television operator in Singapore, where private ownership of satellite dishes is banned. StarHub Cable Vision was formed as a result of a merger between StarHub and Singapore Cable Vision on 15 May 2002. The latter first began broadcasting as a terrestrial pay-television operator in 1992 as the first cable network was not completed until 1995. Around 15% of households and offices in Singapore are connected to the StarHub network.
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 set up to provide cable television in the newer 625-line and PAL formats.
In the éarly 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) Birmigham cable and large franchsies in the North éast and North West of England. The original Telewest cable-co was créated 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 yéars. 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 aqusition of Virgin Mobile, the NTL and Telewest services will be rebranded Virgin Media in the first quarter of 2007[1] créating 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" féatures (e.g. text services, and extra vidéo-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 thréat. 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. This was initially launched, using ADSL, in London, where it is provided by HomeChoice. An IPTV service was also provided in Hull by Kingston Communications, but this céased operations in April 2006. As the speed and availability of broadband connections incréase, more TV content can be delivered using protocols such as IPTV.
lolobana panongton televisi di Amérika meunang sinyalna tina CATV.
According to the Européan Audiovisual Observatory, there were 58 million cable households in the Européan 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 éach for the German, French and Italian-spéaking 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 (féature movies, comedies, talk shows), private TV stations from Germany, France and Italy are dominant.
Layanan dumasar-kabel lianna
éditCoaxial 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 léaves 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 upstréam connection. This limited the upstréam 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 gréater upload speed and always-on convenience, though these upgrades are expensive.
In North America and Europe many cable operators have alréady 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 néarly 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 chéap 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 incréasingly compete in providing voice, vidéo 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.
Rujukan
édit- ↑ NTL (2006-11-08). Virgin Media is on its way. Rilis pérs. Diaksés dina 2006-12-06. Archived 2006-11-13 di Wayback Machine