HOME
TheInfoList



Cable television is a system of delivering
television Television (TV), sometimes shortened to tele or telly, is a telecommunication medium used for transmitting moving images in monochrome (black and white), or in color, and in two or three dimensions and sound. The term can refer to a televisi ...

television
programming to consumers via
radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the upper ...
(RF) signals transmitted through
coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric (insulating material); many coaxial cables also have a protec ...
s, or in more recent systems, light pulses through
fibre-optic cable optical fiber cable with a clear jacket. These cables are used mainly for digital audio connections between devices. A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable, but containing one or ...
s. This contrasts with
broadcast television Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting standards for the transmission and reception of terrestrial television signals. There were three main analog television system ...
(also known as terrestrial television), in which the television signal is transmitted over-the-air by
radio wave Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz (Hz). At 300 GHz, th ...
s and received by a
television antenna A television antenna (TV aerial) is an antenna specifically designed for use with a television receiver (TV) to receive over-the-air broadcast television signals from a television station. Terrestrial television is broadcast on frequencies fro ...
attached to the television; or
satellite television Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna commonl ...
, in which the television signal is transmitted over-the-air by
radio wave Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz (Hz). At 300 GHz, th ...
s from a
communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Com ...
orbiting the Earth, and received by a
satellite dish satellite dish. A satellite dish is a dish-shaped type of parabolic antenna designed to receive or transmit information by radio waves to or from a communication satellite. The term most commonly means a dish which receives direct-broadcast sat ...
antenna on the roof.
FM radio in Henderson, Nevada and broadcasts at a frequency of 95.5 MHz. FM broadcasting is a method of radio broadcasting using frequency modulation (FM). Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide hig ...
programming,
high-speed Internet Internet access is the ability of individuals and organizations to connect to the Internet using computer terminals, computers, and other devices; and to access services such as email and the World Wide Web. Internet access is sold by Internet ser ...
, telephone services, and similar non-television services may also be provided through these cables.
Analog television Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog s ...
was standard in the 20th century, but since the 2000s, cable systems have been upgraded to
digital cable Digital cable is the distribution of cable television using digital video compression for distribution. The technology was developed by General Instrument, which was succeeded by Motorola and subsequently by ARRIS Group. Cable companies converte ...
operation. A "cable channel" (sometimes known as a "cable network") is a television network available via cable television. When available through
satellite television Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna commonl ...
, including direct broadcast satellite providers such as
DirecTV DirecTV (trademarked as DIRECTV) is an American direct broadcast satellite service provider based in El Segundo, California, and is a subsidiary of AT&T. Its satellite service, launched on June 17, 1994, transmits digital satellite television a ...
,
Dish Network DISH Network Corporation is an American television provider based in Englewood, Colorado. It is the owner of the direct-broadcast satellite provider DISH, also still commonly known as DISH Network, and the over-the-top IPTV service Sling TV. DISH ...
and
Sky The sky (also sometimes called celestial dome) is everything that lies above the surface of the Earth, including the atmosphere and outer space. In the field of astronomy, the sky is also called the celestial sphere. This is an abstract sphere ...
, as well as via
IPTV Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded media, ...
providers such as
Verizon FIOS Verizon Fios, also marketed as Fios by Verizon, is a bundled Internet access, telephone, and television service that operates over a fiber-optic communications network with over 5 million customers in nine U.S. states. The name, Fios, is an acron ...
and
AT&T U-verse AT&T U-verse, commonly called U-verse, is an AT&T brand of triple-play telecommunications services, although the brand is now only used in reference to the IPTV service. Launched on June 26, 2006, U-verse included broadband Internet (now AT&T Inter ...
, this is referred to as a "satellite channel". Alternative terms include "non-broadcast channel" or "programming service", the latter being mainly used in legal contexts. Examples of cable/satellite channels/cable networks available in many countries are
HBO Home Box Office (HBO) is an American pay television network owned by WarnerMedia Studios & Networks and the flagship property of parent subsidiary Home Box Office, Inc. Maintaining a general entertainment format, programming featured on the ne ...
,
Cinemax Cinemax (Cinemax India Ltd.) is an Indian Cinema Chain with 138 screens across 39 properties in India including Ahmedabad, Bangalore, Hyderabad, Kochi, Mumbai, Pune, Kolkata, Kanpur, Bhopal and Nashik. It was previously owned by the Kanakia grou ...
,
MTV MTV (originally an initialism of Music Television) is an American cable channel that launched on August 1, 1981. Based in New York City, it serves as the flagship property of the ViacomCBS Domestic Media Networks division of ViacomCBS. Prior t ...
,
Cartoon Network Cartoon Network (often shortened to CN) is an American cable television channel owned by the Kids, Young Adults and Classics division of Warner Bros. Entertainment, itself a subsidiary of AT&T's WarnerMedia through its Studios and Networks Gro ...

Cartoon Network
,
AXN AXN is a pay television channel owned by Sony Pictures Television, which was first launched on June 22, 1997. Local versions have since been launched in several parts of the world, including Europe, Japan, Asia, and Latin America. Funded thro ...
,
E! E! (an initialism for Entertainment Television) is an American basic cable channel which primarily focuses on pop culture, celebrity focused reality shows, and movies, owned by the NBCUniversal Television and Streaming division of NBCUniversal, ...
, FX,
Discovery Channel Discovery Channel (known as The Discovery Channel from 1985 to 1995, and often referred to as simply Discovery) is an American multinational pay television network and flagship channel owned by Discovery, Inc., a publicly traded company run by ...
,
Canal+ Canals are waterways channels, or artificial waterways, for water conveyance, or to service water transport vehicles. They may also help with irrigation. It can be thought of as an artificial version of a river. Canals carry free surface fl ...

Canal+
,
Eurosport Eurosport is a pan-European television sports network and a subsidiary of Discovery. Eurosport owns a wide range of rights across many sports but generally does not bid for premium priced rights such as those to major football leagues. However, ...
,
NBC Sports NBC Sports is an American programming division of the broadcast network NBC, owned and operated by NBC Sports Group division of NBCUniversal and subsidiary of Comcast, that is responsible for sports broadcasts on the network, and its dedicated na ...
,
Fox Sports Fox Sports is the brand name for a number of sports channels, broadcast divisions, programming, and other media around the world. The name originates from the Fox Broadcasting Company in the United States, which in turn derives its name from Fox ...
, PBS Sports,
Disney Channel Disney Channel (originally called The Disney Channel from 1983 to 1997 and commonly shortened to Disney from 1997 to 2002) is an American pay television channel that serves as the flagship property of owner Disney Branded Television, a unit of ...
,
Nickelodeon Nickelodeon (often shortened to Nick) is an American pay television channel which was first tested on December 1, 1977, until it eventually launched on April 1, 1979 as the first cable channel for children. It is owned by ViacomCBS through it ...
,
CNN International CNN International (CNNI, on-air branding simply as CNN) is an international television channel that is operated by CNN. CNN International carries news-related programming worldwide; it cooperates with parent network CNN's national and internatio ...
, PSN and
ESPN ESPN (originally an initialism for Entertainment and Sports Programming Network) is an American multinational basic cable sports channel owned by ESPN Inc., owned jointly by The Walt Disney Company (80%) and Hearst Communications (20%). The com ...

ESPN
. The abbreviation CATV is often used for cable television. It originally stood for ''Community Access Television'' or ''Community Antenna Television'', from cable television's origins in 1948. In areas where over-the-air TV reception was limited by distance from transmitters or mountainous terrain, large "community antennas" were constructed, and cable was run from them to individual homes. In 1968 6.4% of Americans had cable television. The number increased to 7.5% in 1978. By 1988 52.8% of all households were using cable. The number further increased to 62.4% in 1994.


Distribution

To receive cable television at a given location, cable distribution lines must be available on the local utility poles or underground utility lines.
Coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric (insulating material); many coaxial cables also have a protec ...
brings the signal to the customer's building through a
service drop In electric power distribution, a service drop is an overhead electrical line running from a utility pole, to a customer's building or other premises. It is the point where electric utilities provide power to their customers.Carson Dunlop "Elect ...

service drop
, an overhead or underground cable. If the subscriber's building does not have a cable service drop, the cable company will install one. The standard cable used in the U.S. is
RG-6 RG-6/U is a common type of coaxial cable used in a wide variety of residential and commercial applications. An RG-6/U coaxial cable has a characteristic impedance of 75 ohms. The term, ''RG-6'', is generic and is applied to a wide variety of c ...
, which has a 75 ohm impedance, and connects with a type
F connector The F connector (also F-type connector) is a coaxial RF connector commonly used for "over the air" terrestrial television, cable television and universally for satellite television and cable modems, usually with RG-6/U cable or with RG-59/U cable. ...
. The cable company's portion of the wiring usually ends at a distribution box on the building exterior, and built-in cable wiring in the walls usually distributes the signal to jacks in different rooms to which televisions are connected. Multiple cables to different rooms are split off the incoming cable with a small device called a splitter. There are two standards for cable television; older analog cable, and newer
digital cable Digital cable is the distribution of cable television using digital video compression for distribution. The technology was developed by General Instrument, which was succeeded by Motorola and subsequently by ARRIS Group. Cable companies converte ...
which can carry data signals used by
digital television Digital television (DTV) is the transmission of television audiovisual signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innova ...
receivers such as
high-definition television High-definition television (HD) describes a television system providing an image resolution of substantially higher resolution than the previous generation of technologies. The term has been used since 1936, but in modern times refers to the genera ...
(HDTV) equipment. All cable companies in the United States have switched to or are in the course of switching to digital cable television since it was first introduced in the late 1990s. Most cable companies require a set-top box (
cable converter box 250px, Pace Micro Technology DC757X HD cable box A cable converter box or television converter box is an electronic tuning device that transposes/converts channels from a cable television service to an analog RF signal on a single channel, usually ...
) or a slot on one's TV set for conditional access module cards to view their cable channels, even on newer televisions with digital cable
QAM Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message signals ...
tuners, because most digital cable channels are now encrypted, or "scrambled", to reduce cable service theft. A cable from the jack in the wall is attached to the input of the box, and an output cable from the box is attached to the television, usually the RF-IN or composite input on older TVs. Since the set-top box only decodes the single channel that is being watched, each television in the house requires a separate box. Some unencrypted channels, usually traditional over-the-air broadcast networks, can be displayed without a receiver box. The cable company will provide set-top boxes based on the level of service a customer purchases, from basic set-top boxes with a
standard definition Standard-definition television (SDTV, SD, often shortened to standard definition) is a television system which uses a resolution that is not considered to be either high or enhanced definition. SDTV and high-definition television (HDTV) are th ...
picture connected through the standard coaxial connection on the TV, to high-definition wireless
digital video recorder A digital video recorder (DVR) is an electronic device that records video in a digital format to a disk drive, USB flash drive, SD memory card, SSD or other local or networked mass storage device. The term includes set-top boxes with direct to di ...
(DVR) receivers connected via
HDMI HDMI (High-Definition Multimedia Interface) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, to ...
or
component Component may refer to: In engineering, science, and technology Generic systems *System components, an entity with discrete structure, such as an assembly or software module, within a system considered at a particular level of analysis *Lumped ele ...
. Older
analog television Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog s ...
sets are "cable ready" and can receive the old analog cable without a set-top box. To receive digital cable channels on an
analog television Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog s ...
set, even unencrypted ones, requires a different type of box, a
digital television adapter A digital TV converter box A digital television adapter (DTA), commonly known as a converter box or decoder box, is a television tuner that receives a digital television (DTV) transmission, and converts the digital signal into an analog signal that ...
supplied by the cable company or purchased by the subscriber. Another new distribution method that takes advantage of the low cost high quality DVB distribution to residential areas, uses
TV gatewayA TV gateway (also called network TV tuner) is a television headend to a network UPnP router that receives live digital video broadcast (DVB) MPEG transport streams (channels) from terrestrial aerials, satellite dishes, or cable feeds and converts th ...
s to convert the
DVB-C DVB-C stands for "Digital Video Broadcasting - Cable" and it is the DVB European consortium standard for the broadcast transmission of digital television over cable. This system transmits an MPEG-2 or MPEG-4 family digital audio/digital video stre ...
,
DVB-C2 DVB-C stands for "Digital Video Broadcasting - Cable" and it is the DVB European consortium standard for the broadcast transmission of digital television over cable. This system transmits an MPEG-2 or MPEG-4 family digital audio/digital video stre ...
stream to IP for distribution of TV over IP network in the home. Many cable companies offer internet access through
DOCSIS Data Over Cable Service Interface Specification is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable television operators to ...
.https://www.cisco.com/c/dam/en/us/solutions/collateral/service-provider/cable-access-solutions/cable-ebook.pdf


Principle of operation

In the most common system, multiple television channels (as many as 500, although this varies depending on the provider's available channel capacity) are distributed to subscriber residences through a
coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric (insulating material); many coaxial cables also have a protec ...
, which comes from a trunkline supported on
utility pole#REDIRECT Utility pole#REDIRECT Utility pole {{R from other capitalisation ...
{{R from other capitalisation ...
s originating at the cable company's local distribution facility, called the " headend". Many channels can be transmitted through one coaxial cable by a technique called
frequency division multiplexing Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angular frequency. Frequency is measured in hertz (Hz) which is e ...
. At the headend, each television channel is translated to a different
frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angular frequency. Frequency is measured in hertz (Hz) which is e ...
. By giving each channel a different frequency "slot" on the cable, the separate television signals do not interfere with each other. At an
outdoor cable box
outdoor cable box
on the subscriber's residence, the company's service drop cable is connected to cables distributing the signal to different rooms in the building. At each television, the subscriber's television or a set-top box provided by the cable company translates the desired channel back to its original frequency (
baseband Baseband is a signal that has a near-zero frequency range, i.e. a spectral magnitude that is nonzero only for frequencies in the vicinity of the origin (termed ''f'' = 0) and negligible elsewhere. In telecommunications and signal processing, baseb ...
), and it is displayed onscreen. Due to widespread cable theft in earlier analog systems, the signals are typically
encrypted In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can deciph ...
on modern digital cable systems, and the set-top box must be activated by an
activation code Activation, in chemistry and biology, is the process whereby something is prepared or excited for a subsequent reaction. Chemistry In chemistry, "activation" refers to the reversible transition of a molecule into a nearly identical chemical or ph ...
sent by the cable company before it will function, which is only sent after the subscriber signs up. If the subscriber fails to pay their bill, the cable company can send a signal to deactivate the subscriber's box, preventing reception. There are also usually "
upstream Upstream may refer to: * Upstream (bioprocess) * ''Upstream'' (film), a 1927 film by John Ford * Upstream (mobile marketing), a company * Upstream (networking) * ''Upstream'' (newspaper), a newspaper covering the oil and gas industry * Upstream (pe ...
" channels on the cable to send data from the customer box to the cable headend, for advanced features such as requesting
pay-per-view Pay-per-view (PPV) is a type of pay television or webcast service by which a viewer can purchase events to view via private telecast. The broadcaster shows the event at the same time to everyone ordering it. Events can be purchased through a multic ...
shows or movies,
cable internet access In telecommunications, cable Internet access, shortened to cable Internet, is a form of broadband Internet access which uses the same infrastructure as a cable television. Like digital subscriber line and fiber to the premises services, cable Inter ...
, and cable telephone service. The "
downstream Downstream may refer to: * Downstream (bioprocess) * Downstream (manufacturing) * Downstream (networking) * Downstream (software development) * Downstream (petroleum industry) * Upstream and downstream (DNA), determining relative positions on DNA * ...
" channels occupy a band of
frequencies Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angular frequency. Frequency is measured in hertz (Hz) which is e ...
from approximately 50 MHz to 1 GHz, while the "
upstream Upstream may refer to: * Upstream (bioprocess) * ''Upstream'' (film), a 1927 film by John Ford * Upstream (mobile marketing), a company * Upstream (networking) * ''Upstream'' (newspaper), a newspaper covering the oil and gas industry * Upstream (pe ...
" channels occupy frequencies of 5 to 42 MHz. Subscribers pay with a monthly fee. Subscribers can choose from several levels of service, with "premium" packages including more channels but costing a higher rate. At the local headend, the feed signals from the individual television channels are received by dish antennas from
communication satellite Communication (from Latin ''communicare'', meaning "to share") is the act of developing meaning among entities or groups through the use of sufficiently mutually understood signs, symbols, and semiotic conventions. The main elements inherent to ...
s. Additional local channels, such as local
broadcast television Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting standards for the transmission and reception of terrestrial television signals. There were three main analog television system ...
stations, educational channels from local colleges, and community access channels devoted to local governments ( PEG channels) are usually included on the cable service.
Commercial Commercial may refer to: * a dose of advertising conveyed through media (such as - for example - radio or television) ** Radio advertisement ** Television advertisement * (adjective for:) commerce, a system of voluntary exchange of products and se ...
advertisements for local business are also inserted in the programming at the headend (the individual channels, which are distributed nationally, also have their own nationally oriented commercials).


Hybrid fiber-coaxial

Modern cable systems are large, with a single network and headend often serving an entire
metropolitan area A metropolitan area or metro is a region consisting of a densely populated urban core and its less-populated surrounding territories under the same administrative division, sharing industry, infrastructure and housing. A metro area usually comp ...
. Most systems use
hybrid fiber-coaxial Hybrid fiber-coaxial (HFC) is a telecommunications industry term for a broadband network that combines optical fiber and coaxial cable. It has been commonly employed globally by cable television operators since the early 1990s. In a hybrid fibe ...
(HFC) distribution; this means the trunklines that carry the signal from the headend to local neighborhoods are
optical fiber An optical fiber (or fibre in British English) is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit ligh ...
to provide greater bandwidth and also extra capacity for future expansion. At the headend, the electrical signal is translated into an optical signal 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 optical signal is translated back into an electrical signal and carried by
coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric (insulating material); many coaxial cables also have a protec ...
distribution lines on utility poles, from which cables branch out to a series of signal amplifiers and line extenders. These devices carry the signal to customers via passive RF devices called taps.


History in North America

Cable television began in the United States as a commercial business in 1950, although there were small-scale systems by
hobbyist A hobby is considered to be a regular activity that is done for enjoyment, typically during one's leisure time, not professionally or for pay. Hobbies include collecting themed items and objects, engaging in creative and artistic pursuits, pl ...
s in the 1940s. The early systems simply received weak (
broadcast Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began with ...

broadcast
) channels, amplified them, and sent them over unshielded wires to the subscribers, limited to a community or to adjacent communities. The receiving antenna would be taller than any individual subscriber could afford, thus bringing in stronger signals; in hilly or mountainous terrain it would be placed at a high elevation. At the outset, cable systems only served smaller communities without television stations of their own, and which could not easily receive signals from stations in cities because of distance or hilly terrain. In Canada, however, communities with their own signals were fertile cable markets, as viewers wanted to receive American signals. Rarely, as in the college town of
Alfred, New York Alfred is a town in Allegany County, New York, United States. The population was 5,237 at the 2010 census. The Town of Alfred has a village named Alfred in the center of the town. Alfred University and Alfred State College are located in the Vi ...
, U.S. cable systems retransmitted Canadian channels. Although early ( VHF) television receivers could receive 12 channels (2–13), the maximum number of channels that could be broadcast in one city was 7: channels 2, 4, either 5 or 6, 7, 9, 11 and 13, as receivers at the time were unable to receive strong (local) signals on adjacent channels without distortion. (There were frequency gaps between 4 and 5, and between 6 and 7, which allowed both to be used in the same city). As equipment improved, all twelve channels could be utilized, except where a local VHF television station broadcast. Local broadcast channels were not usable for signals deemed to be a priority, but technology allowed low-priority signals to be placed on such channels by synchronizing their
blanking interval In analog video, blanking occurs between horizontal lines and between frames. In raster scan equipment, an image is built up by scanning an electron beam from left to right across a screen to produce a visible trace of one scan line, reducing the b ...
s. TV's were unable to reconcile these blanking intervals and the slight changes to due to travel through a medium, causing ghosting (television), ghosting. The bandwidth of the amplifiers also was limited, meaning frequencies over 250 MHz were difficult to transmit to distant portions of the coaxial network, and UHF channels could not be used at all. To expand beyond 12 channels, non-standard "midband" channels had to be used, located between the FM band and Channel 7, or "superband" beyond Channel 13 up to about 300 MHz; these channels initially were only accessible using separate tuner boxes that sent the chosen channel into the TV set on Channel 2, 3 or 4. Initially, UHF broadcast stations were at a disadvantage because the standard TV sets in use at the time we’re unable to receive their channels. Around 1966 the FCC mandated that all TV sets sold after a certain date were required to have the capability of receiving UHF channels. Before being added to the cable box itself, these midband channels were used for early incarnations of pay TV, e.g. The Z Channel (Los Angeles) and
HBO Home Box Office (HBO) is an American pay television network owned by WarnerMedia Studios & Networks and the flagship property of parent subsidiary Home Box Office, Inc. Maintaining a general entertainment format, programming featured on the ne ...
but transmitted in the clear i.e. not scrambled as standard TV sets of the period could not pick up the signal nor could the average consumer `de-tune' the normal stations to be able to receive it. Once tuners that could receive select mid-band and super-band channels began to be incorporated into standard television sets, broadcasters were forced to either install scrambling circuitry or move these signals further out of the range of reception for early cable-ready TVs and VCRs. However, once consumer sets had the ability to receive all 181 FCC allocated channels, premium broadcasters were left with no choice but to scramble. Unfortunately for pay-TV operators, the descrambling circuitry was often published in electronics hobby magazines such as ''Popular Science'' and ''Popular Electronics'' allowing anybody with anything more than a rudimentary knowledge of broadcast electronics to be able to build their own and receive the programming without cost. Later, the cable operators began to carry
FM radio in Henderson, Nevada and broadcasts at a frequency of 95.5 MHz. FM broadcasting is a method of radio broadcasting using frequency modulation (FM). Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide hig ...
stations, and encouraged subscribers to connect their FM stereo sets to cable. Before multichannel television sound, stereo and bilingual TV sound became common, Pay-TV channel sound was added to the FM stereo cable line-ups. About this time, operators expanded beyond the 12-channel dial to use the "midband" and "superband" VHF channels adjacent to the "high band" 7–13 of North American television frequencies. Some operators as in Cornwall, Ontario, used a dual distribution network with Channels 2–13 on each of the two cables. During the 1980s, United States regulations not unlike public, educational, and government access (PEG) created the beginning of cable-originated live television programming. As cable penetration increased, numerous cable-only TV stations were launched, many with their own news bureaus that could provide more immediate and more localized content than that provided by the nearest network newscast. Such stations may use similar on-air branding as that used by the nearby broadcast network affiliate, but the fact that these stations do not broadcast over the air and are not regulated by the FCC, their call signs are meaningless. These stations evolved partially into today's over-the-air digital subchannels, where a main broadcast TV station e.g. NBS 37* would – in the case of no local CNB or ABS station being available – rebroadcast the programming from a nearby affiliate but fill in with its own news and other community programming to suit its own locale. Many live local programs with local interests were subsequently created all over the United States in most major media market, television markets in the early 1980s. This evolved into today's many cable-only broadcasts of diverse programming, including cable-only produced television film, television movies and miniseries. Cable specialty channels, starting with channels oriented to show movies and large sporting or performance events, diversified further, and "narrowcasting" became common. By the late 1980s, cable-only signals outnumbered broadcast signals on cable systems, some of which by this time had expanded beyond 35 channels. By the mid-1980s in Canada, cable operators were allowed by the regulators to enter into distribution contracts with cable networks on their own. By the 1990s, tiers became common, with customers able to subscribe to different tiers to obtain different selections of additional channels above the basic selection. By subscribing to additional tiers, customers could get specialty channels, movie channels, and foreign channels. Large cable companies used addressable descramblers to limit access to Pay television, premium channels for customers not subscribing to higher tiers, however the above magazines often published workarounds for that technology as well. During the 1990s, the pressure to accommodate the growing array of offerings resulted in digital transmission that made more efficient use of the VHF signal capacity; fibre optics was common to carry signals into areas near the home, where coax could carry higher frequencies over the short remaining distance. Although for a time in the 1980s and 1990s, television receivers and VCRs were equipped to receive the mid-band and super-band channels. Due to the fact that the descrambling circuitry was for a time present in these tuners, depriving the cable operator of much of their revenue, such cable-ready tuners are rarely used now – requiring a return to the set-top boxes used from the 1970s onward. The conversion to digital broadcasting has put all signals – broadcast and cable – into digital form, rendering analog cable television service mostly obsolete, functional in an ever-dwindling supply of select markets. Analog television sets are still accommodated, but their tuners are mostly obsolete, oftentimes dependent entirely on the set-top box.


Deployments by continent

Cable television is mostly available in North America, Europe, Australia, South Asia 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" Multichannel Multipoint Distribution Service, microwave-based systems are used instead.


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 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 television network, 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 31.2 Kbp/s 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 (telecommunications), triple play", regardless of whether CATV or Telephone company, telcos offer it.


See also

* AllVid * CableCARD * Closed-circuit television, "CCTV" as closed-circuit television—not to be confused with CATV *
DOCSIS Data Over Cable Service Interface Specification is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable television operators to ...
*
DVB-C DVB-C stands for "Digital Video Broadcasting - Cable" and it is the DVB European consortium standard for the broadcast transmission of digital television over cable. This system transmits an MPEG-2 or MPEG-4 family digital audio/digital video stre ...
* European cable television frequencies * List of cable television companies * Multichannel video programming distributor * North American television frequencies * Private cable operator * QAM (television) * Satellite television * Switched video * Tru2way


References


Further reading


The history of Rediffusion by Gerald K Clode
* Eisenmann, Thomas R.

''Harvard Business School Weekly Newsletter'', July 10, 2000 * Moss, Mitchell L.; Payne, Frances
"Can Cable Keep Its Promise?"
''New York Affairs'', Volume 6, Number 4. New York University. 1981 * Smith, Ralph Lee, "The Wired Nation", ''The Nation'' magazine, May 18, 1970 * Smith, Ralph Lee, ''The Wired Nation; Cable TV: the electronic communications highway''. New York, Harper & Row, 1972. *


External links

* {{DEFAULTSORT:Cable Television Cable television, American inventions