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| [[broadcasting]] and receiving [[Film|moving picture]]s and [[sound]] over a distance. The term has come to refer to all the aspects of television from the [[television set]] to the [[television program|programming]] and [[Transmission (telecommunications)|transmission]]. The word is derived from mixed [[Latin ]] and [[Greek language|Greek]] roots, meaning "far sight": Greek ''{{polytonic|τῆλε}}'' "tele", far, and Latin ''visio-n'', sight (from ''video, vis-'' to see). | | [[broadcasting]] and receiving [[Film|moving picture]]s and [[sound]] over a distance. The term has come to refer to all the aspects of television from the [[television set]] to the [[television program|programming]] and [[Transmission (telecommunications)|transmission]]. The word is derived from mixed [[Latin ]] and [[Greek language|Greek]] roots, meaning "far sight": Greek ''{{polytonic|τῆλε}}'' "tele", far, and Latin ''visio-n'', sight (from ''video, vis-'' to see). |
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| == History ==
| | The first television broadcasts with a modern level of definition (more than 240 lines) were made in England in 1936. So-called "System A" used 405 lines. The BBC made its inaugural broadcasts on a dual-system television system in November of [[1936]], alternating between the Baird system (which used film as an intermediary) and the all-electronic EMI system, which used Zworykin's tubes. The Baird system was eventually abandoned in favor of the EMI, but the outbreak of the [[Second World War]] caused the BBC service to be suspended on [[September 1]], [[1939]]. It did not resume until [[June 7]], [[1946]]. |
| {{Main article|History of television}}
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| The origins of what would become today's television system can be traced back as far as the discovery of the [[photoconductivity]] of the element [[selenium]] by [[Willoughby Smith]] in 1873 and the invention of a scanning disk by [[Paul Nipkow]] in 1884. All practical television systems use the fundamental idea of scanning an image to produce a time series signal representation. That representation is then transmitted to a device to reverse the scanning process. The final device, the television, relies on the human eye to integrate the result into a coherent image.
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| Electromechanical techniques were developed prior to World War II, most notably by [[Charles Francis Jenkins]] and [[John Logie Baird]]. Baird gave the world's first public demonstration of a working television system to members of the Royal Institution and a newspaper reporter on [[26 January]] [[1926]] at his laboratory in London. Baird further demonstrated the world's first [[color television]] transmission on [[3 July]] 1928. He also produced the first transatlantic television signal, as well as the earliest scheduled television broadcasts, via the BBC, in the early 1930's.
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| Completely electronic television systems relied on the inventions of [[Philo Taylor Farnsworth]], [[Vladimir Zworykin]] and others to produce a system suitable for mass distribution of television programming. Commercial broadcast programming, following years of experimental broadcasts seen only in a few specially-equipped homes, occurred in both the United States and the United Kingdom before World War II.
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| The first television broadcasts with a modern level of definition (more than 240 lines) were made in England in 1936. So-called "System A" used 405 lines. The BBC made its inaugural broadcasts on a dual-system television system in November of [[1936]], alternating between the Baird system (which used film as an intermediary) and the all-electronic EMI system, which used Zworykin's tubes. The Baird system was eventually abandoned in favor of the EMI, but the outbreak of the [[Second World War]] caused the BBC service to be suspended on [[September 1]], [[1939]]. It did not resume until [[June 7]], [[1946]]. | |
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| While Television broadcasts recommenced in [[1946]] after the war's end, it did not become common in United States homes until the middle 1950s. While North American over-the-air broadcasting was originally free of direct marginal cost to the consumer (i.e., cost in excess of acquisition and upkeep of the hardware) and broadcasters were compensated primarily by receipt of advertising revenue, increasingly United States television consumers obtain their programming by subscription to cable television systems or direct-to-home satellite transmissions. In the United Kingdom, on the other hand, the owner of each television must pay a [[Television licence|licence fee]] annually which is used to support the [[BBC|British Broadcasting Corporation]].
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| ==Technology==
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| ===Elements of a television system===
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| The elements of a simple television system are:
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| * An image source - this may be a [[Professional video camera|camera]] for live pick-up of images or a [[flying spot scanner]] for transmission of [[motion picture|films]]
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| * A sound source.
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| * A [[transmitter]], which modulates one or more [[television signal]]s with both picture and sound information for transmission.
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| * A receiver (television) which recovers the picture and sound signals from the television broadcast.
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| * A display device, which turns the electrical signals into visible light and audible sound.
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| Practical television systems include equipment for selecting different image sources, mixing images from several sources at once, insertion of pre-recorded video signals, synchronizing signals from many sources, and direct image generation by computer for such purposes as station identification. Transmission may be over the air from land-based transmitters, over metal or optical cables, or by radio from synchronous [[Satellite television|satellite]]s. Digital systems may be inserted anywhere in the chain to provide better image transmission quality, reduction in transmission [[bandwidth]], special effects, or security of transmission from reception by non-subscribers.
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| <!-- Elements of a television system - block diagram here -->
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| <!-- Image source, camera, film, magnetic tape, exceptionally computer-generated images-->
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| <!-- Sound source -->
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| <!-- Transmitter, over the air, bandwidth required, antenna, satellite system, cable system, digital encoding, scrambling -->
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| <!-- Receiver, antenna, cable connection, satellite down-converter, digital decode, descramble-->
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| <!-- Display, cathode ray tube, color tube, now LCD, historically mechanical scanned lamp-->
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| <!-- Recorder, analog magnetic tape, now digital -->
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| ===Display technology===
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| Thanks to advances in display technology, there are now several kinds of video displays used in modern TV sets:
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| *'''CRT''': The most common displays are direct-view [[cathode ray tube|CRT]]s for up to 40 in (100 cm) (in 4:3) and 46 in (115 cm) (in 16:9) [[diagonal]]ly. These are still the least expensive, and are a refined technology that can still provide the best overall picture quality. As they do not have a fixed [[native resolution]], in some cases they are also capable of displaying sources with a variety of different resolutions at the best possible image quality. The [[frame rate]] or refresh rate of a typical [[NTSC]] format CRT TV is 60 Hz, and for the [[PAL]] format, it is 50 Hz. A typical [[NTSC]] broadcast signal's visible portion has an equivalent resolution of about 640x480 pixels. It actually could be slightly higher than that, but the [[Vertical blanking interval|Vertical Blanking Interval]], or VBI, allows other signals to be carried along with the broadcast.
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| *'''Rear projection''': Most very large screen TVs (up to over 100 inch (254 cm)) use [[projection]] technology. Three types of projection systems are used in projection TVs: CRT-based, [[Liquid crystal display|LCD]]-based, and [[DLP]] (reflective micromirror chip) -based. Projection television has been commercially available since the 1970s, but at that time could not match the image sharpness of the CRT; current models are vastly improved, and offer a cost-effective large-screen display. A variation is a [[video projector]], using similar technology, which projects onto a [[Projection screen|screen]].
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| *'''Flat panel LCD''' or '''plasma''': Modern advances have brought [[Flat panel display|flat panel]]s to TV that use [[Active-matrix liquid crystal display|active matrix]] [[liquid crystal display|LCD]] or [[plasma display]] technology. Flat panel LCDs and [[plasma display]]s are as little as 1 inch thick and can be hung on a wall like a picture or put over a [[pedestal]]. Some models can also be used as [[Computer display|computer monitor]]s.<br>{{seealso|Liquid crystal display television}}
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| It is important to think about the living environment of your television before deciding on a single display technology. Each has its pros and cons. Flat panel LCD display can have narrow viewing angles and so may not suit a home environment. Rear projection screens do not perform well in natural [[daylight]] or well lit rooms and so are best suited to dark viewing areas. A complete run down of the [[Comparison of display technology|pros and cons]] of each display should be sought before purchasing a single television technology.
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| ===Terminology for televisions===
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| Pixel [[Display resolution|resolution]] is the amount of individual points known as [[pixels]] on a given screen. A typical resolution of 800x600 means that the television display has 800 pixels across and 600 pixels on the vertical axis. The higher the resolution on a specified display the sharper the image.
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| Contrast [[ratio]] is a measurement of the range between the brightest and darkest points on the screen. The higher the contrast ratio, the better looking picture there is in terms of richness, deepness, and [[shadow]] detail.
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| The [[brightness]] of a picture measures how vibrant and impacting the colours are. Measured in <math>cd/m^2</math> equivalent to the amount of candles required to power the [[image]].
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| ===Transmission band===
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| There are various bands of frequencies on which televisions work depending upon the country. The VHF and UHF signals in bands III to V are generally used. Lower frequencies do not have enough [[bandwidth]] available for television. Although the [[BBC]] initially used Band I VHF at 45 MHz, this frequency is no longer in use for this purpose. Band II is used for FM radio transmissions. Higher frequencies behave more like light and do not penetrate buildings or travel around obstructions well enough to be used in a conventional broadcast TV system, so they are generally only used for satellite broadcasting, which uses frequencies around 10 GHz. TV systems in most countries relay the video as an AM ([[amplitude-modulation]]) signal and the sound as a FM ([[frequency-modulation]]) signal. An exception is [[France]], where the sound is AM.
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| ===Aspect ratios===
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| '''[[Aspect ratio (image)|Aspect ratio]]''' refers to the ratio of the horizontal to vertical measurements of a television's picture. Mechanically scanned television as first demonstrated by [[John Logie Baird]] in 1926 used a 7:3 vertical aspect ratio, oriented for the head and shoulders of a single person in close-up.
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| Most of the early electronic TV systems from the mid-1930s onward shared the same [[aspect ratio (image)|aspect ratio]] of 4:3 which was chosen to match the [[Academy ratio|Academy Ratio]] used in cinema films at the time. This ratio was also square enough to be conveniently viewed on round [[cathode ray tube|cathode-ray tube]]s (CRTs), which were all that could be produced given the [[manufacturing]] [[technology]] of the time. (Today's CRT technology allows the manufacture of much wider tubes, and the flat-screen technologies which are becoming steadily more popular have no technical aspect ratio limitations at all.) The [[BBC]]'s television service used a more squarish [http://tcc.members.beeb.net/tchistory.html 5:4] ratio from 1936 to [http://www.pembers.freeserve.co.uk/Test-Cards/Test-Card-Technical.html#Aspect-Ratio 3 April 1950], when it too switched to a 4:3 ratio. This did not present significant problems, as most sets at the time used round tubes which were easily adjusted to the 4:3 ratio when the transmissions changed.
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| In the 1950s, [[movie studio]]s moved towards [[widescreen]] aspect ratios such as [[CinemaScope]] in an effort to distance their product from television. Although this was initially just a [[gimmick]], widescreen is still the format of choice today and square aspect ratio movies are rare. Some people argue that widescreen is actually a disadvantage when showing objects that are tall instead of [[panorama|panoramic]], others say that natural vision is more panoramic than tall, and therefore widescreen is easier on the eye.
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| The switch to [[digital television]] systems has been used as an opportunity to change the standard television picture format from the old ratio of 4:3 (1.33:1) to an aspect ratio of 16:9 (approximately 1.78:1). This enables TV to get closer to the aspect ratio of modern widescreen [[film|movie]]s, which range from 1.66:1 through 1.85:1 to 2.35:1. There are two methods for transporting widescreen content, the better of which uses what is called [[full screen anamorphic|anamorphic widescreen]] format. This format is very similar to the technique used to fit a widescreen movie frame inside a 1.33:1 35mm film frame. The image is compressed horizontally when recorded, then expanded again when played back. The anamorphic widescreen 16:9 format was first introduced via European [[PALPlus]] television broadcasts and then later on "widescreen" [[DVD]]s; the [[ATSC]] [[High-definition television|HDTV]] system uses straight widescreen format, no horizontal compression or expansion is used.
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| Recently "widescreen" has spread from television to computing where both [[desktop computer|desktop]] and [[laptop]] computers are commonly equipped with widescreen displays. There are some complaints about distortions of movie picture ratio due to some DVD playback software not taking account of aspect ratios; but this may subside as the DVD playback software matures. Furthermore, computer and laptop widescreen displays are in the 16:10 aspect ratio both physically in size and in pixel counts, and not in 16:9 of consumer televisions, leading to further complexity. This was a result of widescreen computer display engineers' uninformed assumption that people viewing 16:9 content on their computer would prefer that an area of the screen be reserved for playback controls or [[subtitle]]s, as opposed to viewing content full-screen.
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| =====Aspect ratio incompatibility=====
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| The television industry's changing of [[Aspect ratio (image)|aspect ratio]]s is not without difficulties, and can present a considerable problem.
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| Displaying a widescreen aspect (rectangular) image on a conventional aspect (square or 4:3) display can be shown:
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| *in "[[letterbox]]" format, with black horizontal bars at the top and bottom
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| *with part of the image being cropped, usually the extreme left and right of the image being cut off (or in "[[pan and scan]]", parts selected by an operator)
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| *with the image horizontally compressed
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| A conventional aspect (square or 4:3) image on a widescreen aspect (rectangular with longer horizon) display can be shown:
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| *in "[[pillar box (film)|pillar box]]" format, with black vertical bars to the left and right
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| *with upper and lower portions of the image cut off (or in "tilt and scan", parts selected by an operator)
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| *with the image horizontally distorted
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| A common compromise is to shoot or create material at an aspect ratio of 14:9, and to lose some image at each side for 4:3 presentation, and some image at top and bottom for 16:9 presentation. In recent years, the cinematographic process known as [[Super 35 mm film|Super 35]] (championed by [[James Cameron]]) has been used to film a number of major movies such as [[Titanic (1997 film)|''Titanic'']], ''[[Legally Blonde]]'', ''[[Austin Powers]]'', and ''[[Crouching Tiger, Hidden Dragon]]'' (see also: [[List of top-grossing films shot in Super 35]]). This process results in a camera-negative which can then be used to create both wide-screen theatrical prints, and standard "[[full screen]]" releases for television/VHS/DVD which avoid the need for either "[[Letterbox|letterboxing]]" or the severe loss of information caused by conventional "[[pan-and-scan]]" cropping.
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| === Sound ===
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| {{further|[[NICAM]]}}
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| === Television add-ons ===
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| Today there are many television add-ons including [[Computer and video games|Video Game]] Consoles, [[Videocassette recorder|VCR]]s, [[Set-top box]]es for [[Cable television|Cable]], [[Satellite television|Satellite]] and DVB-T compliant [[Digital Television]] reception, [[DVD]] players, or [[Digital video recorder|Digital Video Recorders]] (including personal video recorders, PVRs). The add-on market continues to grow as new technologies are developed.
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| === New developments ===
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| *[[Ambilight]]™
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| *[[Broadcast flag]]
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| *[[CableCARD]]™
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| *[[DLP|Digital Light Processing]] (DLP)
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| *[[Digital Rights Management]] (DRM)
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| *[[Digital television]] (DTV)
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| *[[Digital Video Recorder]]s
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| *[[Direct Broadcast Satellite]] TV (DBS)
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| *[[DVD]]
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| *[[Flicker-free]] (100 Hz or 120 Hz, depending on country)
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| *[[High Definition TV]] (HDTV)
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| *[[High-Definition Multimedia Interface]] (HDMI)
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| *[[IPTV]]
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| *[[Internet television]]
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| *[[Liquid crystal display television|LCD]] and [[Plasma display]] [[Flat panel display|Flat screen]] TV
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| *[[Surface-conduction Electron-emitter Display|SED]] display technology
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| *[[Organic light-emitting diode|OLED]] display technology
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| *[[P2PTV]]
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| *[[Pay-per-view]]
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| *[[Picture-in-picture]] (PiP)
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| *[[Pixelplus]]
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| *[[Remote control]]s
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| *[[Video on-demand]] (VOD)
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| *[[Ultra High Definition Video]] (UHDV)
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| *[[Web TV]]
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| ==Geographical usage==
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| *[[Timeline of the introduction of television in countries]]
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| {{main|Geographical usage of television}}
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| ==Content==
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| ===Advertising===
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| Since their inception in the USA in 1940, [[television commercial|TV commercial]]s have become one of the most effective, most pervasive, and most popular methods of selling products of many sorts, especially consumer goods. U.S. advertising rates are determined primarily by [[Nielsen Ratings]].
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| ===Programming===
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| Getting TV programming shown to the public can happen in many different ways. After production the next step is to market and deliver the product to whatever markets are open to using it. This typically happens on two levels:
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| #'''Original Run''' or '''First Run''' - a producer creates a program of one or multiple episodes and shows it on a station or network which has either paid for the production itself or to which a license has been granted by the producers to do the same.
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| #'''[[Television syndication|Syndication]]''' - this is the terminology rather broadly used to describe secondary programming usages (beyond original run). It includes secondary runs in the country of first issue, but also international usage which may or may not be managed by the originating producer. In many cases other companies, [[TV stations]] or individuals are engaged to do the syndication work, in other words to sell the product into the markets they are allowed to sell into by contract from the copyright holders, in most cases the producers.
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| In most countries, the first wave occurs primarily on [[Free-to-air|free-to-air (FTA)]] television, while the second wave happens on subscription TV and in other countries. In the U.S., however, the first wave occurs on the FTA networks and subscription services, and the second wave travels via all means of distribution.
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| First run programming is increasing on subscription services outside the U.S., but few domestically produced programs are syndicated on domestic FTA elsewhere. This practice is increasing however, generally on digital-only FTA channels, or with subscriber-only first run material appearing on FTA.
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| Unlike the U.S., repeat FTA screenings of a FTA network program almost only occur on that network. Also, [[Affiliate]]s rarely buy or produce non-network programming that isn't centered around local events.
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| == Social aspects ==
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| ===Technology trends===
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| In its infancy, television was an ephemeral medium. Fans of regular shows planned their [[TV listings|schedules]] so that they could be available to watch their shows at their time of broadcast. The term ''appointment television'' was coined by marketers to describe this kind of attachment.
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| The viewership's dependence on schedule lessened with the invention of programmable video recorders, such as the [[Videocassette recorder]] and the [[Digital video recorder]]. Consumers could watch programs on their own schedule once they were broadcast and recorded. Television service providers also offer [[video on demand]], a set of programs which could be watched at any time.
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| Both [[mobile phone]] networks and the [[internet]] are capable of carrying video streams. There is already a fair amount of internet TV available, either live or as downloadable programs. Mobile phone TV is planned to eventually become mainstream, after worldwide over-the-air digital TV takes over analogue and some technical difficulties can be overcome - especially the ones related to battery life.
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| ===Suitability for audience===
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| Almost since the medium's inception there have been charges that some programming is, in one way or another, inappropriate, [[offensive]] or [[decency|indecent]]. Critics such as Jean Kilborne have claimed that television, as well as other mass media images, harm the self image of young girls. Other commentators such as Sut Jhally, make the case that television advertising in the U.S. has been so effective that happiness has increasingly come to be equated with the purchasing of products. [[George Gerbner]] has presented evidence that the frequent portrayals of crime, especially minority crime, has led to the [[Mean World Syndrome]], the view among frequent viewers of television that crime rates are much higher than the actual data would indicate. In addition, a lot of television has been charged with presenting propaganda, political or otherwise, and been pitched at a low intellectual level.
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| ==Further reading==
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| *[[Erik Barnouw]], ''Tube of Plenty: The Evolution of American Television'', Oxford University Press, 1992.
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| *[[Pierre Bourdieu]], ''On Television'', The New Press, 2001.
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| *Brooks, Tim and March, Earle, ''The Complete Guide to Prime Time Network and Cable TV Shows'', Ballantine, Eighth Edition, 2002.
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| *[[Guy Debord]], ''The Society of the Spectacle'', Zone Books, 1995.
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| *[[Jacques Derrida]], [[Bernard Stiegler]], ''Echographies of Television'', Polity Press, 2002.
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| *[[Jerry Mander]], ''Four Arguments for the Elimination of Television'', Perennial, 1978.
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| * [[Neil Postman]], ''[[Amusing Ourselves to Death]]: Public Discourse in the Age of Show Business''. Penguin USA, 1985. ISBN 0-670-80454-1
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| *Dr. Aric Sigman, ''Remotely Controlled: How Television Is Damaging Our Lives — And What We Can Do About It'', Vermilion, 2005.
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| *Beretta E. Smith-Shomade, ''Shaded Lives: African-American Women and Television'', Rutgers University Press, 2002.
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| ==References==
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| *David E. Fisher and Marshall J. Fisher, ''Tube: the Invention of Television'', Counterpoint, Washington D.C. USA, (1996) ISBN 1-887178-17-1
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| *Albert Abramson, ''The History of Television, 1942 to 2000'', McFarland, Jefferson, NC, USA, and London (2003) ISBN 0-7864-1220-8
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| ==See also==
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| * [[Golden Age of Television]]
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| * [[Archive of American Television]]
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| * [[BARB]]
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| * [[Composite monitor]]
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| * [[Compression]]
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| * [[Digital Video]]
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| * [[European Broadcasting Union]] ([[EBU]])
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| * [[Electronic field production]]
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| * [[Electronic news gathering]]
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| * [[History of television]]
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| * [[List of television topics]]
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| * [[List of 'years in television']]
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| * [[Lists of television channels]]
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| * [[List of television programs|List of television programs/series]]
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| * [[List of television personalities]]
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| * [[Live television]]
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| * [[Museum of Broadcast Communications]]
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| * [[PC card]]
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| * [[PVR]] ([[Personal Video Recorder]]).
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| * [[S-video monitor]]
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| * [[Teletext]]
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| * [[Time code]]
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| * [[TV/VCR combo]]
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| * [[TV/FM DX|Long distance television reception (TV DX)]]
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| * [[TV listings]]
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| ==External links==
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| {{sisterlinks|Television}}
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| * [http://www.bbc.co.uk/tv/ BBC Television]
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| * [http://www.gooya.co.uk/worldtv.html A directory of world television channels]
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| * [http://www.tvhistory.tv/ Television History — The First 75 Years]
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| * [http://www.lcdplasmatvguide.com/ TV Type Guide]
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| * [http://www.museum.tv/archives/etv/index.html The Encyclopedia of Television] at the [[Museum of Broadcast Communications]]
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| * [http://www.mztv.com MZTV Museum of Television] Some of the rarest sets in America
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| * [http://www.the-best-of-television.com/ The #1 Online Television Resource]
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| * [http://www.cherishedtelevision.co.uk/home.html Cherished Television]
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| * [http://www.metvwiki.com/index.php/Main_Page CNET News.com's Me TV Wiki, about the future of television].
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| * [http://www.infopaw.com/movies_tv.htm Cross-search TV shows, TV forums, TV critics, and Hollywood news]
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| [[Category:CZ Live]] | | [[Category:CZ Live]] |
