Teletext (or "broadcast teletext") is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules. Subtitle (or closed captioning) information is also transmitted in the teletext signal, typically on page 888[1] or 777.
A number of similar teletext services were developed in other countries, some of which attempted to address the limitations of the British-developed system, with its simple graphics and fixed page sizes.
Teletext was created in the United Kingdom in the early 1970s. Different systems existed, but by the end of the decade they converged, with the creation of the World System Teletext (WST). WST remained in use for analogue broadcasts until 2012.
The first test transmissions were made by the BBC in 1972–74, with the name Ceefax ("see facts"). The Ceefax system went live on 23 September 1974 with thirty pages of information. Due to the adoption of a common teletext standard (WST), the Ceefax system ceased in 1976. The name was retained for the service itself, that continued after that year using the WST standard.
ORACLE was first broadcast on the ITV network in the mid-late 1970s. Due to the adoption of a common teletext standard (WST), the ORACLE system ceased in 1976. The name was retained for the service itself, that continued after that year using the WST standard.
World System Teletext (or WST) is the name of a standard for teletext throughout Europe today. Almost all television sets sold in Europe since the early ’80s have built-in WST-standard teletext decoders as a feature.
It originally stems from the UK standards developed by the BBC (Ceefax) and the UK Independent Broadcasting Authority (ORACLE) in 1974 for teletext transmission, extended in 1976 as the Broadcast Teletext Specification.
With some tweaks to allow for alternative national character sets, and adaptations to the NTSC 525-line system as necessary, this was then promoted internationally as "World System Teletext".
It was accepted by CCIR in 1986 as CCIR Teletext System B, one of four recognised standards for teletext worldwide.
In France, where the SECAM standard is used in television broadcasting, a teletext system was developed in the late 1970s under the name Antiope. It had a higher data rate and was capable of dynamic page sizes, allowing more sophisticated graphics. It was phased out in favour of standard teletext in 1991.
The CBC ran a teletext service, IRIS, accessible only in Calgary, Toronto and Montreal. It ran from 1983 until about 1986, and used the Canadian-developed Telidon system, which was developed in 1980. Like Antiope, Telidon allowed significantly higher graphic resolution than standard teletext.
United States
Adoption in the United States was hampered due to a lack of a single teletext standard and consumer resistance to the high initial price of teletext decoders. Throughout the period of analogue broadcasting, teletext or other similar technologies in the US were practically non-existent, with the only technologies resembling such existing in the country being closed captioning, TV Guide On Screen, and Extended Data Services (XDS).
Early tests
A version of the European teletext standard designed to work with the NTSC television standard used in North America was first demonstrated in the US in 1978 by station KSL in Salt Lake City, Utah, premiered a teletext service using Ceefax. They were followed by American television network CBS, which decided to try both the British Ceefax and French Antiope software for preliminary tryouts for a teletext service, using station KMOX (now KMOV) in St. Louis, Missouri as a testing ground.[2][3]
CBS decided on Antiope and mounted a large market trial in Los Angeles in partnership with NBC and Public Broadcasting Service (PBS) Public television. Services premiered simultaneously on station KNXT (now KCBS-TV), KNBC and KCET in Los Angeles.[4][5] All three services included an array of local news and information services. KCET's service also included service components for use in schools.
Later, an official North American standard of teletext, called NABTS (North American Broadcast Teletext Specification) was developed in the early 1980s by Norpak, a Canadian company. NABTS provided improved graphic and text capability over WST, but was quite short-lived. This was mainly due to the expensive cost of NABTS decoders, costing in the thousands of dollars upon their release to the public. NABTS, however, was adopted for a short while by American TV networks NBC & CBS throughout the early-to-mid 80s, CBS using it for their short-lived ExtraVision teletext service, which premiered after the early Antiope & Ceefax trials by CBS & KNXT, and NBC, who had a NABTS-based service called NBC Teletext for a very short time in the mid-1980s. NBC discontinued their service in 1985 due to the cost of NABTS decoders not dropping to an affordable level for the consumer public.[6]
WST was also used for a short time in the US, with services provided throughout the late 1970s and early 1980s by several regional American TV networks (such as the University of Wisconsin–Madison's Infotext service in the mid-1980s, which was carried on several TV stations across Wisconsin, and Agtext, provided by Kentucky Educational Television and carried on KET's stations, both services providing agriculturally oriented information) and major-market U.S. TV stations (such as Metrotext, which was formerly carried on station KTTV in Los Angeles, and KeyFax, formerly on WFLD in Chicago).
WST-based service Electra
Perhaps the most prominent of American teletext providers was the Electra teletext service, using WST, which was broadcast starting in the early 1980s on the vertical blanking interval (VBI) of the American cable channel WTBS. Electra was owned and operated by Taft Broadcasting and Satellite Syndicated Systems (SSS). Electra ran up until 1993, when it was shut down due to Zenith, the prominent (and only) American TV manufacturer at the time offering teletext features in their sets decided to discontinue such features, as well as a lack of funding and lagging interest in teletext by the American consumer.
Zenith manufactured models of television sets in the US in the 1980s, most notably their Digital System 3 line, that had built-in WST teletext decoders as a feature, much like most British/European TV sets. Teletext services in the US like Electra could be received with one of these sets, but these were mostly more expensive higher-end sets offered by Zenith, possibly causing Electra (and American teletext in general) to never catch on with the public.
Australian company Dick Smith Electronics (DSE) also offered through their US distributors a set-top WST teletext decoder kit. The kit used as its core the same teletext decoding module (manufactured by UK electronics company Mullard) installed in most British TV sets, with additional circuitry to adapt it for American NTSC video, and to utilize it in a separate set-top box.
A significant reason for the demise of American teletext was when Zenith introduced built-in closed captioning decoders in TVs in the early '90s, as mandated by the FCC. It was not practical for Zenith to re-design their TV chassis models that previously had teletext decoder support to have both teletext and closed captioning support. So Zenith decided to drop the teletext features, therefore ending teletext service in the US in the early 1990s, considering Zenith was the only major manufacturer of teletext-equipped sets in the United States.
InterCast was a modern teletext-like system created by Intel in 1996, using a TV tuner card installed in a desktop PC running Windows with the InterCast Viewer software. The software would receive data representing HTML pages via the VBI (Vertical Blanking Interval) of a television channel's video, while displaying in a window in the InterCast software the TV channel itself. The HTML data received would then be displayed in another window in the Intercast software. It usually was extra supplemental information relevant to the TV program being viewed, such as extra clues for the viewer during a murder mystery show, or extra news headlines or extended weather forecasts during a newscast.
NBC, as well as The Weather Channel, CNN and M2 (now MTV2), utilized InterCast technology to complement their programming. InterCast, however, fell into disuse, and Intel discontinued support of InterCast a few years later.
WaveTop
Another service in the US similar in delivery and content to teletext was the WaveTop service, provided and operated by the Wavephore Corporation. It used the same types of InterCast-compatible TV tuner cards, and used an application that ran under Windows, like InterCast. In fact, WaveTop software was also bundled with TV tuner cards that had InterCast software bundled with them as well.
However, Wavetop was an independent service from InterCast, and wasn't a complementary service to a television program or channel like the latter. In fact, viewing television with a TV card was not possible while the WaveTop software was running, since the software utilized the TV tuner card as a full-time data receiver.
WaveTop provided content from several different providers in the form of HTML pages displayed in the WaveTop software, such as news articles from the New York Times, weather information provided by The Weather Channel, and sports from ESPN. It also delivered short video clips, usually commercials, that could be viewed in the software as well.
When it was in operation, WaveTop's data was delivered on the VBI of local public TV stations affiliated with PBS through their PBS National Datacast[7] division, that the WaveTop software tuned the TV card to in order to receive the service.
Yet another service in the U.S. that relied on data delivery via the VBI like teletext, was the Guide+ (Guide Plus, also referred to as GuidePlus+ as well) service provided and developed by Gemstar. There were several models of television sets made throughout the 90s by Thomson Consumer Electronics under the RCA and General Electric brands that had built-in Guide+ decoders. Guide+ was an on-screen interactive program guide that provided current TV schedule listings, as well as other information like news headlines. Some Guide+ equipped sets from RCA even had an IR-emitting sensor that could be plugged into the back of the TV, to control a VCR to record programs which could be selected from the on-screen Guide+ listings. In some ways, this was very similar to the Video Programming by Teletext|Video Programming by Teletext (VPT), Video Program System (VPS), and Programme Delivery Control (PDC) features of British/European teletext.
Guide+ was a free service, supported by advertisements displayed on-screen in the Guide+ menu and listing screens, not unlike banner ads displayed on web pages. Guide+ was delivered over the VBI of select local American TV stations.
Guide+ was discontinued by Gemstar in June 2004, and soon afterwards, Thomson dropped the Guide+ features from all RCA and GE television sets made afterward.
However, Guide+ in the United States has now been replaced by Gemstar with a similar service (delivered in the same fashion via VBI like Guide+), called TV Guide On Screen.[8] A small number of televisions, DVD recorders, and digital video recorders are now being released with TV Guide On Screen capabilities. The Guide+ name & service is still used in Europe by Gemstar. (The same service is known in Japan as G-Guide).
Star Sight
Similar to Guide+ was Star Sight,[9] with its decoders built into TVs manufactured by Zenith, Samsung, Sony, Toshiba, Magnavox, and others. This was an electronic program guide service similar to Guide+, but was a service that relied on monthly subscription fees paid by the user, not from revenue gathered from on-screen advertisements like Guide+. Star Sight discontinued operations on July 21, 2003, due to a lack of subscribers to the service. Star Sight's data was also delivered on the VBI of local PBS stations through the PBS National Datacast division, much like how WaveTop was delivered as mentioned previously in this article.
Related Research Articles
A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of signal, turning the source signal into content in a form that can then be displayed on the television screen or other display device. They are used in cable television, satellite television, and over-the-air television systems as well as other uses.
Closed captioning (CC) and subtitling are both processes of displaying text on a television, video screen, or other visual display to provide additional or interpretive information. Both are typically used as a transcription of the audio portion of a program as it occurs, sometimes including descriptions of non-speech elements. Other uses have included providing a textual alternative language translation of a presentation's primary audio language that is usually burned-in to the video and unselectable.
NAPLPS is a graphics language for use originally with videotex and teletext services. NAPLPS was developed from the Telidon system developed in Canada, with a small number of additions from AT&T Corporation. The basics of NAPLPS were later used as the basis for several other microcomputer-based graphics systems.
Telidon was a videotex/teletext service developed by the Canadian Communications Research Centre (CRC) during the late 1970s and supported by commercial enterprises led by Infomart in the early 1980s. The CRC referred to Telidon as a "second generation" system, offering improved performance, 2D colour graphics, multilingual support and a number of different interactivity options supported on various hardware. With additional features added by AT&T Corporation, and 16 other contributors in North America and supported by the Federal Government, Telidon was redefined as a protocol and became the NAPLPS standard.
Videotex was one of the earliest implementations of an end-user information system. From the late 1970s to early 2010s, it was used to deliver information to a user in computer-like format, typically to be displayed on a television or a dumb terminal.
Ceefax was the world's first teletext information service and a forerunner to the current BBC Red Button service. Ceefax was started by the BBC in 1974 and ended, after 38 years of broadcasting, at 23:32:19 BST on 23 October 2012, in line with the digital switchover being completed in Northern Ireland.
Programme delivery control (PDC) is specified by the standard ETS 300 231, published by the European Telecommunications Standards Institute (ETSI). This specifies the signals sent as hidden codes in the teletext service, indicating when transmission of a programme starts and finishes.
The term telesoftware was coined by W.J.G. Overington who first proposed the idea; it literally means “software at a distance” and it often refers to the transmission of programs for a microprocessor or home computer via broadcast teletext, though the use of teletext was just a convenient way to implement the invention, which had been invented as a theoretical broadcasting concept previously. The concept being of producing local interactivity without the need for a return information link to a central computer. The invention arose as spin-off from research on function generators for a hybrid computer system for use in simulation of heat transfer in food preservation, and thus from outside of the broadcasting research establishments.
Antiope was a French teletext standard in the 1980s. It also formed the basis for the display standard used in the French videotex service Minitel.
EIA-608, also known as "line 21 captions" and "CEA-608", was once the standard for closed captioning for NTSC TV broadcasts in the United States, Canada and Mexico. It also specifies an "Extended Data Service", which is a means for including a VCR control service with an electronic program guide for NTSC transmissions that operates on the even line 21 field, similar to the TeleText based VPS that operates on line 16 which is used in PAL countries.
Datacasting is the broadcasting of data over a wide area via radio waves. It most often refers to supplemental information sent by television stations along with digital terrestrial television, but may also be applied to digital signals on analog TV or radio. It generally does not apply to data which is inherent to the medium, such as PSIP data which defines virtual channels for DTT or direct broadcast satellite systems; or to things like cable modem or satellite modem, which use a completely separate channel for data.
MovieBeam was a video-on-demand service started by The Walt Disney Company, specifically its subsidiary Buena Vista Datacasting, LLC. Movies were sent wirelessly into the subscriber's home by embedding digital data (datacasting) within local Public Broadcasting Service (PBS) stations' analog TV (NTSC) broadcast to deliver the movies to a set-top box. The data was embedded using dNTSC technology licensed from Dotcast, and distributed to TV stations via National Datacast. Up to 10 new movies were delivered to the player each week. The player also contained free movie trailers, previews, and other extras.
NABTS, the North American Broadcast Teletext Specification, is a protocol used for encoding NAPLPS-encoded teletext pages, as well as other types of digital data, within the vertical blanking interval (VBI) of an analog video signal. It is standardized under standard EIA-516, and has a rate of 15.6 kbit/s per line of video.
Teletext, or broadcast teletext, is a videotex standard for displaying text and rudimentary graphics on suitably equipped television sets. Teletext sends data in the broadcast signal, hidden in the invisible vertical blanking interval area at the top and bottom of the screen. The teletext decoder in the television buffers this information as a series of "pages", each given a number. The user can display chosen pages using their remote control.
Electra was a teletext service in the United States that was in operation from the early 1980s up until 1993, when it was shut down due to a lack of funding, and discontinuation of teletext-capable television sets by the only US television manufacturer offering teletext capability at the time, Zenith. It was owned, operated and maintained by Cincinnati-based Taft Broadcasting and Tulsa, Oklahoma-based Satellite Syndicated Systems (SSS), in cooperation with cable/satellite TV station Superstation WTBS, who carried Electra's data on their vertical blanking interval. SSS' own TV network, the Satellite Program Network, carried the service before it was shut down in 1989. The service was also available to C-band satellite dish users via the Galaxy 1 and Satcom 3R satellites.
Guide Plus+, TV Guide On Screen, TV Guide Daily, TV Guide Plus+ and Guide Plus+ Gold or G-Guide are brand names for an interactive electronic program guide (EPG) system that is used in consumer electronics products, such as television sets, DVD recorders, personal video recorders, and other digital television devices. It offers interactive on-screen program listings that enable viewers to navigate, sort, select and schedule television programming for viewing and recording. The differing names are only used for marketing purposes – the entire system is owned by Rovi Corporation, the successor to Gemstar-TV Guide International. In 2016, Rovi acquired digital video recorder maker TiVo Inc., and renamed itself TiVo Corporation.
ExtraVision was a short-lived teletext service created and operated by the American television network CBS in the early to mid-1980s. It was carried in the vertical blanking interval of the video from local affiliate stations of the CBS network. It featured CBS program information, news, sports, weather, even subtitling for CBS programming. ExtraVision could also have its pages customized by the local affiliate station carrying it, for such things as program schedules, local community announcements, and station promotions.
Intercast was a short-lived technology developed in 1996 by Intel for broadcasting information such as web pages and computer software, along with a single television channel. It required a compatible TV tuner card installed in a personal computer and a decoding program called Intel Intercast Viewer. The data for Intercast was embedded in the Vertical Blanking Interval (VBI) of the video signal carrying the Intercast-enabled program, at a maximum of 10.5 Kilobytes/sec in 10 of the 45 lines of the VBI.
World System Teletext (WST) is the name of a standard for encoding and displaying teletext information, which is used as the standard for teletext throughout Europe today. It was adopted into the international standard CCIR 653 of 1986 as CCIR Teletext System B.
Norpak Corporation was a company headquartered in Kanata, Ontario, Canada, that specialized in the development of systems for television-based data transmission. In 2010, it was acquired by Ross Video Limited of Iroquois and Ottawa, Ontario.
References
↑ Kawamoto, Kevin (2003). Digital Journalism: Emerging Media and the Changing Horizons of Journalism. Rowman & Littlefield. p.32. ISBN074252681X.
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