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A British Teletext Ltd. index page from September 2001, showing news about the September 11 attacks

Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipped television sets.[1][2] Teletext sends data in the broadcast signal, hidden in the invisible vertical blanking interval (VBI) area at the top and bottom of the screen.[3] 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. Teletext was uni-directional- the user could only receive, and not respond or send data of their own.[4][5]

Teletext was created in the United Kingdom in the early 1970s by John Adams, Philips' lead designer for video display units to provide closed captioning to television shows for the hearing impaired.[6] Public teletext information services were introduced by major broadcasters in the UK,[7] starting with the BBC's Ceefax service in 1974.[8] It offered a range of text-based information, typically including news, weather and TV schedules. Similar systems were subsequently introduced by other television broadcasters in the UK and mainland Europe in the following years.

Teletext inspired the later Videotex system that enabled bi-directional communication in a format later recognised as a prototype of the world wide web. Implementations included the French Minitel and Prestel, introduced by the UK's General Post Office. Prestel used Teletext's display standards but instead ran over bi-directional telephone lines using modems.[9]

Teletext formed the basis for the World System Teletext standard (CCIR Teletext System B), an extended version of the original system.[10] This standard saw widespread use across Europe[11][12][13] starting in the 1980s, with almost all television sets including a decoder. Other standards were developed around the world, notably NABTS (CCIR Teletext System C) in the United States,[14] Antiope (CCIR Teletext System A) in France[15] and JTES (CCIR Teletext System D) in Japan,[16] but these were never as popular as their European counterpart and most closed by the early 1990s.

Most European teletext services continued to exist in one form or another until well into the 2000s when the expansion of the Internet precipitated a closure of some of them. However, many European television stations continue to provide teletext services and even make teletext content available via web and dedicated apps.[17][18]

The recent availability of digital television has led to more advanced systems being provided that perform the same task, such as MHEG-5 in the UK, and Multimedia Home Platform.

History

[edit]
Early Ceefax test in 1972
Prestel page from 1981

Teletext is a means of sending text and simple geometric shapes to a properly equipped television screen by use of one of the "vertical blanking interval" lines that together form the dark band dividing pictures horizontally on the television screen.[19][20] Transmitting and displaying subtitles was relatively easy. It requires limited bandwidth; at a rate of perhaps a few words per second. However, it was found that by combining even a slow data rate with a suitable memory, whole pages of information could be sent and stored on the TV for later recall.

In the early 1970s, work was in progress in Britain to develop such a system. The goal was to provide UK rural homes with electronic hardware that could download pages of up-to-date news, reports, facts and figures targeting UK agriculture. The original idea was the brainchild of Philips (CAL) Laboratories in 1970.

In 1971, CAL engineer John Adams created a design and proposal for UK broadcasters. His configuration contained all the fundamental elements of classic teletext including pages of 24 rows with 40 characters each, page selection, sub-pages of information and vertical blanking interval data transmission.[21] A major objective for Adams during the concept development stage was to make teletext affordable to the home user. In reality, there was no scope to make an economic teletext system with 1971 technology. However, as the low cost was essential to the project's long-term success, this obstacle had to be overcome.

Meanwhile, the General Post Office (GPO), whose telecommunications division later became British Telecom, had been researching a similar concept since the late 1960s, known as Viewdata. Unlike Teledata, a one-way service carried in the existing TV signal, Viewdata was a two-way system using telephones.[22] Since the Post Office owned the telephones, this was considered to be an excellent way to drive more customers to use the phones.

In 1972, the BBC demonstrated its system, now known as Ceefax ("seeing facts", the departmental stationery used the "Cx" logo), on various news shows.[23] The Independent Television Authority (ITA) announced its own service in 1973, known as ORACLE (Optional Reception of Announcements by Coded Line Electronics). Not to be outdone, the GPO immediately announced a 1200/75 baud videotext service under the name Prestel (this system was based on teletext protocols, but telephone-based).

The TV-broadcast based systems were originally incompatible; Ceefax displayed pages of 24 lines with 32 characters each, while ORACLE offered pages of 22 lines with 40 characters each. In other ways the standards overlapped; for instance, both used 7-bit ASCII characters and other basic details. In 1974, all the services agreed on a standard for displaying the information. The display would be a simple 24 × 40 grid of text, with some graphics characters for constructing simple graphics. The standard did not define the delivery system, so both Viewdata-like and Teledata-like services could at least share the TV-side hardware (which at that time was quite expensive).

Rollout in the United Kingdom

[edit]

Following test transmissions in 1973–74, towards the end of 1974 the BBC news department put together an editorial team of nine, including and led by editor Colin McIntyre, to develop a news and information service. Initially limited to 30 pages, the Ceefax service was later expanded to 100 pages and was launched formally in 1976.[1]

Wireless World magazine ran a series of articles between November 1975 and June 1976 describing the design and construction of a teletext decoder using mainly TTL devices; however, development was limited until the first TV sets with built-in decoders started appearing in 1977.

The "Broadcast Teletext Specification" was published in September 1976 jointly by the IBA, the BBC and the British Radio Equipment Manufacturers' Association.[7] The new standard also made the term "teletext" generic, describing any such system. The standard was internationalised as World System Teletext (WST) by CCIR.

Other systems entered commercial service, like ORACLE (first broadcast on the ITV network in 1978) and Prestel (in 1979).

Teletext became popular in the United Kingdom when Ceefax, Oracle and the British government promoted teletext through a massive campaign in 1981.[24]

By 1982, there were two million such sets, and by the mid-1980s they were available as an option for almost every European TV set, typically by means of a plug-in circuit board. It took another decade before the decoders became a standard feature on almost all sets with a screen size above 15 inches (Teletext is still usually only an option for smaller "portable" sets). From the mid-1980s, both Ceefax and ORACLE were broadcasting several hundred pages on every channel, slowly changing them throughout the day.

In 1986, WST was formalised as an international standard as CCIR Teletext System B. It was also adopted in many other European countries.

Development in other countries

[edit]
Main article: List of teletext services
Teletext launch in Amsterdam, 1980
May 2020 teletext page 100 of German public broadcaster ARD

Besides the US and UK developments, a number of similar teletext services were developed in other countries, some of which attempted to address the limitations of the initial British-developed system, by adding extended character sets or improving graphic abilities. For example, state-owned RAI launched its teletext service, called Televideo,[25] in 1984, with support for Latin character set. Mediaset, the main commercial broadcaster, launched its Mediavideo Teletext in 1993. La7Video in 2001, heir to TMCvideo, the teletext of TMC Telemontecarlo born in the mids 90s. Always in the 90s, Rete A and Rete Mia teletexts arrived. Retemia's teletext has not been functional since 2000, Rete A's since 2006, La7Video since 2014 and Mediavideo since 2022. These developments are covered by the different World System Teletext Levels.

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 World System Teletext in 1991.

In North America, NABTS, the North American Broadcast Teletext Specification, was developed to encoding NAPLPS teletext pages, as well as other types of digital data. NABTS was the standard used for both CBS's ExtraVision and NBC's NBC Teletext services in the mid-1980s.

Japan developed its own JTES[16] teletext system with support for Chinese, Katakana and Hiragana characters. Broadcasts started in 1983 by NHK.[26][27]

In 1986, the four existing teletext systems were adopted into the international standard CCIR 653 (now ITU-R BT.653) as CCIR Teletext System A (Antiope), B (World System Teletext), C (NABTS) and D (JTES).[10]

In 2023, the Dutch public broadcasting organization NOS replaced the original underlying system for teletext that had been in use since the 1980s with a new system.[28] The reason behind the replacement was that the original Cyclone system became harder to maintain over the years and the NOS even had to consult sometimes retired British teletext experts to deal with issues.[29] For example, a recent issue was that a Windows update was incompatible with the old Cyclone system.[30][28] Since NOS Teletekst is still popular in the Netherlands (with 3.5 million people using it weekly on televisions and 1 million people using it weekly as app on other devices), NOS decided to build a new modern underlying system to replace Cyclone.[31][30] To make Teletekst look visually the same as on the old Cyclone system, the developers of the new system made use of reverse engineering.[28][32]

Teletext systems used in various countries/geographical areas in 1998[10]
Country/geographical area Teletext standard Remarks
Australia B
Belgium A, B
Brazil C (modified)
Canada C
China B Extended character set with Chinese characters
Colombia A
Denmark B
Finland B
France A
Germany B
India A
Ireland B RTÉ Aertel launched in 1987 on RTE 1 and 2. Other services on launched later on TV3 and TG4
Italy B
Japan D
Malaysia B
Netherlands B
New Zealand B
Norway B
Poland B Experimental
Singapore B
South Africa B Character set with variations to also accommodate Afrikaans
Spain B Character set with variations to accommodate Basque, Catalan and Galician
Sweden B
Turkey B Character set with variations to accommodate Turkish
Ukraine B
United Kingdom B
United States C
Yugoslavia B Extended character set

Decline

[edit]

The World Wide Web began to take over some of the functions of teletext from the late 1990s. However, due to its broadcast nature, Teletext remained a reliable source of information during times of crisis, for example during the September 11 attacks when webpages of major news sites became inaccessible because of the high demand.[33]

As the web matured, many broadcasters ceased broadcast of Teletext — CNN in 2006 and the BBC in 2012. In the UK the decline of Teletext was hastened by the introduction of digital television, though an aspect of teletext continues in closed captioning. In other countries the system is still widely used on standard-definition DVB broadcasts.

A number of broadcast authorities have ceased the transmission of teletext services.

  • International broadcasters: A live teletext is no longer available on CNN International.[34] Although many pages are still available, they have not been updated since 31 October 2006.
  • United Kingdom: the founder of the world's first teletext service, the BBC, closed its Ceefax service in 2012 when Britain adopted a fully digital television broadcast system. The BBC maintains a Red Button service on digital TV which includes access to the latest text news; that text news service is accessible on the BBC News Channel and during BBC One newscasts. Plans to shut it down in 2020 were changed and a reduced service is planned into 2021.[35][needs update] Many channels on Sky still[when?] broadcast teletext subtitles and may still have a small number of active pages.[36] Analogue teletext ended in each region after analog broadcasts finished: see Digital switchover dates in the United Kingdom.
  • Australia: the Seven Network shut down the Austext service on 30 September 2009. They said that the technology has come to the end of its useful service life and is not commercially viable to replace.
  • New Zealand: TVNZ Access Services announced the discontinuation of the service on April 2, 2013. A claim about equipment failures and that web sites have been used instead has been given as the reason.[37]
  • Ireland: In November 2019, it was announced that RTÉ's Aertel would be shut down as part of cost-cutting measures.[38][39] On 2 October 2023, it was announced by RTÉ that the service would be shut down on 12 October 2023.[40]
  • Italy: Some nation-wide teletext services were switched off; for example, MTV Video was active between 2000 and 2010, while "LA7 Video", the teletext service of La7, was launched in 2001 but discontinued in 2014.
  • Malaysia: RTM1 and 2 ceased transmission of teletext on 1 January 2000. Media Prima reduced the amount of content offered on the Infonet teletext service on TV 3 at the same time, and finally shut off the service for good on the first of January 2008.
  • Singapore: MediaCorp discontinued its teletext service on 30 September 2013.[41]

Subtitling still continues to use teletext in Australia, New Zealand, and Singapore with some providers switching to using image-based DVB subtitling for HD broadcasts. New Zealand solely uses DVB subtitling on terrestrial transmissions despite teletext still being used on internal SDI links.

Technology

[edit]
Exurb cut-out of VBI space of Teletext data from a 4fsc sampled vhs tape.

Teletext information is broadcast in the vertical blanking interval between image frames in a broadcast television signal, in numbered "pages". For example, a list of news headlines might appear on page 110; a teletext user would type "110" into the TV's remote control to view this page. The broadcaster constantly sends out pages in a sequence. There will typically be a delay of a few seconds from requesting the page and it being broadcast and displayed, the time being entirely dependent on the number of pages being broadcast. More sophisticated receivers use a memory buffer to store some or all of the teletext pages as they are broadcast, allowing almost instant display from the buffer. This basic architecture separates teletext from other digital information systems, such as the Internet, whereby pages are 'requested' and then 'sent' to the user – a method not possible given the one-way nature of broadcast teletext. Unlike the Internet, teletext is broadcast, so it does not slow down further as the number of users increases, although the greater number of pages, the longer one is likely to wait for each to be found in the cycle. For this reason, some pages (e.g. common index pages) are broadcast more than once in each cycle.

Teletext is also used for carrying special packets interpreted by TVs and video recorders, containing information about subjects such as channels and programming.[citation needed]

Teletext allows up to eight 'magazines' to be broadcast, identified by the first digit of the three-digit page number (1–8). Within each magazine there may theoretically be up to 256 pages at a given time, numbered in hexadecimal and prefixed with the magazine number – for example, magazine 2 may contain pages numbered 200-2FF. In practice, however, non-decimal page numbers are rarely used as domestic teletext receivers will not have options to select hex values A-F, with such numbered pages only occasionally used for 'special' pages of interest to the broadcaster and not intended for public view.

The broadcaster constantly sends out pages in sequence in one of two modes: Serial mode broadcasts every page sequentially whilst parallel mode divides VBI lines amongst the magazines, enabling one page from each magazine to be broadcast simultaneously. There will typically be a delay of a few seconds from requesting the page and it being broadcast and displayed; the time is entirely dependent on the number of pages being broadcast in the magazine (parallel mode) or in total (serial mode) and the number of VBI lines allocated. In parallel mode, therefore, some magazines will load faster than others.

Data transmission

[edit]
Visual raster of a decoded signal frame extract from a vhs tape, showing the vertical blanking area with white contrasting signal data teletxt.
4fsc sampled VHS PAL signal frame (Luma) produced from an FM RF archive decoded via vhs-decode in 2022 with Teletext in the VBI space above the active picture area.

A standard PAL signal contains 625 lines of video data per screen, broken into two "fields" containing half the lines of the whole image, divided as every odd line, then every even line number. Lines near the top of the screen are used to synchronize the display to the signal and are not seen on-screen. Data formatted in accordance with CEPT presentation layer protocol and data syntax standard is stored in these lines, where they are not visible, using lines 6–22 on the first field and 318–335 on the second field. The system does not have to use all of these lines; a unique pattern of bits allows the decoder to identify which lines contain data. Unused lines must not be used for other services as it will prevent teletext transmission. Some teletext services use a great number of lines, others, for reasons of bandwidth and technical issues, use fewer.

Teletext in the PAL B system can use the VBI lines 6–22 in first half image and 318–334 in the other[42] to transmit 360 data bits including clock run-in and framing code during the active video period at a rate of 6.9375 Mbit/s ±25 bit/s[42] using binary NRZ line coding.[43][42]: 15  The amplitude for a "0" is black level ±2% and a "1" is 66±6% of the difference between black and peak white level.[42] The clock run in consist of 8 times of "10" and the framing code is "11100100".[42] The two last bits of the clock-run in shall start within 12+0.4
−1.0 μs from the negative flank of the line synchronization pulse.[42]: 16 

The 6.9375 Mbit/s rate is 444 × nominal fH, i.e. the TV line frequency.[42] Thus 625 × 25 × 444 = 6,937,500 Hz. Each bit will then be 144 ns long. The bandwidth amplitude is 50% at 3.5 MHz and 0% at 6 MHz.[42] If the horizontal sync pulse during the vertical synchronization starts in the middle of the horizontal scan line. Then first interlace frame will be sent, otherwise, if vertical synchronization let the full video line complete the second interlace frame is sent.[42]: 14 

Like EIA-608, bits are transmitted in the order of LSB to MSB with odd parity coding of 7-bit character codes.[42]: 17  However unlike EIA-608, the DVB version is transmitted the same way. For single bit error recovery during transmission, the packet address (page row and magazine numbers) and header bytes (page number, subtitle flag, etc.) use hamming code 8/4[42]: 21  with extended packets (header extensions) using hamming 24/18,[42]: 21  which basically doubles the bits used.[42]

The commonly used standard B uses a fixed PAL subtitling bandwidth of 8,600 (7,680 without page/packet header) bits/s per field for a maximum of 32 characters per line per caption (maximum three captions – lines 19 – 21) for a 25 frame broadcast. While the bandwidth is greater than EIA-608, so is the error rate with more bits encoded per field. Subtitling packets use a lot of non-boxed spacing to control the horizontal positioning of a caption and to pad out the fixed packet. The vertical caption position is determined by the packet address.

Teletext binary NRZ encodings[43][10]
Standard Color
system		 Informational
CVBS Lines		 Bit rate
[Mbit/s]		 Waveform Bits per line
(including run-in)		 Max. characters
(per page row)
A (Antiope) SECAM 7–18 6.203 Squared Sine wave 320 97
B (World System Teletext) NTSC 10–18 5.727 Symmetrical about 1/2 bit rate 296 32
PAL 7–18 6.938 Symmetrical about 1/2 bit rate 360 40
C (NABTS) NTSC 10–18 5.727 Raised cosine 100% roll-off 288 31
PAL-M 5.734
D (JTES[16][27]) NTSC 10–18 5.727 Controlled cosine roll-off of 0.6 296 32
PAL-M 5.642 100% cosine roll-off

In the case of the Ceefax and ORACLE systems and their successors in the UK, the teletext signal is transmitted as part of the ordinary analog TV signal but concealed from view in the Vertical Blanking Interval (VBI) television lines which do not carry picture information. The teletext signal is digitally coded as 45-byte packets, so the resulting rate is 7,175 bits per second per line (41 7-bit 'bytes' per line, on each of 25 frames per second).

A teletext page comprises one or more frames, each containing a screen-full of text. The pages are sent out one after the other in a continual loop. When the user requests a particular page the decoder simply waits for it to be sent, and then captures it for display. In order to keep the delays reasonably short, services typically only transmit a few hundred frames in total. Even with this limited number, waits can be up to 30 seconds, although teletext broadcasters can control the speed and priority with which various pages are broadcast.

Modern television sets, however, usually have built-in memory, often for a few thousand different pages. This way, the teletext decoder captures every page sent out and stores it in memory, so when a page is requested by the user it can be loaded directly from memory instead of having to wait for the page to be transmitted. When the page is transmitted again, the decoder updates the page in memory.

The text can be displayed instead of the television image, or superimposed on it (a mode commonly called mix). Some pages, such as subtitles (closed captioning), are in-vision, meaning that text is displayed in a block on the screen covering part of the television image.

The original standard provides a monospaced 40×24 character grid. Characters are sent using a 7-bit codec, with an 8th bit employed for error detection.[4] The standard was improved in 1976 (World System Teletext Level 1) to allow for improved appearance and the ability to individually select the color of each character from a palette of eight. The proposed higher resolution Level 2 (1981) was not adopted in Britain (in-vision services from Ceefax & ORACLE did use it at various times, however, though even this was ceased by the BBC in 1996), although transmission rates were doubled from two to four lines a frame.

Levels

[edit]
Comparison between teletext Level 1.0 and teletext Level 2.5
Main article: World System Teletext § Levels

In the early 1980s, a number of higher extension levels were envisaged for the specification, based on ideas then being promoted for worldwide videotex standards (telephone dial-up services offering a similar mix of text and graphics).

The most common implementation is Level 1.5, which supports languages other than English. Virtually any TV sold in Europe since the 1990s has support for this level. After 1994 some stations adopted Level 2.5 Teletext or Hi-Text, which allows for a larger color palette and higher resolution graphics.[2]

The proposed higher content levels included geometrically specified graphics (Level 4), and higher-resolution photographic-type images (Level 5), to be conveyed using the same underlying mechanism at the transport layer. No TV sets currently implement the two most sophisticated levels.[44][45]

Decoders

[edit]

The Mullard SAA5050 was a character generator chip used in the UK teletext-equipped television sets. In addition to the UK version, several variants of the chip existed with slightly different character sets for particular localizations and/or languages. These had part numbers SAA5051 (German), SAA5052 (Swedish), SAA5053 (Italian), SAA5054 (Belgian), SAA5055 (U.S. ASCII), SAA5056 (Hebrew) and SAA5057 (Cyrillic). The type of decoder circuitry is sometimes marked on televisions as CCT (Computer-Controlled Teletext), or ECCT (Enhanced Computer-Controlled Teletext).

Besides the hardware implementations, it is also possible to decode teletext using a PC and video capture or DVB board,[46] as well as recover historical teletext from self-recorded VHS tapes.[47]

The Acorn BBC Micro's default graphics mode (mode 7) was based on teletext display, and the computer could be used to create and serve teletext-style pages over a modem connection. With a suitable adapter, the computer could receive and display teletext pages, as well as software over the BBC's Ceefax service, for a time. The Philips P2000 home computer's video logic was also based on a chip designed to provide teletext services on television sets.[48]

Uses

[edit]

Interactive teletext

[edit]

Some TV channels offer a service called interactive teletext to remedy some of the shortcomings of standard teletext. To use interactive teletext, the user calls a special telephone number with a push-button telephone. A computer then instructs them to go to a teletext page which is assigned to them for that session.

Usually, the page initially contains a menu of options, from which the user chooses using the telephone keypad. When a choice has been made, the selected page is immediately broadcast for viewing. This is in contrast with usual teletext where the user has to wait for the selected page to be broadcast.

This technology enables teletext to be used for games, chat, access to databases, etc. It overcomes the limitations on the number of available pages. On the other hand, only a limited number of users can be serviced at the same time, since one page number is allocated per user. Some channels solve this by taking into account where the user is calling from and by broadcasting different teletext pages in different geographical regions. In that way, two different users can be assigned the same page number at the same time as long as they do not receive the TV signals from the same source. Another drawback to the technology is the privacy concerns in that many users can see what a user is doing because the interactive pages are received by all viewers. Also, the user usually has to pay for the telephone call to the TV station.

Bulletin boards

[edit]

Spanish prisons have banned or deactivated TV sets with teletext capabilities, after finding that the inmates received coded messages from accomplices outside through the bulletin board sections.[49] The same phenomenon has been observed in Finland, where inmates received messages from smugglers through the family bulletin board.[50] [51]

Teletext art

[edit]
Teletext artworks by TeleNFT (2022) in the typical aesthetics.

The ability to display colored characters and pixels is also used to create teletext art. A teletext page in World System Teletext Level 1 format offers 7-bit colors and a canvas with 40x24 sixels, each containing a text character or 2x3 pixels. Specific control commands can be used to switch between text and graphic pixels, and to add effects such as rasterization, blinking, or double line height. The rasterized working area and the limited display options result in the typical teletext aesthetics.[52]

In cooperation with Finnish state television YLE, the Museum of Teletext Art[53] has been presenting and archiving international teletext art online, on air and in exhibitions since 2014.[54]

Legacy and successors

[edit]

While the basic teletext format has remained unchanged in more than 30 years, a number of improvements and additions have been made.

  • Standard electronic program guide (EPGs), like NexTView, are based on teletext, using a compact binary format instead of preformatted text pages.
  • Various other kinds of information are sent over the teletext protocol. For instance, Programme Delivery Control (PDC) signals—used by video recorders for starting/stopping recording at the correct time even during changes in programming—are sent as Teletext packets. A similar, but different, standard Video Programming System is also used for this purpose.
  • Teletext pages may contain special packages allowing VCRs to interpret their contents. This is used in relation to the Video Programming by Teletext (also known as startext) system which allows users to program their videos for recording by simply selecting the program on a teletext page with a listing of programs.
  • Other standards define how special teletext packets may contain information about the name of the channel and the program currently being shown.[citation needed]

Internet services

[edit]

Prestel was a British information-retrieval system based on teletext protocols. However, it was essentially a different system, using a modem and the phone system to transmit and receive the data, comparable to systems such as France's Minitel. The modem was asymmetric, with data sent at 75-bit/s, and received at 1200-bit/s. This two-way nature allowed pages to be served on request, in contrast to the TV-based systems' sequential rolling method. It also meant that a limited number of extra services were available such as booking events or train tickets and a limited amount of online banking.

A number of teletext services have been syndicated to web viewers,[18] which mimic the look and feel of broadcast teletext. RSS feeds of news and information from the BBC are presented in Ceefax format in the web viewer.[17]

In 2016, the Teefax teletext service was launched in the United Kingdom to coverage by the BBC,[55] ITV[56] and others. Using a Raspberry Pi computer card as a set-top box, it feeds its service to standard televisions. Teefax content is a mix of crowdsourcing, syndication and contributions from media professionals who contributed heavily to broadcast teletext services. Teefax is also syndicated to a web viewer.[57]

Digital teletext

[edit]
NRK digital teletext

With the advent of digital television, some countries adopted the name "digital teletext" for newer standards, despite the older teletext standards' digital nature. Digital teletext is encoded with standards including MHEG-5 and Multimedia Home Platform (MHP).

Other countries use the same teletext streams as before on DVB transmissions, due to the DVB-TXT and DVB-VBI sub-standards. Those allow the emulation of analogue teletext on digital TV platforms, directly on the TV or set-top box, or by recreating analog output, reproducing the vertical blanking interval data in which teletext is carried.

Similar systems

[edit]

A closely related service is the Video Program System (VPS), introduced in Germany in 1985. Like teletext, this signal is also broadcast in the vertical blanking interval. It consists only of 32 bits of data, primarily the date and time for which the broadcast of the currently running TV programme was originally scheduled. Video recorders can use this information (instead of a simple timer) in order to automatically record a scheduled programme, even if the broadcast time changes after the user programmes the VCR. VPS also provides a PAUSE code; broadcasters can use it to mark interruptions and pause the recorders, however, advertisement-financed broadcasters tend not to use it during their ad breaks. VPS (line 16) definition is now included in the Programme Delivery Control (PDC) standard from ETSI.

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Teletext

View on Grokipedia
from Grokipedia
Teletext is a technology for delivering text-based information and simple graphics to television viewers through the unused vertical blanking interval (VBI) lines of signals, allowing users to access pages of , , sports, and other data using a decoder and . This one-way broadcast system multiplexes data packets into specific TV lines (typically 6-22 and 318-335), using a of 6.9375 Mbit/s, to transmit pages structured with 24 rows of 40 characters each at its basic Level 1, enabling cyclic display every 20-30 seconds without interrupting the main video signal. Developed in the during the early 1970s, Teletext originated from efforts by the and (IBA) to provide accessible information services, with foundational work by Philips engineer , who built the first prototype in 1971 featuring 24 rows of 40 characters and page selection capabilities. The began test transmissions in 1973, launching its service publicly on September 23, 1974, initially with subtitles for the deaf and expanding to 30 pages of information by 1975, while the IBA introduced the competing service in 1978. By 1976, the , IBA, and British Radio Equipment Manufacturers' Association established the initial British Teletext standard, which evolved into the international (WST) formalized as CCIR Recommendation 653 (System B) in 1986, supporting enhanced features like re-definable characters, color graphics, and multi-language sets across Levels 1.5, 2.5, and 3.5. Teletext saw widespread adoption in , where it became a staple for free, real-time information delivery, reaching a peak of approximately 22 million weekly users in the UK during the through affordable decoder rentals and integrations into TVs. Globally, WST influenced systems in at least 15 countries as of 2024, including adaptations in (e.g., Japan's with enhanced error correction) and limited trials in , though it never gained traction there due to competing standards like NAPLPS. Innovations like telesoftware, proposed in 1977 and implemented in the 1980s for downloading basic programs to computers such as the , extended its utility beyond static pages. The service declined with the shift to , ending for ITV and in 2009 and for in October 2012 after 38 years, though it persists in regions without full digital transitions.

History

Invention and Early Development

The development of Teletext originated from a 1971 proposal by engineer , who built the first prototype featuring 24 rows of 40 characters and page selection capabilities, influencing the 's adoption. At the 's research facilities in the , engineers Geoff Larkby and Barry Pyatt, working in the Designs Department (Television Group), experimented with an analogue text transmission system that embedded data in the vertical blanking interval of the 625-line PAL television standard since the late 1960s. This approach leveraged spare scanning lines—specifically lines 7 to 22 in the first field and lines 320 to 335 in the second field—to broadcast low-bandwidth text without interfering with the video image, addressing the need for accessible information in an era before widespread digital alternatives. By the early 1970s, these experiments evolved into a more structured prototype known as (a portmanteau of "see facts"), with the BBC filing a for the "Teledata" system in February 1972. Initial testing involved manual page creation using punch tape and encoding machines, overseen by founding editor Colin , who produced content single-handedly during this phase. An experimental field trial commenced on 16 July 1973 on BBC-2, transmitting a limited set of pages via UHF signals to demonstrate the feasibility of on-demand text delivery, such as summaries and updates. This prototype highlighted Teletext's potential as a broadcast extension, transmitting data cyclically in the signal's non-visible intervals to enable user selection via simple decoders. Parallel inventions emerged around the same period, reflecting broader European interest in broadcast data services. In the UK, the Independent Television Authority announced its (Optional Reception of Announcements by Coded Line Electronics) system in 1973, developed between 1972 and as a text-only service compatible with standards, with public demonstrations that year. In , the Antiope system—designed for both teletext and applications—was under development in the early by the Centre Commun d'Études de Télédiffusion et Télécommunications, achieving initial field trials in 1975 using the standard's equivalent line allocations. These efforts culminated in 's public launch on 23 September , marking the world's first operational teletext service with 30 initial pages.

Rollout in the United Kingdom

The rollout of Teletext in the United Kingdom commenced with the BBC's Ceefax service, which began public transmissions on 23 September 1974 as an experimental offering with 30 pages of information covering news, weather, and sports. Initially limited to viewers with adapted televisions, Ceefax transitioned to a full regular service by 1977, broadcasting seven days a week and expanding its content to include subtitles for the deaf. The Independent Television (ITV) network introduced its competing Oracle service in 1978, focusing on commercial content such as advertisements and classifieds alongside news and entertainment pages. Regulatory standardization accelerated the service's development when the Independent Broadcasting Authority (IBA), in collaboration with the and the British Radio Equipment Manufacturers' Association (BREMA), published the Broadcast Teletext Specification in September 1976. This document defined key parameters for data transmission, page formatting, and compatibility, ensuring interoperability across broadcasters. It laid the foundation for the (WST), which was adopted in the UK that same year as the national standard for Teletext broadcasting. Adoption grew steadily through the , driven by falling prices for equipped televisions and government promotion; household penetration rose from 2% in to 19% by , equating to millions of users accessing services daily. Integration with video recorders enabled off-air capture of Teletext signals embedded in the vertical blanking interval, allowing viewers to record and review pages at leisure—a feature particularly useful for time-sensitive content like . Service providers proliferated with Channel 4's launch on 2 November 1982, which adopted the system and added pages on education, , and minority interests. Page counts expanded significantly to meet demand: grew from its initial 30 pages to 400 by and over 800 by 1983, while Oracle followed a similar trajectory, reaching hundreds of pages with regional variations.

International Adoption and Variations

Teletext, originating as the UK's and systems in the , served as the foundational model for international adaptations, building on the standard established in 1976, which formed the basis for the international (WST) standardized in 1986. In the , one of the earliest adopters, the (NOS) launched a teletext service in the late under the banner of "Tijd voor Televisie," featuring news and public information delivered via PAL broadcasts, which influenced neighboring regions like in . Germany introduced teletext in 1977 through public broadcasters ARD and , initially demonstrated at the International Radio and (IFA); while often conflated with the separate service Bildschirmtext launched in 1983, German teletext focused on broadcast delivery of news and services using WST-compatible formats. In , the Antiope system debuted in 1972, developed by the Centre Commun d'Études de Télédiffusion et Télécommunications (CCETT), and was adapted for television standards by 1980, later integrating with the two-way network to provide enhanced interactive features alongside one-way teletext content like news and directories. Japan developed its own broadcast teletext system, JTES, in the 1980s, alongside the telephone-based CAPTAIN system announced by (NTT) in 1978 and trialed from 1979 to 1981. Regional variations deviated from the core WST framework to accommodate local needs, such as France's Antiope, which emphasized higher-resolution and compatibility with Minitel's alphanumeric protocols. In , the 1980s saw the development of non-WST standards like the North American Broadcast Teletext Specification (NABTS), introduced in to enable fast navigation features akin to Europe's FastText, though implementations remained fragmented. and coding also varied; while WST employed 8-bit codes for broader character support, some early systems relied on 7-bit ASCII derivatives, limiting compatibility in multilingual environments. By the 1990s, teletext achieved widespread penetration in , with public broadcasters driving adoption; in , usage reached approximately 90% of households in countries like and , where services provided essential news and subtitling. In contrast, North American rollout was constrained, with limited services on select networks due to the standard's incompatibility with European PAL-based designs, resulting in slower decoder integration and lower overall uptake. Key challenges included adapting to diverse broadcast standards, as PAL's 625-line format allowed higher data rates than NTSC's 525 lines, necessitating adjustments to clock rates and error correction for reliable transmission. Language support posed further hurdles, particularly in WST Level 1, which initially offered only basic Latin characters, complicating accented or non-Roman scripts in regions like France and Scandinavia until Level 1.5 enhancements in the 1980s expanded the repertoire to include diacritics and Cyrillic elements.

Decline and Phase-Out

The decline of Teletext began in the late , primarily driven by the rapid expansion of the , which offered more interactive, multimedia-rich information services compared to Teletext's static text pages. Cable and platforms, which proliferated during this period, often bypassed analog Teletext signals entirely, as they relied on digital transmission methods incompatible with the original broadcast standard. These factors reduced Teletext's accessibility and relevance for new viewers, shifting audiences toward online alternatives for , , and schedules. The transition to accelerated Teletext's obsolescence, as analog broadcasts—essential for traditional Teletext—were phased out worldwide. In the , the digital switchover (DSO) occurred between 2008 and 2012, culminating in the permanent shutdown of analog signals and the end of services like BBC's and ITV's Teletext on 23 October 2012. Similarly, in the , commercial broadcaster discontinued its RTL Text service on 1 2017, citing low usage amid digital alternatives, though the public NOS Teletekst persists as of 2025 with modernized systems. In , shutdowns have been more gradual, with services like Poland's Telegazeta on remaining operational into the 2020s despite political upheavals in . Some analog Teletext pockets endure in developing regions, such as parts of and , where low maintenance costs—requiring minimal infrastructure updates—make it economically viable for broadcasters to sustain basic information services even as of 2025. At its peak in the early , UK Teletext services like reached approximately 22 million weekly users, delivering millions of page views daily for news and entertainment. By the 2000s, however, usage had dwindled to a niche , particularly among older demographics in rural areas without reliable , as penetration surpassed 50% in many developed markets.

Technical Principles

Data Transmission and Signal Integration

Teletext data is transmitted within the vertical blanking interval (VBI) of signals, specifically utilizing lines 6 through 22 (and optionally lines 318 through 335) in 625-line systems such as PAL and . This placement ensures that the data occupies non-visible portions of the broadcast signal, avoiding interference with the displayed video image. The transmission occurs as non-vision data bursts modulated at a subcarrier frequency of approximately 6.9375 MHz, which is 444 times the nominal line frequency of 15.625 kHz, allowing for high-speed digital embedding without affecting the or components of the video. The rate for Teletext transmission is 6.9375 Mbit/s (±25 parts per million), enabling the delivery of up to 360 bits per VBI line in a structured packet format. Each packet consists of a clock run-in (a 16-bit alternating pattern for bit ), followed by an 8-bit framing code (binary 11100100), a identifier formed by the packet (magazine and packet number), and 42 bytes (336 bits) with additional parity, for a total of 360 bits per packet. This structure supports sequential broadcasting of pages, with each line in the VBI dedicated to a single packet, allowing for efficient of multiple Teletext services within the available lines. across the broadcast is maintained through line identification packets, which specify the and continuity index to align receiver processing with the transmitted stream. Error handling is integral to reliable transmission over noisy broadcast channels, employing a combination of and parity checks. Critical header and addressing bytes use a Hamming 8/4 , which encodes 4 bits with 4 parity bits to detect and correct single-bit errors, ensuring accurate packet identification even in the presence of transmission impairments. The remaining bytes incorporate odd parity bits per byte for basic error detection, providing additional robustness without significantly reducing the effective capacity. This scheme allows Teletext signals to maintain integrity within the analog video environment, where the remains imperceptible to standard television receivers lacking decoding capabilities.

Page Structure and Formatting

Teletext pages are structured as a grid of 40 columns by 25 rows, accommodating 1,000 characters in total, with each page represented by 1,000 bytes of data (40 bytes per row, including 7-bit character codes plus odd parity). This format allows for a fixed display area on television screens, where the first row (row 0) typically serves as a header containing the page address and initial control codes, followed by 24 content rows, and an optional 25th row for additional navigation information. Pages are organized into up to eight magazines, numbered 1 through 8, with each magazine holding pages numbered from 000 to 899 (or up to FFF in hexadecimal for extended use), denoted in the format magazine/page (e.g., 1/001 for the first page in magazine 1). This numbering system enables efficient indexing and retrieval during transmission, where pages are broadcast in data packets grouped by magazine. Character encoding in Teletext employs a 7-bit similar to ASCII, augmented with odd parity for detection, supporting two primary character sets: G0 for 96 alphanumeric characters (including ) and G1 for 128 graphics-oriented symbols, including 64 mosaic blocks. The first 32 codes (0x00 to 0x1F) are reserved for non-printing control functions that modify display attributes, such as selecting foreground and background colors from a palette of eight (, , , , , , , white) or enabling double-height text by doubling the vertical size of subsequent characters or lines. These control codes are embedded within the page and apply sequentially until overridden, allowing dynamic formatting without altering the base character grid. Formatting codes extend the character set to include low-resolution through mosaic characters, where each 6x10 character cell is divided into 2x3 configurable blocks to form patterns, rendered in the selected colors for simple illustrations or borders. Parallel attributes, such as "hold mosaics" (which prevents automatic separation of adjacent blocks) and "release mosaics" (which restores separation for cleaner text transitions), operate alongside color and size controls to refine the visual output, ensuring compatibility with basic decoders while supporting creative layouts. These attributes are activated via specific control codes (e.g., 0x1E for hold mosaics) and maintain state across characters until reset. Navigation within and between pages relies on standardized elements in the top and bottom rows: the top row (row 0) displays a header with the and page number, often abbreviated (e.g., "100" for page 100), providing immediate , while the bottom row (row 24) includes fast-text associated with four colored buttons—red, green, yellow, and —each linking to predefined pages for rapid access to related content like indices or subtopics. These are encoded in dedicated transmission packets and visually cued by color changes in the button labels, enhancing user interactivity on simple remote controls.

Service Levels and Enhancements

Teletext services evolved through standardized presentation levels defined by the European Telecommunications Standards Institute (ETSI), allowing progressive enhancements in display capabilities while maintaining backward compatibility for existing decoders. These levels, from basic text delivery in the to advanced in the late , were signaled through specific enhancement packets in the data stream, enabling higher-level decoders to interpret additional features without disrupting lower-level displays. Level 1 remained the dominant standard throughout Teletext's , with higher levels seeing limited due to hardware constraints and the rise of digital alternatives. Level 1, formalized in the as the foundational standard, provided basic alphanumeric text and rudimentary on a 40-character by 24- or 25-row grid, using a fixed 8-color palette (black, red, green, yellow, blue, magenta, cyan, and white) via Color Look-Up Table (CLUT) 0. It supported G0 and G1 character sets for text, along with G1 block mosaics for simple , all within a 6x10 character cell. No additional enhancements were required, making it fully compatible with all subsequent decoders, and it formed the baseline for all Teletext pages. Level 1.5 extended Level 1 in the early by incorporating supplementary G2 characters and diacritics through packet X/26, expanding support for national and multilingual options while retaining the same 8-color palette and resolution. It introduced smoothed G3 mosaics more reliably but remained optional for enhancements, ensuring compatibility with Level 1 decoders that ignored X/26 packets. This level became a common interim standard before more substantial upgrades. Level 2.5, introduced in the mid-1990s and standardized by ETSI in 1997, significantly enhanced visual capabilities with a 32-color palette (8 fixed colors plus 24 redefinable via CLUTs 2 and 3), support for side-panels extending rows to 56 characters, and Dynamically Redefinable Character Sets (DRCS) in a 12x10x1 mode for custom graphics like logos. It added non-spacing attributes for improved , proportional spacing, and object-based elements (active, adaptive, or passive) for overlaid content, along with smoother mosaics and expanded character repertoires for international use. was achieved through packets like X/28/0 (Format 1) for signaling and X/27/4 for linking enhancements to basic Level 1 content, allowing Level 1 decoders to display core text while ignoring extras. Adoption was limited in , with implementations in by 1998 and trials in and the , but few televisions supported it fully due to manufacturer hesitancy. Level 3.5, also standardized in 1997, built on Level 2.5 with object-based using all DRCS modes (12x10x1, 12x10x2, 12x10x4, and 6x5x4 pixels) for more complex, redefinable elements, and introduced 16-level via DCLUT16 for subtler . It supported fully redefinable colors across CLUTs 0-3, dynamic adjustments, bold and italic styles, and through adaptive objects, with up to 1,200 packets per page for richer content. Signaling occurred via X/28/4 and M/29 packets, ensuring compatibility only with Level 2.5 or higher decoders, as Level 1/1.5 devices could not render these features. Its adoption was rare in the late 1990s, confined to experimental services in parts of amid the shift to , rendering it largely obsolete before widespread use.

Implementation and Hardware

Decoders and External Devices

Teletext decoders emerged as standalone devices in the to enable reception of the service on standard televisions lacking built-in support, primarily functioning as set-top boxes that extracted data from the vertical blanking interval (VBI) of broadcast signals. Early commercial decoders, introduced around , were priced at over £100 and designed for services like ; they utilized integrated circuits to process and decode Teletext signals from RF inputs. These early devices typically featured limited page storage in RAM, ranging from 8 to 100 pages depending on the model, allowing users to cache and quickly access content without constant signal dependency, and output a teletext-only video signal directly to a television via composite or RF modulation. Basic models included a for page navigation and simple display controls, emphasizing reliability in decoding the 625-line PAL signals prevalent in . In the , decoder evolution incorporated integrations with , such as VCRs that supported time-shift recording of Teletext pages for later viewing, exemplified by devices from manufacturers like ITT and that combined decoding with tape-based storage. By the 1990s, external PC cards became available for personal computers, enabling Teletext capture and processing through expansion slots like ISA or PCI, which facilitated data export to software applications for archiving or analysis. Modern external devices remain niche, primarily USB adapters developed post-2010 for enthusiasts preserving legacy analog signals, such as those compatible with or PAL broadcasts, allowing decoding on contemporary computers via software interfaces without requiring full set-top hardware. These adapters, often based on FPGA chips for efficient VBI extraction, cater to archival or hobbyist uses rather than widespread adoption.

Built-in Television Support

The integration of Teletext decoders into televisions marked a significant advancement in the late , as declining costs of silicon chips enabled manufacturers to embed decoding hardware directly into TV sets rather than relying solely on external adapters. Early examples included ITT's Digivision series, which incorporated built-in Teletext capabilities as part of their microprocessor-based systems introduced toward the end of the decade. By the , built-in support had become standard across , with penetration rates exceeding 60% of TV sets in countries like by the mid-1990s and approaching near-universal inclusion in new models as an industry norm. Key to this integration were very-large-scale integration (VLSI) chips designed specifically for Teletext processing. The Mullard SAA5050 series served as a foundational character generator and Level 1 decoder, converting 7-bit Teletext codes into dot-matrix patterns for display on standard television screens, and was widely adopted in and European sets for its support of the 1976 Teletext specification including alphanumeric and . Later implementations incorporated microprocessor-based systems, such as those using the for page storage and buffering, allowing TVs to cache multiple pages for quicker access without constant signal reacquisition. User interfaces for built-in Teletext emphasized simplicity to align with existing TV controls. Remote controls typically featured dedicated buttons for page up/down navigation, numeric keypads for direct three-digit page entry, and hold functions to freeze content, enabling users to browse the sequential magazine-style structure of services like or . Advanced sets in the and added on-screen menus for programming favorite pages, often accessed via a "reveal" or "index" button to uncover hidden or subpages. Despite these features, early built-in Teletext systems had notable limitations that affected usability. Most sets from the 1970s and 1980s supported only basic Level 1 decoding, lacking fast-text functionality—which used colored remote buttons for one-key access to linked subpages and was not widely introduced until the mid-1990s with Level 2.5 enhancements. Regional variations were pronounced; , built-in support remained rare due to limited broadcaster trials, compatibility issues with the standard, and high equipment costs, resulting in negligible consumer adoption beyond experimental phases.

Software and Middleware

Software and middleware for Teletext encompassed a range of tools developed from the onward to facilitate page creation, editing, decoding, and broadcast integration, often leveraging the fixed page structure defined by standards like (WST). In the , the BBC Microcomputer served as a key platform for Teletext page , supported by its display mode and an optional Teletext that enabled users to create and preview pages using built-in or dedicated utilities. The adapter, released around , allowed direct interaction with broadcast services like for downloading and editing content, with its ease of use highlighted in contemporary publications such as the September 1983 issue of The Micro User magazine. Modern open-source authoring tools, such as QTeletextMaker, provide cross-platform editing capabilities using the Qt 6 framework, enabling users to pages compliant with WST specifications and export them in formats like TTI for further processing. Decoding software emerged to extract and display Teletext data on personal computers, including emulators that replicate vintage hardware peripherals for authentic rendering. For instance, SimCoupe emulates the SAM Coupé's Z80-based architecture, supporting its native Teletext decoding routines like those in the MTX ROM for viewing broadcast-style pages. On PCs, Vertical Blanking Interval (VBI) capture via cards such as the Pinnacle MiroVideo DC30, equipped with a Brooktree BT848 chip, allows recording of Teletext streams from analog sources like tapes using Linux-based tools. Software like vhs-teletext processes the captured VBI data through and enhancement steps to recover readable page packets, often achieving high fidelity when using inputs for extraction. Broadcast-side middleware included encoders for inserting Teletext data into video signals, with companies like Snell & Wilcox providing professional solutions integrated into standards conversion workflows. Their KudosPro systems supported (WST) encoding, allowing operators to embed packet data for services like subtitling alongside in SDI environments. Scripting capabilities enabled dynamic page generation, as seen in tools like VBIT2 combined with raspi-teletext, where Python scripts pull content from external sources such as APIs to automate updates and insert time-sensitive information into page headers. These scripts operate within a service loop on devices like , compiling TTI-formatted pages into broadcast streams at rates compatible with PAL/ standards. Archiving efforts in the focused on digitizing legacy Teletext content from analog media, with projects like the Teletext Archaeologist recovering over 1,200 service snapshots from broadcasts spanning to 2018. Initiated around 2018 with a public launch in May 2020, it relies on VBI extraction techniques to preserve pages from sources like and ITV, making them accessible via online viewers while soliciting further tape donations for pre-1990 content.

Applications

Information Broadcasting

Teletext primarily functioned as a one-way broadcast system for delivering static, text-based information to television viewers, enabling access to timely updates without requiring user interaction beyond page selection. Launched in the 1970s, services like the BBC's exemplified this role by transmitting pages embedded in the vertical blanking interval of analog signals, allowing audiences to overlay content on their screens for on-demand viewing of essential information. This passive delivery model positioned Teletext as an accessible "TV newspaper," providing concise summaries that bridged the gap between scheduled broadcasts and print media during an era before widespread . Core services focused on practical, frequently updated content such as news headlines, sports scores, and financial data. News pages offered up-to-the-minute summaries, often drawing from wire services and newsrooms to cover breaking events in 80-word bursts, while sports sections delivered live scores for events like matches and Olympic results. Financial information included share prices and stock quotes, sourced from outlets like the , which were particularly valuable in the for quick market overviews without needing dedicated terminals. These elements were refreshed throughout the day by dedicated editorial teams, ensuring relevance for daily use. Page organization relied on a structured hierarchy within "magazines"—groups of up to 100 pages per channel—to facilitate navigation. Index pages, typically numbered 100 or 200, served as entry points, linking to categories like news (pages 101–199), sports (301–399), and finance (501–599) via color-coded prompts and three-digit codes entered on remote controls. Content cycled continuously, with a full magazine of 100 pages repeating every 22–25 seconds, prioritizing popular indexes for faster access and minimizing wait times for users. In the UK, integrated subtitles as an early information feature starting experimentally in 1975, with the first full subtitled programmes in 1979, overlaying text for programs like broadcasts to enhance accessibility alongside core pages. Across , services like the ' NOS Teletekst, launched in late 1977, provided similar regional tailored to Dutch audiences, including local headlines, weather, and sports results updated in near real-time by a dedicated . At its peak in the 1990s, reached 22 million UK viewers weekly, underscoring Teletext's widespread adoption as a reliable source for everyday information during the 1980s and 1990s.

Interactive Services

Interactive services on Teletext systems enabled limited user engagement through one-way broadcast data combined with external response mechanisms, primarily phone-ins, as the technology lacked built-in . Users navigated pages using remote controls, with enhancements like Fast Text—introduced in the early —allowing quick jumps via colored buttons (red, green, yellow, blue) linked to specific content, streamlining access to interactive elements such as quizzes or response prompts. This navigation was essential for user-initiated features, where viewers selected pages displaying instructions for actions like calling a to participate or book services. Phone-in responses formed the core of Teletext's interactivity, bridging the broadcast medium with telephone networks for actions like voting, quizzes, and bookings. In the UK, services such as Teletext Holidays, which evolved from Oracle's teletext holiday pages starting in the and was formally launched under in 1993, displayed package deals for flights and accommodations, requiring users to phone listed numbers to complete reservations. Similarly, early interactive TV experiments like the BBC's What's Your Story? (1988) prompted viewers to call in plot suggestions for ongoing dramas, integrating audience input into broadcasts. These mechanisms relied on separate phone lines, as Teletext transmitted data unidirectionally via vertical blanking intervals in TV signals, preventing direct device-to-broadcaster feedback. Notable examples included quizzes and basic e-commerce prompts that encouraged phone-based participation. Channel 4's Bamboozle!, launched in 1993 on Teletext pages, featured a multiple-choice game hosted by a virtual character, Bamber Boozler, where users answered questions using Fast Text buttons and phoned in scores for leaderboards or prizes. Limited access to financial information, such as stock prices and banking updates, was available via services like , allowing pre-internet viewers to monitor accounts through displayed data, though transactions required phone confirmation with providers. In the , interactive ads emerged, such as BT's 1996 trial with Walkers Crisps, offering and via Teletext pages to drive phone responses for coupons or entries. Despite these innovations, Teletext's interactive capabilities were constrained by its broadcast-only and dependence on analog phone systems, resulting in delays from page cycling (every 20-25 seconds) and no real-time interaction. Telesoftware extensions, which allowed downloading simple programs for quizzes on compatible decoders, saw low adoption, with only about 31,500 adapters sold by 1989. During the peak, features like games and ads achieved significant viewer engagement, exemplified by Ceefax's 22 million users participating in quizzes and phone-ins, though exact rates varied by service.

Specialized Uses like Subtitling

One of the most prominent specialized applications of Teletext is subtitling, particularly for providing real-time captions to assist viewers with hearing impairments. In the United Kingdom, the British Broadcasting Corporation (BBC) pioneered this use by introducing Teletext-based subtitles starting experimentally in 1975, with the first full subtitled programmes in 1979, marking an early global implementation of broadcast subtitling via teletext. These subtitles are transmitted on dedicated page 888, which cycles rapidly to display text synchronized with the audio and video content. Synchronization is achieved through embedded time codes in the broadcast signal, often derived from the presenter's autocue script for live programming, ensuring captions appear with minimal delay—typically within one to two seconds of spoken dialogue. This integration has been crucial for accessibility, with page 888 becoming a standard feature across UK broadcasters, supporting both pre-recorded and live content. Beyond subtitling, Teletext facilitated other utility-driven services, such as visual weather maps constructed using its mosaic graphics mode. These maps employed block-based characters to render rudimentary symbols for fronts, pressure systems, and temperature zones, allowing viewers to access localized forecasts without full-motion video. For instance, BBC's Ceefax service displayed such mosaics on pages like 401, providing a static yet informative overview updated hourly. Similarly, traffic reports were disseminated via dedicated Teletext pages, offering real-time updates on road conditions, delays, and incidents, often sourced from national transport authorities. In the UK, services like Ceefax included regional traffic summaries, enabling drivers to check conditions before traveling. Teletext also supported emergency communications, particularly for weather-related alerts and public warnings across . Broadcasters utilized priority pages to override standard cycles during crises, such as severe storms or floods, displaying evacuation instructions or safety advisories. In the , this capability aligned with early efforts toward harmonized alert systems, where Teletext pages served as a supplementary channel for disseminating urgent information to equipped households. Technically, these specialized uses relied on reserved page numbers—such as 401 for key updates in some services—and seamless integration with existing broadcast infrastructure, enhancing accessibility for hearing-impaired users through subtitling while extending to broader public safety needs. Globally, variations in subtitling implementation highlighted Teletext's regional focus. While embraced it widely, the United States developed a parallel system using standards, embedded in line 21 of the analog video signal, which provided similar but without Teletext's page-based structure. This separate approach stemmed from differing broadcast norms, with achieving mandated use on major networks by the . By the , Teletext decoders were integrated into over 80% of televisions in many European countries, such as (93% household penetration by 2005) and (near 100% usage among equipped sets), underscoring its entrenched role in specialized services before digital transitions.

Cultural and Social Impact

Teletext Art and Graphics

Teletext art emerged as a creative leveraging the system's rudimentary graphics capabilities, particularly through block characters that allowed users to approximate images in a style akin to during the . These block-based visuals, composed of simple geometric shapes, enabled early enthusiasts to craft illustrations on services like the BBC's , transforming informational pages into makeshift canvases for portraits, logos, and abstract designs. By the 1990s in the UK, teletext magazines such as Mega-Zine on incorporated viewer-submitted artwork, featuring recurring characters like the googly-eyed Davord creature designed by Steve Horsley, which highlighted the medium's potential for humorous and interactive visual storytelling. Artists exploited Teletext's mosaic graphics by treating each character cell as a 2x3 matrix, where combinations of simulated finer details within the 6x10 character height. This approximation technique, part of the standard, allowed for basic and shading, often enhanced through color dithering—alternating adjacent blocks of the limited 8-color palette (including black and transparent) to create illusions of gradients or intermediate hues. Contemporary practitioner Dan Farrimond, for instance, employs these methods to produce satirical pieces like evil clowns and Warhol-inspired bananas, demonstrating how dithering and block placement can evoke within severe constraints. The 2010s saw a revival of Teletext art through cultural events like the International Teletext Art Festival (ITAF), an annual exhibition initiated in by the Finnish collective FixC and hosted on broadcasters such as in and ARD in . By its third edition in 2014, ITAF featured works from 15 international artists, including Juha van Ingen's "" (a pixelated ) and Raquel Meyers' "Thread of Fate" (a text-visual hybrid), broadcast directly via teletext pages to emphasize the medium's broadcast origins. The festival has continued into the 2020s, with the Museum of Teletext Art (MUTA) hosting ongoing exhibitions on teletext pages, including a solo show by Raquel Meyers from June 28, 2025, to January 31, 2026 (pages 805). Preservation efforts have since digitized these artifacts in online archives, such as the Museum of Teletext Art, ensuring access through emulators and static page captures that maintain the original low-resolution fidelity. Teletext's 40-column by 24-row constraint inherently fostered a lo-fi aesthetic, compelling creators to prioritize economy and wit over photorealism, which in turn influenced subcultures like the —where real-time animations using Teletext mosaics pair with soundtracks to produce compact, nostalgic demos. This appeal lies in the medium's imperfections, turning bandwidth limitations into a deliberate artistic choice that echoes the DIY ethos of early digital experimentation.

Online Communities and Bulletin Boards

Teletext services in the and incorporated rudimentary social features through dedicated "letters pages" or message sections, where broadcasters curated and displayed user-submitted content to simulate interactions in a one-way broadcast environment. Users typically submitted messages via postal mail or to editorial teams, who selected, edited, and broadcast them to fit the medium's constraints of short text blocks and cyclic page updates. These features enabled limited public discourse on topics like television programs, , and personal queries, fostering a among viewers without requiring two-way . In the United Kingdom, the BBC's Ceefax service featured a prominent letters page on page 145, which published viewer correspondence to reflect national trends in opinion and interest during the 1980s and 1990s. This page served as an analog precursor to online forums, allowing fans to comment on TV shows, share feedback, and engage indirectly with broadcasters, all under strict moderation to maintain content suitability and brevity. Similarly, ITV's Oracle Teletext included a letters page on page 122, where selected user messages appeared alongside program guides and announcements, often highlighting fan reactions to popular series and events. These moderated sections were central to Oracle's commercial model, blending user input with sponsored content to build viewer loyalty. Beyond broadcaster-led pages, hobbyist communities emerged in the late and , with enthusiasts using modems and personal computers to capture, edit, and exchange Teletext pages via early dial-up connections or floppy disks. Groups of aficionados shared custom , news clippings, and experimental pages, effectively creating informal networks for collaboration outside official broadcasts. For instance, developers and users interfaced Teletext decoders with computers to download full page sets from TV signals, enabling offline archiving and modification that circulated among clubs and early user groups. In subcultures, Teletext's message pages played a role in niche discussions, such as gaming enthusiasts exchanging tips through services like Channel 4's Teletext offerings in the , where short posts hinted at software access and strategies within the era's limited digital landscape. As the proliferated in the mid-, these analog interactions evolved toward digital platforms; Teletext fans mirrored their exchanges on newsgroups dedicated to retro computing and broadcasting , preserving the communal spirit post-shutdown. Nostalgia-driven groups continue to archive and recreate these experiences as of 2025, including the Teletext group and an associated server for enthusiasts to share captures, discuss , and collaborate on emulations, underscoring Teletext's influence on early online socialization.

Legacy and Evolution

Transition to Digital Teletext

As analog television broadcasting declined in the early , Teletext services transitioned to digital standards to maintain compatibility with emerging digital TV platforms like . The European Telecommunications Standards Institute (ETSI) defined the Enhanced Teletext specification in EN 300 706 (initially published in 1997 and updated in 2003), which provided the framework for transmitting Teletext data in digital bitstreams, including support for subtitles and information pages. This standard was integrated into the (DVB) framework through specification A041, which details how ITU-R System B Teletext—equivalent to EBU Teletext—is conveyed within DVB transport streams using Packetized Elementary Stream (PES) packets. Additionally, DVB standards enabled IP data transmission over broadcast channels, allowing Teletext-like services to evolve into more flexible data delivery without relying solely on vertical blanking interval (VBI) lines. In the , the adapted its service for digital transmission starting with the launch of digital terrestrial TV in 1998, providing enhanced access to news, weather, and program guides via set-top boxes and integrated digital TVs. continued in this digital format through the national switchover period, broadcasting until its final shutdown on 23 2012, aligning with the completion of the UK's analog-to-digital transition. In the , broadcasters followed the NorDig migration plan agreed in 2002, shifting from VBI-based Teletext to Multimedia Home Platform (MHP)-enabled digital services; for instance, Sweden's SVT launched MHP applications in 2003 to support interactive Teletext features across platforms in cable, satellite, and terrestrial networks. This digital shift offered significant advantages over analog Teletext, primarily through higher data rates—analog systems were limited to effective capacities of around 200-300 kbps due to VBI constraints, while streams could allocate up to 150 kbps or more for Teletext within overall transport rates of 2-12 Mbps, enabling faster page loading and richer content. Integration with Electronic Program Guides (EPGs) was facilitated by ETSI EN 300 707 (1995), which embedded EPG data within Teletext structures, allowing seamless navigation between program schedules and additional information services in digital receivers. By 2025, digital Teletext has been phased out or significantly reduced in several European countries amid the rise of internet-based alternatives, such as the UK's full cessation in and Norway's shutdown of Tekst TV on 20 2025. However, it persists in others for subtitles and basic information, including Germany's ARD and services, which continue broadcasting digital Teletext without announced end dates. In , Japan's ISDB-T standard incorporates enhanced Teletext services for data broadcasting, remaining active as part of ongoing digital terrestrial TV operations since the 2011 analog switch-off.

Internet and Web-Based Successors

As the broadcast era of Teletext waned, its core principles of simple, text-based information delivery found new life through internet-based emulators and viewers that recreate the original experience on modern devices. Web-based tools emerged in the 2010s to render archived or live Teletext pages using HTML and CSS, preserving the blocky, monochrome aesthetic and page-navigation mechanics without requiring analog TV hardware. For instance, NMS Ceefax provides an up-to-date recreation of the BBC's historic Ceefax service, allowing users to browse simulated news, weather, and TV listings in a faithful Teletext-style interface directly in web browsers. Similarly, TextTV.io, launched in 2015, initially targeted SVT's Swedish Teletext service but expanded to include content from Dutch, Italian, Norwegian, and Finnish broadcasters, rendering pages with a monospace font to mimic the original 40-column format for news and schedules. Complementing these web emulators, dedicated archive sites have digitized and made accessible thousands of historical Teletext pages extracted from VHS recordings and other analog sources. The Teletext Archaeologist project, active since the early , maintains an open repository of over 1,200 recovered teletext services spanning to 2016, enabling interactive browsing of snapshots from broadcasters like the , ITV, and international equivalents via a searchable web interface. This effort highlights Teletext's enduring appeal as a low-data medium, with pages loadable on minimal bandwidth connections, echoing its original design for efficient broadcast transmission. Mobile applications have further extended Teletext's reach by emulating page-flip navigation and content delivery on smartphones and tablets. Apps such as TxtVideo Teletext (available since the mid-2010s) function as optimized browsers for public Teletext web feeds from Italian and other European channels, simulating the sequential page cycling and color-coded blocks of traditional decoders. The Swiss TELETEXT app, updated as recently as 2025, delivers real-time , , and business updates from SRF in a hybrid interface that blends classic Teletext emulation with touch-based controls, ensuring compatibility with low-end devices. Likewise, the Croatian HRT Teletekst app (launched in 2017) combines TV-style page navigation with modern search, providing access to over 100 pages of content optimized for mobile data constraints. In the 2020s, Teletext concepts have inspired artistic revivals that leverage its constrained format for creative expression, often broadcast on residual analog services or simulated online. The International Teletext Art Festival, organized through the Museum of Teletext Art (MUTA), features ongoing solo exhibitions on YLE's Finnish teletext pages (e.g., page 805), with 2020s installments including ARD TEXT in 2020 and Tehcnoroubble in 2024, where artists like Raquel Meyers use Teletext's limited palette to explore themes of obsolescence and . These projects, viewable via web emulators, demonstrate Teletext's influence on and low-res aesthetics, fostering a niche of creators who value its deliberate simplicity over high-fidelity visuals. By 2025, Teletext persists in niche retro computing circles, where enthusiasts resurrect it on vintage hardware like the or via setups to stream custom pages over the web, blending with modern tinkering. Its text-heavy, structure continues to inform practices suited to low-bandwidth environments, as seen in performance-optimized sites that prioritize fast-loading, device-agnostic content similar to Teletext's original efficiency for resource-limited access. Teletext, as a one-way broadcast system embedded in television signals, shared conceptual similarities with several contemporaneous text and graphics delivery technologies, though it differed in interactivity and access models. Videotex systems, in contrast, were typically bidirectional and relied on public switched telephone networks (PSTN) for , enabling user queries and transactions. A prominent example was France's , launched nationwide in 1982 by the state-owned postal and telecommunications service (PTT), which provided access to directories, banking, reservations, and messaging services through dedicated terminals or adapted televisions connected via phone lines. At its peak in the mid-1990s, served approximately 25 million users across more than 26,000 services, representing nearly half of France's population and generating significant revenue through premium-rate calls. Unlike Teletext's passive reception, 's interactive nature fostered early online communities and , but required subscription fees and infrastructure investment, limiting its model to paid access. Other broadcast-based systems paralleled Teletext's one-way delivery but focused on narrower applications. In the United States, closed captioning for the deaf and hard-of-hearing emerged in the 1970s, utilizing line 21 of the vertical blanking interval (VBI) in the television signal to transmit hidden text synchronized with audio. The (FCC) reserved this line in 1976 following successful tests by station WETA in 1973, with the first national broadcasts occurring in 1980 on shows like ABC's The Wonderful World of Disney. This system, developed by the National Captioning Institute, emphasized accessibility over general information provision, reaching millions through standard televisions equipped with decoders by the late , but lacked Teletext's navigational pages or graphics capabilities. Japan developed its own advanced broadcast teletext under the Japanese Teletext Specification (JTES), standardized as CCIR in the late 1970s and widely deployed in the and . JTES supported full-color , double-height characters, and higher resolution than European standards, integrated into both analog and early Hi-Vision (analog HDTV) broadcasts starting in 1989. Services like NHK's character broadcasting provided news, weather, and , with adoption growing alongside Hi-Vision's rollout, which included data services in its encoding. By the , JTES enabled mosaic-style images and multilingual support, influencing regional systems in , though its impact remained more technical than the widespread cultural penetration of European Teletext. Hybrid systems blended broadcast and telephone elements, offering partial interactivity. The United Kingdom's , introduced by the (later British Telecom) in 1979, functioned as a dial-up service delivering text and simple graphics via modified TVs or dedicated adapters over phone lines. It targeted business and consumer information like news and directories but struggled with low adoption due to high costs and limited content, peaking at around 100,000 users by the mid-1980s before evolving into online predecessors. Similarly, Israel's early teletext service, launched in 1986 by the , incorporated phone-based enhancements for limited interactivity, such as quiz responses, distinguishing it from pure broadcast models. Key distinctions between Teletext and these systems lay in access and economics: Teletext's free, over-the-air model required no phone calls or subscriptions, enabling broad, instantaneous reach via existing TVs with decoders, which boosted its popularity in with millions of daily users by the 1980s. In comparison, like and imposed per-minute charges, achieving deeper engagement but narrower global scale outside , where 's 25 million users contrasted with Teletext's estimated 100 million European households by 1990. Broadcast analogs like prioritized niche utility, while JTES exemplified regional innovation in graphics without Teletext's emphasis on magazine-style . These parallels highlighted Teletext's role as an accessible precursor to digital services, influencing but not directly evolving into interactive paradigms.

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