World System Teletext
Encyclopedia
World System Teletext is the name of a standard for encoding and displaying teletext
information, which is used as the standard for teletext throughout Europe today.
It originally stems from the UK standard developed by the BBC
and the UK Independent Broadcasting Authority
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 under international standard CCIR 653 (now ITU-R
BT.653) as one of four recognised standards for teletext worldwide, and may now most commonly be referred to as CCIR Teletext System B.
Almost all television sets sold in Europe since the early 80s have built-in WST-standard teletext decoders as a feature.
WST is used for all teletext services in Europe & Scandinavia, including Ceefax
from the BBC
and services from Teletext
on ITV
in the United Kingdom
, ZDFtext from ZDF
and ARDText from ARD in Germany
, and Tekst-TV from NRK in Norway
, among many other teletext services offered by other television networks throughout the European continent.
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 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. In the event only Level 2.5 was implemented, in some countries from the late 1990s, allowing some viewers with appropriate equipment to see the pages enhanced with a more flexible use of a wider range of colours, smoother graphics, and better international language support.
in the 1980s, for the Electra
service, which was carried on SuperStation WTBS (now TBS Superstation). It was also used for other teletext services on other television stations and networks in the USA as well.
Zenith in the US also included built-in WST teletext decoders in their higher-end models of TV sets, such as their Digital System 3 line throughout the 1980s. Also, Dick Smith Electronics
offered through their American distributors a WST teletext decoder in the form of a set-top box, which was sold as a kit.
This was all in competition to another teletext standard developed exclusively in North America, NABTS
(North American Broadcast Teletext Standard). It was developed in Canada by Norpak
, and was used by CBS
for their ExtraVision
service and for a very short time by NBC
in the mid 1980s. However, NABTS never became as successful as WST in the American continent, since NABTS was a more advanced technology, which required a much more complicated and expensive decoder (even though it had improved graphics capability over WST).
Teletext
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...
information, which is used as the standard for teletext throughout Europe today.
It originally stems from the UK standard developed by the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
and the UK Independent Broadcasting Authority
Independent Broadcasting Authority
The Independent Broadcasting Authority was the regulatory body in the United Kingdom for commercial television - and commercial/independent radio broadcasts...
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
NTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...
525-line system as necessary, this was then promoted internationally as "World System Teletext". It was accepted by CCIR
ITU-R
The ITU Radiocommunication Sector is one of the three sectors of the International Telecommunication Union and is responsible for radio communication....
in 1986 under international standard CCIR 653 (now ITU-R
ITU-R
The ITU Radiocommunication Sector is one of the three sectors of the International Telecommunication Union and is responsible for radio communication....
BT.653) as one of four recognised standards for teletext worldwide, and may now most commonly be referred to as CCIR Teletext System B.
Almost all television sets sold in Europe since the early 80s have built-in WST-standard teletext decoders as a feature.
WST is used for all teletext services in Europe & Scandinavia, including Ceefax
Ceefax
Ceefax is the BBC's teletext information service transmitted via the analogue signal, started in 1974 and will run until April 2012 for Pages from Ceefax, while the actual interactive service will run until 24 October 2012, in-line with the digital switchover.-History:During the late 60s, engineer...
from the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
and services from Teletext
Teletext Ltd.
Teletext Ltd was the provider of teletext and digital interactive services for ITV, Channel 4 and Five in the United Kingdom.-Origins:Teletext Ltd started providing teletext services for ITV and Channel 4 on 1 January 1993, replacing the previous Oracle service which had lost the franchise...
on ITV
ITV
ITV is the major commercial public service TV network in the United Kingdom. Launched in 1955 under the auspices of the Independent Television Authority to provide competition to the BBC, it is also the oldest commercial network in the UK...
in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, ZDFtext from ZDF
ZDF
Zweites Deutsches Fernsehen , ZDF, is a public-service German television broadcaster based in Mainz . It is run as an independent non-profit institution, which was founded by the German federal states . The ZDF is financed by television licence fees called GEZ and advertising revenues...
and ARDText from ARD in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, and Tekst-TV from NRK in Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, among many other teletext services offered by other television networks throughout the European continent.
In the early 1980s a number of higher extension levels were envisaged for the specification, based on ideas then being promoted for worldwide videotex
Videotex
Videotex was one of the earliest implementations of an "end-user information system". From the late 1970s to mid-1980s, it was used to deliver information to a user in computer-like format, typically to be displayed on a television.In a strict definition, videotex refers to systems that provide...
standards (telephone dial-up services offering a similar mix of text and graphics). 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. In the event only Level 2.5 was implemented, in some countries from the late 1990s, allowing some viewers with appropriate equipment to see the pages enhanced with a more flexible use of a wider range of colours, smoother graphics, and better international language support.
WST in the United States
WST also saw some use in the United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in the 1980s, for the Electra
Electra (teletext)
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...
service, which was carried on SuperStation WTBS (now TBS Superstation). It was also used for other teletext services on other television stations and networks in the USA as well.
Zenith in the US also included built-in WST teletext decoders in their higher-end models of TV sets, such as their Digital System 3 line throughout the 1980s. Also, Dick Smith Electronics
Dick Smith Electronics
Dick Smith is an international electronics retailer, founded in 1968 by Richard "Dick" Smith. Today, it is a subsidiary of Woolworths Limited, incorporating Tandy, and the remaining Dick Smith Powerhouse Stores...
offered through their American distributors a WST teletext decoder in the form of a set-top box, which was sold as a kit.
This was all in competition to another teletext standard developed exclusively in North America, NABTS
NABTS
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 of an analog video signal...
(North American Broadcast Teletext Standard). It was developed in Canada by Norpak
Norpak
Norpak Corporation was a company headquartered in Kanata, Ontario, Canada, that specialized in the development of systems for television-based data transmission...
, and was used by CBS
CBS
CBS Broadcasting Inc. is a major US commercial broadcasting television network, which started as a radio network. The name is derived from the initials of the network's former name, Columbia Broadcasting System. The network is sometimes referred to as the "Eye Network" in reference to the shape of...
for their ExtraVision
ExtraVision
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 VBI of the video from local affiliate stations of the CBS network...
service and for a very short time by NBC
NBC
The National Broadcasting Company is an American commercial broadcasting television network and former radio network headquartered in the GE Building in New York City's Rockefeller Center with additional major offices near Los Angeles and in Chicago...
in the mid 1980s. However, NABTS never became as successful as WST in the American continent, since NABTS was a more advanced technology, which required a much more complicated and expensive decoder (even though it had improved graphics capability over WST).
Further reading
- World System Teletext Technical Specification, UK Department of Trade and Industry, 1985. Also retitled as World System Teletext and Data Broadcasting System Technical Specification, various revisions until 1989.
- CCIRITU-RThe ITU Radiocommunication Sector is one of the three sectors of the International Telecommunication Union and is responsible for radio communication....
653 (now ITU-RITU-RThe ITU Radiocommunication Sector is one of the three sectors of the International Telecommunication Union and is responsible for radio communication....
BT.653) set of four standards for teletext systems worldwide. Adopted 1986. Revisions 2 and 3 were published in 1993 and 1998. WST was formalised by this standard as CCIR Teletext System B. - Enhanced Teletext specification ETS 300 706 (ETSI, 1997); Version 1.2.1, April 2003. Current European standard for CCIR Teletext System B.