![]() ![]() ![]() Since the Post Office owned the telephones, this was considered to be an excellent way to drive more customers to use the phones. Unlike Teledata, a one-way service carried in the existing TV signal, Viewdata was a two-way system using telephones. 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. However, as the low cost was essential to the project's long-term success, this obstacle had to be overcome. In reality, there was no scope to make an economic teletext system with 1971 technology. A major objective for Adams during the concept development stage was to make teletext affordable to the home user. 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. In 1971, CAL engineer John Adams created a design and proposal for UK broadcasters. The original idea was the brainchild of Philips (CAL) Laboratories in 1970. 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. In the early 1970s work was in progress in Britain to develop such a system. 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. It requires limited bandwidth at a rate of perhaps a few words per second. Transmitting and displaying subtitles was relatively easy. 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. 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. However, many European television stations continue to provide teletext services and even make teletext content available via web and dedicated apps. 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. Other standards were developed around the world, notably NABTS (CCIR Teletext System C) in the United States, Antiope (CCIR Teletext System A) in France and JTES (CCIR Teletext System D) in Japan, but these were never as popular as their European counterpart and most closed by the early 1990s. This standard saw widespread use across Europe starting in the 1980s, with almost all televisions sets including a decoder. Teletext formed the basis for the World System Teletext standard (CCIR Teletext System B), an extended version of the original system. Meanwhile, the UK's General Post Office introduced the Prestel system using the same display standards but run over telephone lines using bi-directional modems rather than the send-only system used with televisions. Similar systems were subsequently introduced by other television broadcasters in the UK and mainland Europe in the following years. Also, paged subtitle (or closed captioning) information was transmitted using the same system. It offered a range of text-based information, typically including news, weather and TV schedules. Public teletext information services were introduced by major broadcasters in the UK, starting with the BBC's Ceefax service in 1974. Teletext was created in the United Kingdom in the early 1970s by John Adams, Philips' lead designer for video display units. In broad terms, it can be considered as Videotex, a system for the delivery of information to a user in a computer-like format, typically displayed on a television or a dumb terminal, but that designation is usually reserved for systems that provide bi-directional communication, such as Prestel or Minitel. The user can display chosen pages using their remote control. ![]() The teletext decoder in the television buffers this information as a series of "pages", each given a number. Teletext sends data in the broadcast signal, hidden in the invisible vertical blanking interval area at the top and bottom of the screen. Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipped television sets. A British Ceefax football index page from October 2009, showing the three-digit page numbers for a variety of football news stories ![]()
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