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TELETEXT OUTSIDE THE UK

Following the development of the UK teletext system work began in the late 70s to adapt the principles of data broadcasting to display information for use in other countries. 

In the USA, two forms of "UK-style" teletext were proposed; one worked as the UK system does but broadcasting one line of 32 characters per TV line, the other used a 40 character per line system (as the UK system does), broadcasting part of a line per TV line. (The differences were necessary because of the differences in the format of the TV signals in the two countries.)

 

A conventional mosaic graphics page (like Ceefax)

The French system used a different presentation method. Their system, called Antiope, sent information in packets and allowed for dynamically redefinable character sets, so a much wider range of information could be displayed.

 

A sample of Antiope

In 1981 a joint specification based upon Antiope was proposed by France, Canada and the CBS network in the USA. This eventually became NAPLPS (North American Presentation Level Protocol). This described the page layout and graphics and worked more like the "digital teletext" services being introduced nowadays than the UK teletext system. A subset of the protocol was described for teletext use but it is unclear whether this method was actually used for broadcast services. The system was trialled for Viewdata ("teletext over the 'phone") in competition with "UK-style" (like UK teletext) Viewdata.

 

A sample DRCS page

Work also took place in Japan on a graphical presentation of teletext, there to cater for the requirement to display Japanese language characters. Their system was called Captain and trials started in 1979 (though it is unclear whether it ever reached broadcast stage or was only ever used for Viewdata).

 

A sample Captain page

The illustrations here are taken from the book The Architecture of Videotex Systems by Jan Gecsei, University of Montreal (published by Prentice-Hall Inc, ISBN 0-13-044776-5) and show differences in the way information is displayed by the various systems

 

A sample Telidon page (Geometic coding)

Teletext Gallery: Around the World | Teletext on the Internet

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