Nevertheless, Level 2.5 became a standard for receivers, especially for higher-end sets. Well-known television manufacturers such as Grundig, Loewe, Metz, Sony, Philips and B&O presented devices compatible with this new service.Īlthough some broadcasters based their service on the new Teletext Level 2.5, the service was not widely adopted by broadcasters. With further development, including the introduction of error correction, it also became possible to transmit audio and video files.ĪRD and ZDF presented Teletext Level 2.5 at the IFA Berlin in 1995. One example was a method used for the automatic control of video recorders using VCR 5, introduced in 1985. In the coming years, many applications were developed in which data was transmitted parallel to Teletext. The vertical blanking interval was not only used for Teletext. A simple concept which has not changed over the years.
Simply press the Teletext key and enter three numbers for the desired page – and that’s it. The navigation in Teletext is straightforward. However, with a connected memory, it is possible to save the pages and thus recall them more quickly. So you must wait until the selected page is picked up to be displayed. The pages are transmitted in a carousel, one after the other. Each of these primary pages can contain up to 99 sub-pages. There is a maximum of 800 individually accessible primary pages, numbering from 100 to 899. During this time no image is displayed, and the incoming signal could be used to transmit additional data.Įach page of Teletext consists of 24 lines each with 40 characters. The time it took the beam to jump back from the last line to the first line was called the vertical blanking interval. When consumer electronic companies still used cathode ray tubes inside analogue television sets, the picture was built up line by line from top to bottom by an electron beam.
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