Teletext and to pad out the fixed packet. The vertical caption position is determined by the packet address. 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 used lines (41 7-bit 'bytes' per line, on each of 25 frames per second). A teletext page comprises
Teletext systems of standard teletext in 1991. The CBC ran a teletext service, IRIS, accessible only in Calgary, Toronto and Montreal. It ran from 1983 until about 1986, and used the Canadian-developed Telidon system, which was developed in 1980. Like Antiope, Telidon allowed significantly higher graphic resolution than standard teletext. Adoption in the United States was hampered due to a lack of a single teletext standard and consumer resistance to the high initial price of teletext decoders. Throughout the period of analogue broadcasting, teletext or other similar technologies in the US were practically non-existent, with the only technologies resembling such existing in