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
Electra (teletext) operation. A few other services were offered by some large-market TV stations in the US throughout the 1980s, such as "Metrotext" from KTTV in Los Angeles and "KeyFax" from WFLD in Chicago. Electra also carried another teletext service on its higher-numbered pages, a service called "Tempo". Tempo mainly carried sports (and other miscellaneous) information on its pages. At the time of Electra's closing in 1993, it was the only existing teletext service in the USA. 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