Also, some things, such as the main index page, are broadcast more frequently than other pages (so people just turning on teletext don't see a blank screen for ages).Also in the teletext signal is the TSDP (where the accurate clock information is taken from), and subtitles (if provided). Well, let's assume these extra things take a quarter of a page worth of data each, that's one less page every second - so it does factor into the time taken, even if only a little bit.On the other hand, though, the clock signal (an extended packet, not the clock at the upper-right of the teletext page) is useless for any television (although some TVs display the channel identification that is also present).
Given a suitable broadcaster, it will even change to and from "daylight savings" time for you.
Teletext is broadcast in the "Vertical Blanking Interval" (VBI) lines of the television signal.
Instead of being 'request-driven' like the internet, teletext just sends each frame to you in sequence, over and over.
If you had fast enough hardware (and I mean really fast), you could probably grab a complete snapshot of all the pages broadcast in about twenty or thirty seconds. Instead, we typically fetch a page, then fetch another page, and so on.
Sys Media has provided RTÉ with an innovative IP-based teletext page editing system that allows bookmakers across the country to provide rapid updates to vital onscreen betting information.
The system is now fully operational following earlier trials.
Teletext is free, simple and up-to-date (well, mostly).
It consists of a variety of numbered frames that you can access via a suitably equipped television or computer.
RTÉ Publishing, a division of Ireland’s national broadcaster, RTÉ, uses Sys Media’s PLASMA teletext production and management system to power the Aertel teletext services on both RTÉ 1 and RTÉ 2 as well as the internet.
To give bookmakers instant access to update their content on these Aertel services, RTÉ selected Sys Media’s Win SPRITE page editing technology.
On the other hand, though, teletext is completely free.