I'm planning on building my own Teletext service at some point as part of a wider analogue TV project. It's a cool form for things like the news because you have to be very concise for it to work in such a constrained format; it's the opposite of today where long-form content that doesn't really say anything is dirt cheap to emit at scale. Some of the British services had rudimentary games too like Bamboozle, a quiz game which relied on hexadecimal pages the remote couldn't enter manually.
One thing I'd also like to reinstate is NICAM digital stereo which British analogue TV used to have, most modulators I've come across only generate a mono FM subcarrier in PAL mode so looks like I'm going to be building my own modulator.
That brings back fond memories of my first employer in the early 90s.
They used to rent a single scan line (VBI) of the TV broadcast to use as a data transmission method encoded the same way Teletext was. IIRC you could fit 45 bytes in a single scan line, with 50 per second that gives you a nationwide data broadcast capability of something like 18 kbit/s. We had a 19,200 bits/second leased line to send the data.
That scan line was really really expensive I seem to remember! If your TV wasn't quite adjusted properly you could see the data scan lines at the top of the screen as flickering white dots and lines which was fun.
The data got sent to financial institutions for real time stock feeds and nationwide networks of shops.
I never worked on the code for that part of the business though - I worked on the replacement system which ran via satellite with much more bandwidth at much lower cost.
I love learning about pre-internet ways of transferring data on the back of other things. Another cool example is that the UK is only shutting down its longwave AM radio service this month (as opposed to decades ago) because the carrier is phase-modulated with data telling older electric meters to switch over. For years this was the only reason such an antiquated radio system stayed alive.
Imagine a meshtastic network of devices across a city or country, broadcasting a set of rotating teletext pages with no ability to censor it. That would be something.
> with no ability to censor it
Except, of course, policemen knocking on your door. Wouldn't be necessary anyways, most people would not even try broadcasting on the mere threat of arrest.
There are actually multiple implementation of networking over ham radio (though not using teletext).
Some of the limitations are that ham radio requires getting a license (it's easy, but it's a little bit of work and turns some people off), the user base is tiny (it's a niche inside a niche), it requires technical knowledge and specialized hardware, and legally it can't be encrypted or used for commercial purposes. That's okay if your plan is to broadcast messages without censorship, but not so great if you want to check email or browse https sites.
Please consider framing your project in your mind as a hobby.
It’s valuable to the degree that you enjoy it. Learning and other external values don’t have to apply here.
Just the fun of doing it can be enough.
I think you had 999 pages but each page could have 9999 sub pages.
The pages were send one by one so if you typed 200 you would have to wait for page 200 to cycle by. If it had 100 sub pages you would have to wait 100 times as long. I believe more important pages could be send more often or similarly the cycle would skip less important pages. Decent TV's would just store pages and sub pages until the next cycle.
I asked crappy local TV stations what a page would cost but they didn't have anything under 1500 guilders per month (comparable to $1500 today) which was an absurd amount of money for 1kb of hosting.
No wonder that, besides news, subtitles and the tv guide, the thing was entirely filled with lottery phone lines, astrology lines, sex lines and similar trash.
Viewing the fee as being for a volume of storage doesn't seem the right perspective. It's $1500 to lease some %age of spectrum for some period. If true Teletext on an analogue signal and broadcast vs cable, then $1500 for 0.05% of the total non-media spectrum doesn't feel like a terrible deal.
$1500 today is probably in the region of 10s of GB, sure, but that's almost a commodity volume by comparison in terms of supply.
This Teletext emulator displays a few projects recreating various services: https://zxnet.co.uk/teletext/viewer/.
I'm planning on building my own Teletext service at some point as part of a wider analogue TV project. It's a cool form for things like the news because you have to be very concise for it to work in such a constrained format; it's the opposite of today where long-form content that doesn't really say anything is dirt cheap to emit at scale. Some of the British services had rudimentary games too like Bamboozle, a quiz game which relied on hexadecimal pages the remote couldn't enter manually.
One thing I'd also like to reinstate is NICAM digital stereo which British analogue TV used to have, most modulators I've come across only generate a mono FM subcarrier in PAL mode so looks like I'm going to be building my own modulator.
That brings back fond memories of my first employer in the early 90s.
They used to rent a single scan line (VBI) of the TV broadcast to use as a data transmission method encoded the same way Teletext was. IIRC you could fit 45 bytes in a single scan line, with 50 per second that gives you a nationwide data broadcast capability of something like 18 kbit/s. We had a 19,200 bits/second leased line to send the data.
That scan line was really really expensive I seem to remember! If your TV wasn't quite adjusted properly you could see the data scan lines at the top of the screen as flickering white dots and lines which was fun.
The data got sent to financial institutions for real time stock feeds and nationwide networks of shops.
I never worked on the code for that part of the business though - I worked on the replacement system which ran via satellite with much more bandwidth at much lower cost.
Eventually the internet killed that too :-)
I love learning about pre-internet ways of transferring data on the back of other things. Another cool example is that the UK is only shutting down its longwave AM radio service this month (as opposed to decades ago) because the carrier is phase-modulated with data telling older electric meters to switch over. For years this was the only reason such an antiquated radio system stayed alive.
> I love learning about pre-internet ways of transferring data on the back of other things
See Minitel from France and Telidon from Canada as other examples of data systems riding on analogue TV and/or POTS telephone systems.
Imagine a meshtastic network of devices across a city or country, broadcasting a set of rotating teletext pages with no ability to censor it. That would be something.
The same author dabbled in a similar project, so maybe there's a Teletext over ham radio tie-in possible?
https://spectrum.ieee.org/run-a-meshtastic-bbs
> with no ability to censor it Except, of course, policemen knocking on your door. Wouldn't be necessary anyways, most people would not even try broadcasting on the mere threat of arrest.
Seems like we have all the key technologies to edit anonymously and distribute info P2P-style with no known central control mechanism.
There are actually multiple implementation of networking over ham radio (though not using teletext).
Some of the limitations are that ham radio requires getting a license (it's easy, but it's a little bit of work and turns some people off), the user base is tiny (it's a niche inside a niche), it requires technical knowledge and specialized hardware, and legally it can't be encrypted or used for commercial purposes. That's okay if your plan is to broadcast messages without censorship, but not so great if you want to check email or browse https sites.
https://spectrum.ieee.org/build-a-longdistance-data-network-...
https://www.reddit.com/r/amateurradio/comments/5bj5w0/intern...
Please consider framing your project in your mind as a hobby. It’s valuable to the degree that you enjoy it. Learning and other external values don’t have to apply here. Just the fun of doing it can be enough.
I'm familiar with the author's past work on ieee.org and have a sense that he likes to write to/for both hobbyist and professional camps:
https://spectrum.ieee.org/u/stephen-cass
Ham radio as a whole is a great hobby to sink your random RF projects into already.. its a hobby within a hobby, no matter what path you may take ;)
I think you had 999 pages but each page could have 9999 sub pages.
The pages were send one by one so if you typed 200 you would have to wait for page 200 to cycle by. If it had 100 sub pages you would have to wait 100 times as long. I believe more important pages could be send more often or similarly the cycle would skip less important pages. Decent TV's would just store pages and sub pages until the next cycle.
I asked crappy local TV stations what a page would cost but they didn't have anything under 1500 guilders per month (comparable to $1500 today) which was an absurd amount of money for 1kb of hosting.
No wonder that, besides news, subtitles and the tv guide, the thing was entirely filled with lottery phone lines, astrology lines, sex lines and similar trash.
Viewing the fee as being for a volume of storage doesn't seem the right perspective. It's $1500 to lease some %age of spectrum for some period. If true Teletext on an analogue signal and broadcast vs cable, then $1500 for 0.05% of the total non-media spectrum doesn't feel like a terrible deal.
$1500 today is probably in the region of 10s of GB, sure, but that's almost a commodity volume by comparison in terms of supply.