Once upon a time in Europe, television remote controls had a magic teletext button. Years before the internet stole into homes, pressing that button brought up teletext digital information services with hundreds of constantly updated pages. Living in Ireland in the 1980s and ’90s, my family accessed the national teletext service— Aertel —multiple times a day for weather and news bulletins, as well as things like TV program guides and updates on airport flight arrivals. It was an elegant system: fast, low bandwidth, unaffected by user load, and delivering readable text even on analog television screens. So when I recently saw it was the 40th anniversary of Aertel ’s test transmissions, it reactivated a thought that had been rolling around in my head for years. Could I make a ham-radio version of teletext? What is Teletext? First developed in the United Kingdom and rolled out to the public by the BBC under the name Ceefax , teletext exploited a quirk of analog television signals.…