As a more recent example of a similar concept, TiVo would distribute guide data to their DVRs using encoded video broadcast during overnight Paid Programming time slots. The practice ran from about 1999 to 2016. Around 2016, TiVo discontinued support for guide data updates for their first-generation Series1 DVRs. I couldn't find much information about these broadcasts online, though someone did post a clip of one from 2003 [1], there are a few copies of more recent introduction and conclusion animations [2], and there is some information about them on Wikipedia [3]. It could be a fun project to try to decode it.
You still get guide data if you hook up an Ethernet jack and let it download data online. You need a USB Ethernet adapter, but even a cheap one is fine.
I remember there was even a slot (I think it was PCI electrically?) on the gen 1 TiVos you could buy a real ethernet card for and then cut a slot in the case to run the cable out.
That was a long time ago. I can't imagine there are that many Gen 1 TiVos still in use. I think they were SD only. Certainly don't support ATSC, so you would have to have a compatible converter box if you have it hooked up to an antenna.
Yeah, I had one of the original Ethernet-converted TiVos, made by my roommate at the time who hand-soldered the debug port to ISA adapter from a blank PCB and a bag of parts. We rooted it, put an NE-2000 card in it, and then didn't need our home phone line anymore. (Also tossed an 80GB WD drive in it to replace the pathetic 20GB it came with.)
Network-connected download of the guide data stopped working a number of years ago. I was still using mine connected to basic cable, which still had standard-def channels. (And yes, the ATSC to NTSC converter boxes could be persuaded to work.) Eventually, something like an HDHomeRun setup is a lot easier... but nothing will ever replace the "feel" of the TiVo remote. Particularly the 15-second skip button!
I worked with the guy that created that. It wasn’t at TiVO but a gaming company. He said it was also how they updated the TiVO firmware. It’s been years but I recall him telling the story about how they updated the TiVO using channels that were encoded a specific way.
[1]: https://www.youtube.com/watch?v=VfUgT2YoPzI
[2]: https://www.youtube.com/watch?v=Hnu97CHDrYI
[3]: https://en.wikipedia.org/wiki/Infomercial#TiVo