We’ve come full circle.

https://news.ycombinator.com/item?id=46952384

https://github.com/tanvach/clocksync

https://github.com/kangtastic/timestation

https://github.com/hzeller/txtempus

WVB: A Tiny WWVB Station - https://news.ycombinator.com/item?id=13258631 - December 2016 (49 comments)

https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

I’ve thought it’d be fun to find the chip used in those clocks, and integrate it into an offline microcontroller driven clock, but haven’t found the will to do so yet. I haven’t even looked for prior art, which I’m certain exists.

Or for Western Europe there is DCF77 https://en.wikipedia.org/wiki/DCF77