I can’t think of anything that quite fits that off-the-cuff, at least not in the US. A quick search doesn’t turn anything up. I can think of some related things:
The AC signal is used as a clock in a number of devices. This isn’t a “clock” in the common-language sense of the word, but in the electrical engineering sense – it provides a reliable frequency over the long run. Some (common-language) clocks and timers have used this to keep them running at a steady pace, but it’s not really a time signal, wouldn’t help restore an on-device clock setting after power loss.
X10 is a low-speed networking protocol that runs over local power circuits for home automation. I’m sure that at some point, someone has made some product that permits setting a clock with it. The limitation is that your signal doesn’t span across household circuits, which I suspect one would want for a “whole house time signal”.
There have been powerline-based ISPs, where the power company shovels data over the line using high-frequency modulation. In theory, you could use one of various Internet time protocols over that. I think that that was kind of a dead end, technology-wise — there’s just not that much data that you can push over an unshielded, non-twisted-pair, metal power line.
I would not be surprised if there’s some data protocol that power companies use to talk to smart meters that includes pushing a time signal out specifically for them – they do push and pull data over that – though I don’t think that that’s accessible to other devices.
That being said, could be some company out there that did that locally. Not technically impossible.
I can’t think of anything that quite fits that off-the-cuff, at least not in the US. A quick search doesn’t turn anything up. I can think of some related things:
The AC signal is used as a clock in a number of devices. This isn’t a “clock” in the common-language sense of the word, but in the electrical engineering sense – it provides a reliable frequency over the long run. Some (common-language) clocks and timers have used this to keep them running at a steady pace, but it’s not really a time signal, wouldn’t help restore an on-device clock setting after power loss.
X10 is a low-speed networking protocol that runs over local power circuits for home automation. I’m sure that at some point, someone has made some product that permits setting a clock with it. The limitation is that your signal doesn’t span across household circuits, which I suspect one would want for a “whole house time signal”.
There have been powerline-based ISPs, where the power company shovels data over the line using high-frequency modulation. In theory, you could use one of various Internet time protocols over that. I think that that was kind of a dead end, technology-wise — there’s just not that much data that you can push over an unshielded, non-twisted-pair, metal power line.
I would not be surprised if there’s some data protocol that power companies use to talk to smart meters that includes pushing a time signal out specifically for them – they do push and pull data over that – though I don’t think that that’s accessible to other devices.
That being said, could be some company out there that did that locally. Not technically impossible.