[gm3dmo]

There is already a time signal in the electrical grid:

https://www.meinbergglobal.com/english/info/time-synchroniza...

> Why don't they just always use this Tech. I don't understand.

The bit's that get your oven to work don't need the time. Adding the bits for this is a cost and a thing that can fail because it can't receive the radio signal that equals a Dead on Arrival for your oven and a service call at least. When it's on a watch it's likely near your wrist which is likely near a window which likely means it can get the radio signal to sync.

[toomuchtodo]

Your citation is about using GPS as reference for electrical grid operations/control purposes (very common if your use case can rely on GPS versus local high precision time sources such as a cesium clock). If you were referring to using electrical grid frequency for time keeping, that is a suboptimal solution due to frequency stability nuance.

https://www.dhs.gov/sites/default/files/publications/GPS-PNT...

https://phys.org/news/2011-06-power-grid-disrupt-clocks.html

https://medium.com/@bramus/grid-time-or-why-are-clocks-in-eu...

https://www.entsoe.eu/news/2018/03/06/press-release-continui...

https://www.nist.gov/publications/time-and-frequency-electri... ("Due to the efforts of Henry Warren, inventor of the Telechron electric clock, electric power companies have been a source of time and frequency reference for the public for over a hundred years. However, advances in technology and changes in the electric power industry have generated a movement within the industry to end the time-reference service.")

[Aloha]

As mentioned by a parallel commenter, your link doesnt say what you think it does.

That said, the most power line synchronization is useful for is clocking not time, and to be very honest, its only a consistent clocking source in some places (who perform adjustment to ensure a long term value of 50/60 Hz), which means it can be used to provide a clock source to keep a device in sync, which already knows the time, but cant be used for cold start of a device.

[_trampeltier]

Usually yes, the frequency in the electric grid is pretty stable but ..

.. it's not really precise 50Hz, just +/- 50Hz.

.. there are more than just proof of concepts, you can tell from a video, when it was made from the backround noise from the main grid.

https://www.umiacs.umd.edu/publications/seeing-enf-natural-t...

.. a few years ago, was the European electric network several minutes to late, because not every country did pay for the electric power.

https://www.nationalgeographic.com/science/article/european-...