I think you might have it in the US but not for residential customers.
No, frequency-modulating the 50/60 Hz is not technically feasible, that would mean speeding up/slowing down lots of synchronous motors quickly. Instead, a higher-frequency low-voltage generator is connected in series or in parallel (via a capacitor) to the secondary of a grid transformer, overlaying some 3V sine wave at 216⅔ Hz (or other frequency thereabouts) on top of the 230V 50Hz mains. This does not propagate beyond 50 km or so (and higher frequencies (red on map) even worse) so multiple transmitters are required for coverage. The country’s grid is divided into districts and each gets their own RCS signal, and signal traps (low pass or band stop fiters) are used to divide them.
I think you might have it in the US but not for residential customers.
No, frequency-modulating the 50/60 Hz is not technically feasible, that would mean speeding up/slowing down lots of synchronous motors quickly. Instead, a higher-frequency low-voltage generator is connected in series or in parallel (via a capacitor) to the secondary of a grid transformer, overlaying some 3V sine wave at 216⅔ Hz (or other frequency thereabouts) on top of the 230V 50Hz mains. This does not propagate beyond 50 km or so (and higher frequencies (red on map) even worse) so multiple transmitters are required for coverage. The country’s grid is divided into districts and each gets their own RCS signal, and signal traps (low pass or band stop fiters) are used to divide them.