An interesting idea
Would be to figure out a way to send a GPS equivalent signal on a mostly unused wifi channel (eg in the UK that could be Channel 14) also containing emergency broadcast signals locally.
An app installed on most phones could then use the information and display messages as needed.
This isn't actually as stupid as it sounds, as it would only ever be used in an emergency so should stay clear otherwise. As invariably power would go out there would be less interference than usual considerably extending range.
I could actually test this idea, the simplest method would be a TDMS based signal derived from fixed-but-secret-location atomic clocks so a "ping" would not overlap with other units.
Also included, radiation monitoring and locations of rescue centres etc based on the known reference points. If the system detects a GNSS outage or major anomaly it turns on automagically.
Biting the hand that feeds IT
