I'm curious about the technicalities of the “radio alert transmission system” (RATS), which indeed sounds like a cold war-era system, but I couldn't find much a

I'm curious about the technicalities of the “radio alert transmission system” (RATS), which indeed sounds like a cold war-era system, but I couldn't find much around. Any idea? You have to admit that a radio announcement that starts with “This is the BBC from London” is a creepy reminder of old times.